Laboratory work No. 1
Subject: “Preparation and description of micropreparations of cells of various organisms.”
Goal of the work: consolidate the ability to prepare microspecimens and examine them under a microscope, find structural features of cells of various organisms, and master the terminology of the topic.
Equipment: skin of bulb scales, epithelial cells from the human oral cavity, culture of Bacillus subtilis, glass of water, microscope, teaspoon, cover glass and slide glass, blue ink, iodine, micropreparations of cells of a multicellular animal organism, notebook, pen, pencil, ruler,
Progress:
Work 1.
1. Consider in the figure the sequence of preparing the onion skin preparation.
2. Prepare the slide by wiping it thoroughly with gauze.
3. Use a pipette to place 1-2 drops of water onto the slide.
4. Using a dissecting needle, carefully remove a small piece of transparent skin from the inner surface of the onion scale. Place a piece of peel in a drop of water and straighten it with the tip of a needle.
5. Cover the peel with a cover slip as shown in the picture.
6. Examine the prepared preparation at low magnification. Note which parts of the cell you see.
7. Stain the preparation with iodine solution. To do this, place a drop of iodine solution on a glass slide. Use filter paper on the other side to pull off excess solution.
8. Examine the colored preparation. What changes have occurred?
9. Examine the preparation at high magnification. Find the chloroplasts in the leaf cells, the dark stripe surrounding the cell, the membrane; underneath is a golden substance - the cytoplasm (it can occupy the entire cell or be located near the walls). The nucleus is clearly visible in the cytoplasm. Find the vacuole with cell sap (it differs from the cytoplasm in color).
10. Sketch 2-3 cells of onion skin. Label the membrane, cytoplasm, nucleus, vacuole with cell sap.
In the cytoplasm of a plant cell there are numerous small bodies - plastids. At high magnification they are clearly visible. In the cells of different organs the number of plastids is different.
In plants, plastids can be of different colors: green, yellow or orange and colorless. In the skin cells of onion scales, for example, plastids are colorless.
Work 2.
1. Prepare a microscopic specimen of Bacillus subtilis bacteria.
2. Examine the preparations under a microscope.
3. Consider ready-made micropreparations of cells of a multicellular animal organism.
4. Compare what you see with the image of the object in the picture.
Job 3
Consider ready-made micropreparations of multicellular animal cells
Compare what you see with the image of the object in the picture.
3. Label the cell organelles shown in Fig. 4
^
Laboratory work No. 2
Subject: “Observation of the phenomenon of plasmolysis and deplasmolysis”
Target: verify the existence of the phenomenon of plasmolysis and deplasmolysis in living plant cells and the speed of physiological processes.
Equipment: microscopes, slides and cover glasses, glass rods, glasses of water, filter paper, table salt solution, onions.
Progress
Remove the bottom skin of the onion scales (4mm 2);
Prepare a microslide, examine and sketch 4-5 cells of what you see;
On one side of the cover glass, apply a few drops of table salt solution, and on the other side, draw off the water with a strip of filter paper;
Examine the microslide for a few seconds. Pay attention to the changes that have occurred to cell membranes and the time during which these changes occurred. Sketch the changed object.
Apply a few drops of distilled water to the edge of the coverslip and pull it off the other side with filter paper, rinsing off the plasmalysis solution.
Examine the slide under a microscope for several minutes. Note the changes in the position of the cell membranes and the time during which these changes occurred.
Compare what you see with the image of the object in Figure 1.
Sketch the object you are studying.
Draw a conclusion in accordance with the purpose of the work, noting the rate of plasmolysis and deplasmolysis. Explain the difference in speed of these two processes.
1. Where did the water move (into or out of the cells) when the tissue was placed in a salt solution?
2. How can we explain this direction of water movement?
3. Where did the water move when the fabric was placed in water? What explains this?
4. What do you think could happen in the cells if they were left in a salt solution for a long time?
5. Can salt solution be used to kill weeds?
6. Define the terms - plasmolysis, deplasmolysis, osmosis, turgor.
7. Explain why apples become less juicy when cooked in jam?
Figure 1. Plasmolysis and deplasmolysis
Laboratory work No. 3
Subject: “Comparison of the structure of plant and animal cells, fungi, bacteria.”
Target: learn to find structural features of cells of different organisms and compare them with each other; master the terminology of the topic.
Equipment: microscopes, slides and cover glasses, glasses with water, glass rods, leaves of the Elodea plant, yeast, culture of Bacillus subtilis, micropreparations of cells of multicellular animals.
Work 1.
1. Prepare a preparation of Elodea leaf cells. To do this, separate the leaf from the stem, place it in a drop of water on a glass slide and cover with a coverslip.
2. Examine the preparation under a microscope. Find chloroplasts in the cells.
3. Draw the structure of an Elodea leaf cell. Write captions for your drawing. 4.Look at Figure 1. Draw a conclusion about the shape and size of the cells different plant organs
Rice. 1. Color, shape and size of cells of different plant organs
Work 2.
1.Remove some mucus from the inside of your cheek with a teaspoon. 2. Place the mucus on a slide and tint with blue ink diluted in water. Cover the preparation with a coverslip. 3. Examine the preparation under a microscope.
Job 3
Consider a ready-made micropreparation of cells of a multicellular animal organism.
 |  |  |
| bacterial cell | plant cell | animal cell |
Compare these cells with each other.
Enter the comparison results in Table 1
Answer the questions:
What are the similarities and differences between cells?
What are the reasons for the similarities and differences between cells of different organisms?
Practical work
Subject : “Drawing up the simplest crossing schemes.”
Target: learn to write out the types of gametes formed by organisms with given genotypes; briefly write down the conditions of genetic tasks; solve situational problems in genetics; use genetic terminology skills.
Equipment: textbook, notebook, task conditions, pen.
Progress:
Exercise 1
Write down all types of gametes formed by organisms having the following genotypes: AAbb, Aa, MmPP, PPKk, AabbCc, AabbCcPP, AaBbCc.
