Eukaryotic cell structure. Dna and genes In which eukaryotic cells dna molecules are localized
As they are less energy-intensive, monosaccharides are degraded faster and more easily absorbed by the body than fats. Therefore, the brain cells, which constantly need a large amount of energy, use only the energy of glucose in their activity.
Answer:
Cellulose and chitin. Cellulose forms the plant cell wall. Chitin is
the basis of the outer skeleton of arthropods and the cell membrane of fungi.
Card 22 Topic: Enzymes. |
Answer: 2,3,6.
Card 23 Topic: Enzymes. |
C-1. Task. How do enzymes differ from inorganic catalysts?
Answer:
v Enzymes are substances of protein nature.
v Each accelerates the enzyme only 1chem. reaction.
v The enzyme accelerates chemical reaction faster.
Enzymes are active only under certain
conditions (t, PH, Acidity)
Card 24 Topic: Enzymes |
C-1.
What is the biochemical nature of most enzymes and why do they lose their activity when the level of radiation increases?
Answer: Most enzymes