When writing out gametes, it is necessary to remember that in an organism homozygous for one (AA) or several (AAbbcc) genes, all gametes are identical in these genes, since they carry the same allele.
In the case of heterozygosity for one gene (Aa), the organism forms two types of gametes carrying different alleles. A diheterozygous organism (AaBb) produces four types of gametes. In general, an organism produces more types of gametes the more genes it is heterozygous for. The total number of gamete types is 2 to the power of n, where n is the number of genes in the heterozygous state. When writing out gametes, it is necessary to be guided by the law of “purity” of gametes, according to which each gamete carries one of each pair of allelic genes.
Task 2
Learn to briefly write down the conditions of a genetic situational problem and its solution.
When writing briefly the conditions of a genetic problem, a dominant character is denoted by a capital letter (A), and a recessive character by a lowercase letter (a) indicating the corresponding variant of the trait. The genotype of an organism that has a dominant trait, without additional indications of its homo- or heterozygosity in the task conditions, is designated A?, where the question reflects the need to establish the genotype in the course of solving the problem. The genotype of an organism with recessive traits is always homozygous for the recessive allele - aa. Sex-linked traits are designated in the case of X-linked inheritance as Xª or XA
^ An example of a brief recording of the condition and solution to the problem
Task. In humans, the brown eye color variant is dominant over the blue eye color variant. A blue-eyed woman marries a heterozygous brown-eyed man. What eye color can children have?
Brief description of the condition Brief description of the solution
A - brown eye color Parents - R aa x Aa
A – blue eye color of the gamete - G a A, a
Parents: aa x Aa offspring - F Aa aa
Offspring? brown color blue color
Task 3
Briefly write down the condition of the genetic situational problem and its solution.
Problem: In humans, myopia dominates normal vision. Myopic parents gave birth to a child with normal vision. What is the genotype of the parents? What other children could there be from this marriage?
Practical work
Subject : “Solving genetic problems.”
Target: learn to solve genetic problems; explain the influence of external factors on the manifestation of a trait; use genetic terminology skills.
Equipment: textbook, notebook, task conditions, pen.
Progress:
1. Remember the basic laws of inheritance of traits.
2. Collective analysis of problems on monohybrid and dihybrid crossing.
3. Independent solution of problems on monohybrid and dihybrid crossing, describing in detail the process of solution and formulating a complete answer.
4. Collective discussion of problem solving between students and teacher.
5. Draw a conclusion.
Monohybrid crossing problems
Problem No. 1. In cattle, the gene that determines the black coat color is dominant over the gene that determines the red color. What kind of offspring can be expected from crossing a homozygous black bull and a red cow?
Let's look at the solution to this problem. First, let's introduce some notation. In genetics, alphabetic symbols are used for genes: dominant genes are designated in capital letters, recessive genes are designated in lowercase letters. The gene for black color is dominant, so we will designate it as A. The gene for red coat color is recessive - a. Therefore, the genotype of a black homozygous bull will be AA. What is the genotype of a red cow? It has a recessive trait that can manifest itself phenotypically only in a homozygous state (organism). Thus, her genotype is aa. If a cow's genotype had at least one dominant gene A, then its coat color would not be red. Now that the genotypes of the parent individuals have been determined, it is necessary to draw up a theoretical crossing scheme
A black bull produces one type of gamete according to the gene under study - all germ cells will contain only gene A. For ease of calculation, we write down only the types of gametes, and not all the germ cells of a given animal. A homozygous cow also has one type of gamete - a. When such gametes merge with each other, one, the only possible genotype is formed - Aa, i.e. all offspring will be uniform and will carry the trait of a parent with a dominant phenotype - a black bull..
Thus, the following answer can be written: when crossing a homozygous black bull and a red cow, only black heterozygous calves should be expected in the offspring
The following problems should be solved independently, describing in detail the solution and formulating a complete answer.
Problem No. 2. What kind of offspring can be expected from crossing a cow and a bull that are heterozygous for coat color?
Problem No. 3. In guinea pigs, curly hair is determined by a dominant gene, and smooth hair is determined by a recessive gene.
1. Crossing two frizzy pigs with each other produced 39 individuals with frizzy hair and 11 smooth-haired animals. How many of the individuals with a dominant phenotype should be homozygous for this trait?
2. A guinea pig with curly hair, when crossed with an individual with smooth hair, produced 28 curly and 26 smooth-haired offspring. Determine the genotypes of parents and offspring.
^ Problems on di- and polyhybrid crossing
Task No. 7. Write down the gametes of organisms with the following genotypes: AABB; aabb; ААББ; aaBB; AaBB; Aabb; AaBb; AABBSS; AALCC; AaBCC; AaBCss.
Let's look at one example. When solving such problems, it is necessary to be guided by the law of gamete purity: a gamete is genetically pure, since it contains only one gene from each allelic pair. Let's take, for example, an individual with the genotype AaBbCc. From the first pair of genes - pair A - either gene A or gene a enters each germ cell during the process of meiosis. The same gamete receives gene B or b from a pair of genes B located on another chromosome. The third pair also supplies each germ cell with the dominant gene C or its recessive allele - c. Thus, a gamete can contain either all dominant genes - ABC, or recessive genes - abc, as well as their combinations: ABC, AbC, Abe, aBC, aBc, and bC.
In order not to be mistaken in the number of gamete varieties produced by an organism with the genotype under study, you can use the formula N = 2n, where N is the number of gamete types, and n is the number of heterozygous gene pairs. It is easy to verify the correctness of this formula using examples: heterozygote Aa has one heterozygous pair; therefore, N = 21 = 2. It forms two types of gametes: A and a. Diheterozygote AaBb contains two heterozygous pairs: N = 22 = 4, four types of gametes are formed: AB, Ab, aB, ab. Triheterozygote AaBCCc, in accordance with this, should form 8 types of germ cells N = 23 = 8), they have already been written out above.
Problem No. 8. In cattle, the polled gene dominates over the horned gene, and the gene for black coat color dominates over the gene for red color. Both pairs of genes are located on different pairs of chromosomes.
1. What kind of calves will turn out to be if you cross heterozygous for both pairs?
Signs of a bull and a cow?
2. What kind of offspring should be expected from crossing a black polled bull, heterozygous for both pairs of traits, with a red horned cow?
^ Additional tasks for laboratory work
Problem No. 1. A litter of 225 minks was obtained at the fur farm. Of these, 167 animals have brown fur and 58 minks are bluish-gray in color. Determine the genotypes of the original forms if it is known that the gene for brown color is dominant over the gene that determines the bluish-gray coat color.
Problem No. 2. In humans, the gene for brown eyes dominates over the gene causing blue eyes. A blue-eyed man, one of whose parents had brown eyes, married a brown-eyed woman whose father had brown eyes and whose mother had blue eyes. What kind of offspring can be expected from this marriage?
Task No. 3. Albinism is inherited in humans as a recessive trait. In a family where one of the spouses is an albino and the other has pigmented hair, there are two children. One child is albino, the other has dyed hair. What is the likelihood of having your next albino child?
Problem No. 4. In dogs, black coat color dominates over coffee, and short hair dominates over long hair. Both pairs of genes are located on different chromosomes.
1. What percentage of black shorthair puppies can be expected from crossing two individuals heterozygous for both traits?
2. A hunter has purchased a black dog with short hair and wants to be sure that it does not carry the genes for a long, coffee-colored coat. Which phenotype and genotype partner should be selected for crossing in order to check the genotype of the purchased dog?
Problem No. 5. In humans, the gene for brown eyes dominates over the gene that determines the development of blue eyes, and the gene that determines the ability to better use the right hand prevails over the gene that determines the development of left-handedness. Both pairs of genes are located on different chromosomes. What kind of children can they be if their parents are heterozygous?
Task No. 6. In humans, the recessive gene a determines congenital deaf-muteness. A hereditarily deaf-mute man married a woman with normal hearing. Is it possible to determine the genotype of a child's mother?
Task No. 7. From the yellow pea seed a plant was obtained that produced 215 seeds, of which 165 were yellow and 50 were green. What are the genotypes of all forms?
Task No. 8. Father and mother feel the bitter taste of phenylthiourea. Two out of four children do not feel the taste of this drug. Assuming that differences in sensitivity to phenylthiourea are monogenic, determine whether insensitivity to phenylthiourea is dominant or recessive.
1. What is the unit of structure of living beings? What is it called and who gave it that name?
The cell is the structural unit of living things.
cell theory was developed by German scientists T. Schwann and M. Schleiden.
2. How long ago did people learn that the bodies of living beings consist of cells? Explain why this was not known before?
In 1665, examining the thinnest section of a cork under an improved three-lens microscope at 40x magnification, Robert Hooke discovered tiny cells, similar to the same cells in honey, and gave them the name “cells.” Also in 1665, Robert Hooke first reported the existence of cells.
3. Are there cells that can be seen without a microscope? If yes, please provide examples.
Plant cells with large vacuoles: onions, oranges, pamella. You can hold these large cells in your hands. There are also organisms belonging to the kingdom of fungi with giant multinucleate cells forming multinucleate schizonds.
4. Look at the picture on p. 30 textbook. Name the main parts of a living cell.
Parts of the cell: cytoplasm (semi-liquid substance); nucleus (storage and transmission of hereditary information); nuclear envelope - separates the nucleus from the cytoplasm; ribosomes - protein synthesis; mitochondria (energy is produced; cell center - cell division.
5. What features of cells indicate that they are alive?
Cells breathe, grow, eat, divide.
6. The human body originates from a single cell, formed as a result of the fusion of two germ cells. An adult body consists of approximately 100 trillion cells. Where do so many cells come from?
Many cells appear due to the fact that the cells of the body are characterized by constant division through mitosis. From one cell two daughter cells are formed. At this rate, a large number of cells appear in the human body.
7. In the picture, look at the cells of different parts of the plant and the human body. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
Each group of cells in the body performs a specific function (nutrition, respiration, reproduction, etc.), because There are many processes in the body necessary for normal functioning; one cell could not cope with them, therefore the cells in the body are distributed according to the functions they perform.
Human cells: multinucleated cells - will be cells of striated muscle tissue; colorless cells with an amoeba-like shape - leukocytes, whose function is photosynthesis; red anucleate cells - erythrocytes (carriers of oxygen and carbon dioxide).
Plant cells: small, colorless, tightly adjacent cells - these are skin cells; green bean-shaped cells - guard cells of the stomata; green cells are cells that carry out photosynthesis.
8.* Explain why the egg is much larger than most other cells.
This one cell contains the basis for the development of absolutely all other cells, the whole organism, as well as the initial reserve for growth and nutrition. An example of this is not only the cells inside mammals, whose children develop and grow in the womb. But for example, the eggs of birds and amphibians are a real egg. Only developing outside the mother's body. That is, this one cell contains all the substances from which the rest will later be formed.
Question 1. What is the unit of structure of living beings? What is it called and who gave it that name?
The unit of structure, functioning and development of living beings is the cell. This name was given to it by the English naturalist and encyclopedist Robert Hooke (1635 - 1703).
Question 2. How long ago did people learn that the bodies of living beings consist of cells? Explain why this was not known before.
In 1665, examining the thinnest section of a cork under an improved three-lens microscope at 40x magnification, Robert Hooke discovered tiny cells, similar to the same cells in honey, and gave them the name “cells.” Also in 1665, Robert Hooke first reported the existence of cells.
Question 3. Are there cells that can be seen without a microscope? If yes, please provide examples.
Plant cells with large vacuoles: onions, oranges, pomelo. You can hold these large cells in your hands. There are also organisms belonging to the kingdom of fungi with giant multinucleate cells forming multinucleate schizonds.
Question 4. Look at the picture on page 108 of the textbook. Name the main parts of a living cell.
Each cell has three main parts: the outer membrane that covers the cell, the cytoplasm - a semi-liquid mass that makes up the main contents of the cell, and the nucleus - a small dense body located in the cytoplasm.
Question 5. What features of cells indicate that they are alive?
The cells are alive. They breathe, eat, grow and divide. One cell turns into two. Then from each new one, when it grows, two more. Thanks to this, the entire body grows and develops.
Question 6. The human body originates from a single cell, formed as a result of the fusion of two germ cells. An adult body consists of approximately 100 trillion cells. Where do so many cells come from?
Many cells appear due to the fact that the cells of the body are characterized by constant division through mitosis. From one cell two daughter cells are formed. At this rate, a large number of cells appear in the human body.
Question 7. Look at the picture of the cells of various parts of the animal. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
There are often many types of cells in the body. They differ from each other in shape and size. For example, the cells that form muscles, bones, and the nervous system in the human body look completely different. There are also special cells - reproductive cells. They are different for men and women. The female reproductive cell is called the egg, and the male cells are called sperm. These cells give rise to a new organism; in other words, children are born thanks to them. For this to happen, the egg and sperm must unite. Their fusion is called fertilization. The fertilized egg divides many times, and an embryo develops from it.
Question 8: Explain why eggs are much larger than most other cells.
This one cell contains the basis for the development of absolutely all other cells, the whole organism, as well as the initial reserve for growth and nutrition. An example of this is not only the cells inside mammals, whose children develop and grow in the womb. But for example, the eggs of birds and amphibians are a real egg. Only developing outside the mother's body. That is, this one cell contains all the substances from which the rest will later be formed.
Current page: 2 (book has 8 pages total) [available reading passage: 2 pages]
5. Living cells
This happened more than 300 years ago. The English scientist Robert Hooke examined under a microscope a thin section of a bottle cap made from the bark of a cork oak tree. What Hooke saw was a great discovery. He discovered that the cork consisted of many small cavities, chambers, which he called cells. It was soon discovered that other parts of plants also consist of cells. Moreover, it was discovered that the bodies of animals and humans are built from cells.
Hooke's microscope. Section of a cork under a microscope
If we could shrink ourselves a million times, amazing possibilities would open up for us. We could go inside cells and explore them the way travelers explore mysterious jungles, caves, or the depths of the sea. If we were tireless and visited the inside of a variety of organisms, we would be able to find out the following.
No matter how diverse the living creatures that inhabit our planet are, they all have a cellular structure. The bodies of plants, animals, and humans are built from cells, like houses made of bricks. Therefore, cells are often called the “building blocks” of the body. But this is a very, very rough comparison.
Firstly, the cells are complex, not like bricks fashioned from clay. Each cell has three main parts: outer membrane who dresses the cage, cytoplasm– a semi-liquid mass that constitutes the main contents of the cell, and core- a small dense body located in the cytoplasm.
Secondly, our “building blocks” are alive. They breathe, eat, grow... and divide. One cell turns into two. Then from each new one, when it grows, two more. Thanks to this, the entire body grows and develops.
This is what a modern microscope looks like
And finally, thirdly, in the body there are most often many types of cells. They differ from each other in shape and size. For example, the cells that form muscles, bones, and the nervous system in the human body look completely different. There are also special cells - sexual. They are different for men and women. The female reproductive cell is called egg, and male cells – spermatozoa. These cells give rise to a new organism; in other words, children are born thanks to them. For this to happen, the egg and sperm must unite. Their merger is called fertilization. The fertilized egg divides many times, and an embryo develops from it. Human development in the mother's body lasts 9 months. When a child is born, it is difficult to believe that life was given to him by only two small cells - the mother's egg and the father's sperm.
There are approximately 200 types of cells in the human body. And their total number is about 100 trillion. This number is written like this: 100,000,000,000,000.
Big world of small cells*
We already know that the body of any plant, animal, or human has organs. The cell also has “organs”. They are located in the cytoplasm and are called organoids, i.e. “similar to organs.” You can see some of them in the picture. Mitochondria are responsible for cell respiration, lysosomes are responsible for digestion. And the network of channels resembles blood vessels - through them different substances pass from one part of the cell to another.
Almost all cells are very small. You can't see them without a microscope. And you have all seen the chicken egg more than once: this is the yolk of the egg. Huge cage! It is even greater in an ostrich egg: after all, about 30 chicken eggs could fit in it.
The eggs of fish and frogs - eggs - are much smaller than those of birds. But they are also much larger than most other cells.
The eggs are so large because they contain a large supply of nutrients necessary for the development of the embryo.
Many plant cells contain special green organelles - chloroplasts(from the Greek “chloros” - green). They give the plant its green color. Chloroplasts are very important for plants: it is in them that nutrients are formed in the light.
Questions and tasks
1. What is the unit of structure of living things? What is it called and who gave it that name?
2. How long ago did people know that the bodies of living beings consist of cells? Explain why this was not known before.
3. Are there cells that can be seen without a microscope? If yes, please provide examples.
4. Look at the drawing. Name the main parts of a living cell.
5. What features of cells indicate that they are alive?
6. The human body originates from a single cell, formed as a result of the fusion of two germ cells. An adult body consists of approximately 100 trillion cells. Where do so many cells come from?
7. Consider the cells of different parts of the plant and the human body in the picture. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
8.* Explain why eggs are much larger than most other cells.
Living things have a cellular structure. The main parts of a cell are the outer membrane, cytoplasm and nucleus. Living cells breathe, eat, grow, and divide. They are varied in shape and size. Among them are germ cells that give rise to a new organism.
6. Chemical composition of the cell
You already know that all living organisms are similar in structure: they consist of cells. But it turns out that their chemical composition is also similar - the cells of all organisms consist of the same elements. Currently, scientists have been able to detect more than 80 chemical elements out of 111 known in the cell.
Elements found in a living cell are also widespread in inanimate nature - the atmosphere, water, and the earth's crust. There are no elements that are found only in living organisms.
Most elements are found in the cell in the form of chemical compounds - substances. There are inorganic and organic substances.
The most common inorganic substance in a living organism is water, its content averages up to 80% of body weight. Even tooth enamel contains 10% water, and bones contain up to 20%. This is explained by the role that water plays in the cell. First of all, it determines the physical properties of the cell, its volume, elasticity. Numerous chemical reactions take place in an aqueous environment, since water is a good solvent. And water itself participates in many chemical reactions.
Clam shells are made of calcium salts
Hemoglobin is found in erythrocytes - red blood cells
Starch accumulates in potato tubers
Water helps remove unnecessary and harmful substances from the body that are formed as a result of metabolism, and promotes the movement of oxygen, carbon dioxide and nutrients throughout the body.
Part of living organisms and mineral salts, however, in small quantities: they constitute up to 1% of the cell mass. The most common are sodium and potassium salts; they ensure the performance of such an important body function as irritability. Calcium salts give strength to bone tissue and the shells of numerous mollusks.
Organic substances are found only in living organisms. These are proteins, fats, carbohydrates, nucleic acids.
Squirrels- These are the main substances of the cell. If all the water is removed from a cell, then 50% of its dry mass will be proteins. These are very complex connections. The protein hemoglobin carries oxygen and is what gives blood its red color. Not a single movement associated with muscle contraction is carried out without contractile proteins. Proteins are also involved in protecting the body from infections, blood clotting and many other processes.
They also play an important role in the body carbohydrates. These are well-known glucose, sucrose (beet sugar that we eat every day), fiber, and starch. The main function of carbohydrates is energy. By “burning” glucose, the body receives the energy necessary for the processes taking place in it. Living organisms can store carbohydrates in the form of starch (plants) and glycogen (animals and fungi). In potato tubers, starch makes up up to 80% of the dry weight. Animals have a particularly high amount of carbohydrates in liver and muscle cells - up to 5%.
Carbohydrates also perform other functions, such as support and protection. Fiber is part of wood; chitin forms the exoskeleton of insects and crustaceans.
Fats perform a number of functions in the body. They provide the body with up to 30% of the energy it needs. In some animals, fats accumulate in large quantities and protect the body from heat loss.
Fats are also of great importance as an internal water reserve. As a result of the breakdown of fats in cells, up to 1.1 kg of water is formed from 1 kg of fat. This is very important for animals that hibernate in winter - gophers, marmots: thanks to their fat reserves, they can not drink for up to two months. When crossing the desert, camels go without drinking for up to two weeks: they extract the water necessary for the body from their humps, which are receptacles for fat.
Subcutaneous fat protects the seal's body from hypothermia
Nucleic acids(from the Latin “nucleus” - core) are responsible for the storage and transmission of hereditary characteristics from parents to offspring. They are part of chromosomes - special structures located in the cell nucleus.
Chromosomes transmit hereditary traits from parents to children
The distribution of substances and individual chemical elements in nature is heterogeneous.
Some organisms actively accumulate elements, for example, brown algae - iodine, buttercups - lithium, duckweed - radium, mollusks - copper.
The body of a jellyfish consists of 95% water, human brain cells - 85%, blood - 80%. In mammals, water loss exceeding 10% of body weight leads to death.
Hair, nails, claws, fur, feathers, and hooves consist almost entirely of protein. Snake venom is also protein.
In whales, the thickness of the subcutaneous fat layer reaches 1 m.
Brown algae fucus
Diagram of the occurrence of chemical elements on Earth
Solidified lava
Mineral crystals
Rock faults
Stalactite formations in a cave
Questions and tasks
1. List the elements that make up the basis of living organisms.
2. What substances are classified as inorganic? organic? Using the drawing, make pie charts of the content in the cell (in%) of inorganic and organic substances.
3. What is the function of water in a living organism?
4. Describe the importance of mineral salts in the body.
5. What is the role of proteins in the body?
6. Name the carbohydrates you know. Which of them are found in plant and which in animal organisms? Describe the significance of these organic substances.
7. Describe the role of fats in the body.
8. What organic substances of the cell ensure the storage and transmission of hereditary information? Where are they located in the cage?
9. Look at the diagrams. How does the chemical composition of living and nonliving bodies differ? Are there elements that are found only in living organisms?
10. What facts indicate the unity of origin of all living organisms?
Study of the chemical composition of seeds.
Refer to the electronic application
Study the material and complete the assigned tasks.
The most common elements in living organisms are oxygen, carbon, nitrogen, and hydrogen. Living organisms include organic substances (proteins, fats, carbohydrates, nucleic acids) and inorganic substances (water, mineral salts).
7. Substances and phenomena in the surrounding world*
Substances
The world that surrounds a person is very diverse. You have studied the structure of the Solar System and know that it is made up of the Sun, planets, their satellites, asteroids, comets, and meteorites. They are all called bodies. While studying the structure of the Earth, you also become familiar with bodies - these are pieces of rocks and minerals. Plants, animals, humans are also bodies.
Everything that surrounds us - bodies of living and inanimate nature, products - consists of substances. Iron, glass, salt, water, polyethylene are substances. There are a lot of them. Currently, more than 7 million different substances are known, and every year people synthesize new, previously unknown ones. Scientists in many countries are working to create environmentally friendly automobile fuel, highly effective mineral fertilizers, medicines for influenza, AIDS and many other diseases.
In nature, substances exist in three states: solid, liquid and gaseous. Substances can change from one state to another.
In most cases, substances are found in the form mixtures. Sometimes this is clearly visible even to the naked eye. For example, looking at a piece of granite, you can see that it consists of a mixture of substances: quartz, mica and feldspar, but in homogeneous-looking milk, only under a microscope can you distinguish droplets of fat and proteins floating in the liquid (water).
Components of granite
Substances without impurities are called clean. Such substances do not exist in nature. Their production is one of the important tasks of the chemical industry. Pure substances are used in electronics, the nuclear industry, and in the production of medicines.
Impurities can dramatically change the properties of substances. A small addition of salt or sugar will change the taste of water, a drop of ink will change its color. This feature was noticed a very long time ago. Ancient metallurgists obtained alloys (mixtures of metals) - bronze, brass and others, which differed from the original metal, copper, in being more durable and resistant to water and air. When producing steel, a slight addition of the metal chromium makes it stainless, and the addition of tungsten gives it the ability to withstand very high temperatures.
In the mixture, each substance retains its properties. Knowing these properties, mixtures can be divided into their component parts.
Mixture separation
There are substances simple And complex. In order to answer the question of how they differ, you need to know the structural features of the substance. For centuries, scientists have been trying to find out how it works.
Models of molecules of simple and complex substances
It is now known that all substances consist of tiny particles: molecules, atoms or ions. They are so small that it is impossible to see them with the naked eye. Molecules are particles made up of atoms. Atoms of the same type are called elements. One molecule can have two, three, or even hundreds or thousands of atoms. Ions are modified atoms. In the future, you will learn about the structure of these particles in more detail.
By studying the structure of atoms, scientists have established that atoms differ from each other, that is, in nature there are different types of atoms: one type is oxygen atoms, the other is carbon atoms, etc. Modern science knows 111 types of atoms (elements). Combining with each other in various combinations, they form the variety of substances that exist in nature.
Now we can answer the question posed. If substances contain atoms of the same type, then such substances are called simple. These are metals that are well known to you (iron, copper, gold, silver) and non-metals (sulfur, phosphorus, graphite and many others).
Heating a mixture of iron and sulfur. Preparation of the complex substance iron sulfide. Iron + sulfur = iron sulfide
Liquid water
water vapor
Substances consisting of particles formed by atoms of different types are called complex. For example, water, carbon dioxide.
As a result of the reaction, a new complex substance can be obtained, for example iron sulfide. It does not contain simple substances - sulfur and iron. They are included in its composition as atoms of certain types (sulfur atoms and iron atoms).
Variety of natural phenomena
The world around us is constantly changing: water evaporates, snow melts, rocks are destroyed, wood burns, iron rusts, thunder rumbles, lightning flashes. Such changes are called phenomena. What do they have in common and how are they different? Let's do a little research.
You see that when heated, the shape of the body (a piece of ice) changed, but the composition of the substance (water) remained the same.
When a copper plate was heated, a new substance was formed - copper oxide.
The experiments carried out show that in some cases the formation of new substances occurs, in others – not. Based on this feature, physical and chemical phenomena are distinguished.
When water is heated, no new substances are formed
When a copper plate is heated, copper atoms interact with oxygen atoms, and a new substance is formed
TO physical include thermal, mechanical, light, sound, electrical and magnetic phenomena. We encounter them all the time in everyday life.
Iron rail joints
Phenomena associated with heating and cooling of bodies are called thermal.
When heated, the length and volume of bodies increase, and when cooled, they decrease. This phenomenon must be taken into account in construction and industrial production. When laying railway and tram tracks, small gaps are left at the joints of the rails, so that when the rail is heated and lengthened, the track is not destroyed. When building bridges, one end of the bridge is usually installed on special rollers. Thanks to this, the bridge does not collapse during thermal expansion or contraction.
Installation of a bridge on special rollers
Change in water condition
When the temperature changes, a substance can move from one state to another, which is clearly seen in the example of a change in the state of water.
An example of mechanical phenomena is a change in the shape of a body, such as the compression and expansion of a spring.
The movement of living organisms, celestial bodies, transport, rolling stones and snow from mountains, lifting and lowering loads, rotation of wheels - all movements of bodies in space are also mechanical phenomena.
Light phenomena are associated with the characteristics of the light beam. For example, the straightness of its propagation explains the formation of shadows.
Solar eclipse
The ability of light to reflect off the bodies on which it falls gives us the ability to see them.
Light phenomena in nature, such as rainbows, are amazingly beautiful. It is formed as a result of the decomposition of light in raindrops.
These are just some examples of physical phenomena. The main feature of all these phenomena is the preservation of substances.
Now let's consider chemical phenomena. In another way, these phenomena are called chemical transformations or chemical reactions. As a result of such reactions, new substances are formed that differ from the original ones in a number of ways.
Man uses chemical reactions to produce mineral fertilizers, medicines, paints, and detergents. Scientists create new substances that do not exist in nature.
Some chemical reactions occur very slowly, and we do not notice them; they last for billions of years. For example, a hard rock, limestone, is destroyed by water and carbon dioxide and transformed into other substances. Water washes them away - this is how voids and caves are formed in the mountains.
Other reactions occur very quickly (combustion, explosion). This is how fuel burns in a car engine or gas burner. When burning, a lot of heat and light are released.
Decomposition of light through a glass prism and a drop of water
Signs of chemical reactions
When dead parts of plants rot, heat is also released, but it is dissipated in the surrounding space. We usually do not notice this heat, but we must take it into account. An incorrectly folded haystack or poor straw storage conditions lead to the development of the rotting process. This can even cause spontaneous combustion of the material.
Questions and tasks
1. In what states can substances exist in nature?
2. Give examples of solid, liquid and gaseous mixtures. Name the most common gaseous mixture on the planet.
3. What substances are called pure?
4. Why does industrial production sometimes require the use of mixtures rather than pure substances?
5. How do complex substances differ from simple ones? Give examples of simple and complex substances.
6. Why are there many times more different substances in nature than there are types of atoms?
7. How do physical phenomena differ from chemical ones?
Laboratory and practical work
Description and comparison of characteristics of various substances. Observing signs of a chemical reaction. Study of some physical phenomena.
Refer to the electronic application
Study the material and complete the assigned tasks.
All bodies are made of substances. In nature, substances can be in solid, liquid and gaseous states. There are mixtures and pure substances, simple and complex substances.
Attention! This is an introductory fragment of the book.
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The cell is
- Answer: The elementary unit of life on Earth.
40. Complete the sentences
- Answer: Of the organisms living on Earth, all except viruses have a cellular structure, and viruses have a non-cellular structure. A cell is characterized by the following vital properties: growth, nutrition, reproduction, respiration, and so on.
41. Complete the laboratory work “Looking at plant and animal cells under a microscope.”
42. The discovery of the cell is associated with the names of great scientists who studied living objects using a microscope (microscopists). Write about their scientific contributions made in the field of cell science.
1) R. Hooke (1635-1703) - first saw a cell under a microscope.
2) A. Leeuwenhoek (1632-1723) - invented the microscope, observed animal cells for the first time.
3) M. Schleiden (1804-1881) - put forward a theory about the identity of plant cells from the point of view of their development.
4) T. Schwann (1810-1882) - finally formulated the cell theory.
5) R. Virchow (1821 - 1902) - supplemented the cell theory with the fact that all living things come from cells.
6) S. G. Navashin (1857-1930) - discovered double fertilization in plants.
43. Formulate the main provisions of modern cell theory.
All living things are made up of cells.
All cells are similar in structure, chemical composition and life cycles.
Cells are capable of independent life, i.e. can eat, grow, reproduce.
44 . What do you think was the significance of the discovery of cell theory for the development of modern biology?
- Answer: The cell theory was supplemented by Virchow. His assertion that every painful change is associated with some pathological process in the cells that make up the body made a great contribution to medicine.
45. Consider the cells of the organisms shown in the figure. Determine which organisms the depicted cells belong to. Write their numbers in the appropriate lines.
Bacterial cells: 2.3.
Fungal cells: 6.11.
Plant cells: 7,1,5,4.
Animal cells: 10.8.
46. What do you think determines the shape of cells?
- Answer: From the functions they perform, from their specialization and origin.
47. Explain the importance of cytoplasm.
- Answer: It performs the function of uniting all the organelles of the cell, is the medium for all chemical and biological processes in the cell, and provides its mechanical properties.
48. What do you think are the consequences of removing or disrupting the integrity of the cell membrane?
- Answer: Violation of the integrity of the membrane, and even more so its removal, will lead to the leakage of the internal contents of the cell and its death.
49. In the figure, label the main structural components of the cell membrane.
50. Complete the sentences.
It is possible to examine the structure of the cell membrane using an electron microscope.
The basis of the cell membrane is the bilipid layer in which proteins are located.
The proteins that make up the membranes provide transmembrane transport and are also receptors and enzymes.
Nutrients enter the cell through passive and active transport.
Nutrients that enter the cell are broken down by enzymes.
51. Consider in the textbook a schematic representation of the processes of phagocytosis and pinocytosis. Remember from the course “Man and His Health” what phagocytes are and what their significance is in the human body. Indicate which of the figures shows the mechanism of action of these cells. Give more examples of cells that are characterized by these processes.
- Answer: In addition to phagocytes, some protozoa (for example, amoeba vulgaris) feed by phagocytosis.
52. Do you think reverse transport of substances across the cell membrane is possible? If yes, give examples; if no, explain why.
- Answer: Reverse transport from the cell through the membrane occurs when the cell releases unnecessary metabolic products, and the synthesis and release of hormones and enzymes also occurs.
53. Fill out the table "Structure and functions of cellular structures."
54. Give definitions of concepts.
Answer: Prokaryotes are organisms whose cells lack a formed nucleus and organelles (instead of organelles - mesosomes).
Eukaryotes are organisms whose cells have a nucleus with a nuclear membrane and all membrane-bound organelles.
55. In the figure, label the main structural components of the nucleus.
56. Continue filling out the table. Structure and functions of cellular structures.
57. Fill the table. Structure and functions of nuclear structures.
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Structure Structural features Functions Nuclear envelope Consists of 2 membranes: internal smooth and external rough. Has pores Transport of substances from the nucleus to the cell and vice versa Karyoplasma Liquid contents of the core Filling Kernel Space Chromatin Strands of DNA or chromosomes Storage and transmission of national information, division Nucleoli Dense round body suspended in nuclear juice Synthesis of RNA and proteins
58. It is known that human erythrocytes, which are a eukaryotic organism, do not contain a nucleus. How can this phenomenon be explained?
- Answer: This is explained by the laws of evolution. In the process of development of the animal world, man is at the highest level, and therefore his circulatory system is the most developed. The nucleus in human red blood cells is filled with hemoglobin. Therefore, they capture more oxygen than, for example, frogs.
59. Complete the sentences.
- Answer: Several nuclei may be contained in the cells of striated muscle fibers. The internal contents of the nucleus are called karyoplasm or nuclear juice; chromatin and nucleoli are located in it. The nucleus contains DNA molecules that ensure the storage and transmission of hereditary information about the cell. The nucleoli contained in the nuclei of cells ensure the synthesis of RNA and proteins.
60. Give definitions of concepts.
Chromosomes
- Answer: Chromatin DNA strands tightly wound into a helix onto proteins.
Chromatin
- Answer: Strands of DNA in the nucleus.
Chromatids
- Answer: Half of a duplicated chromosome.
Karyotype
- Answer: A set of chromosomes contained in cells of a particular species.
Somatic cells
- Answer: Cells that make up the organs and tissues of any multicellular organism.
Sex cells (gametes)
- Answer: Cells characteristic of male and female sexes.
Haploid set of chromosomes
- Answer: A set of chromosomes of cells of a given species of different sizes and shapes, but each chromosome is represented in the singular.
Diploid set of chromosomes
- Answer: A set of chromosomes of cells of a given species of different sizes and shapes, where there are two chromosomes of each.
Homologous chromosomes
- Answer: Paired chromosomes.
61. The table shows the number of chromosomes contained in the haploid and diploid sets of various organisms. Fill the gaps.
- Answer: Sets of chromosomes and various organisms.
62. Continue filling out the table.
-
Structure Structural features Functions Endoplasmic reticulum (ER) smooth Not covered with ribosomes Transport Endoplasmic reticulum (ER) rough Covered with ribosomes Protein synthesis in ribosomes Ribosomes Ball-shaped, composed of several parts, formed by RNA and proteins Protein synthesis Golgi complex Cavities limited from the cytoplasm by membranes and stacked The accumulation and transport of substances, in plants - also the synthesis of fiber.
63. Look at the drawing. Name the organelles shown on it and label their main parts.
64.
-
Structure Structural features Functions Lysosomes Small membrane vesicles containing enzymes inside Digestion of nutrients Mitochondria Double-membrane organelles containing cristae, ribosomes and DNA inside ATP synthesis Plastids: leucoplasts All plastids are double-membrane organelles. Colorless Starch accumulation Chloroplasts Greens Photosynthesis Chromoplasts Red, yellow, orange Coloring of fruits and flowers
65. Complete the sentences.
The cellular center performs the following functions: construction of the spindle, formation of microtubules, cilia and flagella.
The basis of the cytoskeleton is microtubules and microfilaments.
In animals and lower plants, the cell center is formed by centrioles consisting of microtubules and a centrosphere.
In higher plants the cell center
Microtubules form cell movement organelles such as cilia and flagella.
66. Continue filling out the table "Structure and functions of cellular structures."
67. The figure shows a diagram of the structure of a prokaryotic cell (cyanobacterium). Label its main parts.
68. The figure shows prokaryotic and eukaryotic cells. Determine which group each of them belongs to.
69. Fill out the table "Comparison of the cell structure of eukaryotes and prokaryotes" by placing + or - signs in the appropriate columns.
-
Organoid Contained in cells zukaryote prokaryote Core + - Cell membrane + + Cytoplasm + + Ribosomes + + Mitochondria + - Endoplasmic reticulum + - Golgi complex + - Plastids + -
70. Give definitions of concepts.
Assimilation is the entire set of reactions of biological synthesis of substances in a cell, accompanied by the expenditure of energy.
Dissimilation is a set of reactions of the breakdown of substances in a cell, accompanied by the release of energy.
Metabolism is a metabolic process that combines assimilation and dissimilation.
71. The following are the processes occurring in the cells of organisms:
1. Evaporation of water,
2. Glycolysis,
3. Breakdown of fats,
4. Protein biosynthesis,
5. Photosynthesis,
6. Breakdown of polysaccharides,
7. Fermentation
8. Breathing,
9. Biosynthesis of fats.
Enter the numbers with which they are designated, in accordance with their affiliation with assimilation and dissimilation.
Assimilation processes: 4, 5, 9.
Dissimilation processes: 1, 2, 3, 6, 7, 8.
72. Read the textbook material and fill out the table “Stages of Energy Metabolism.”
-
Stage Characteristic Description of energy conversion results Preparatory stage of energy metabolism Enzymes break down into smaller ones Little energy is released and heat is produced, but not ATP Bi-oxygen stage of energy metabolism Incomplete breakdown of glycosin is converted to alcohol Breakdown of glycolysis enzymes
2ARF (10%) - 2ATP (60%)
Oxygen stage of energy metabolism
73. Complete the sentences.
The main function of mitochondria, called the “powerhouses of the cell,” is the synthesis of ATP.
The most efficient processes of ATP synthesis occur in organisms called aerobes, in contrast to anaerobes, which are most numerous among prokaryotes.
74. What do you think the cells of which animal and human tissues should contain a large number of mitochondria? Why?
- Answer: The largest number of mitochondria are found in muscle tissue and the liver. These tissues and organs require large amounts of energy.
75. Complete the diagram "Classification of organisms by type of nutrition."
-
Organisms
76. Finish the sentence.
- Answer: The way the body feeds depends on whether it is able to independently create organic substances from inorganic substances necessary for the construction of cells and life processes, or whether it receives them from the external environment. According to the method of nutrition, green plants are autotrophs (phototrophs). The main source of energy on our planet is sunlight.
- Answer: Not possible. Some green plant cells feed heterotrophically: cambium and root cells. The cells of these parts of the plant are not capable of photosynthesis and are nourished by organic substances synthesized by the green parts of the plant.
78. Fill out the table "Autotrophic and heterotrophic organisms."
79. Fill out the table "Classification of heterotrophic organisms according to the method of obtaining organic substances."
- Answer: The process of synthesizing organic compounds from water and carbon dioxide using light energy.
- Answer: 6CO2 + 6H2O + light energy = C6H12O6 + 6O2
-
Photosynthesis occurs in green plant cells, in chloroplasts.
Oxygen released during photosynthesis is formed as a result of photolysis of water.
- Answer: Chemotrophs are organisms capable of synthesizing organic substances from inorganic ones using the energy of chemical oxidation reactions occurring in the cell.
- Answer: Chemotrophs are autotrophs. Chemosynthesis was discovered in 1887 by S. N. Vinogradsky. Chemotrophs differ from phototrophs in that they synthesize organic substances from inorganic ones using the energy of chemical oxidation reactions occurring in the cell. Phototrophs synthesize the necessary substances using the energy of sunlight.
80. Define the concept.
Photosynthesis is
81. Write down the overall equation for photosynthesis.
82. Complete the sentences.
83. Fill out the table "Comparative characteristics of the phases of photosynthesis."
84. Complete the diagram by labeling the names of the substances.
2) Oxygen
4) Hydrogen ions
5) Carbon dioxide
6) Glucose
85. Define the concept.
86. Complete the sentences.
87. Fill the table.
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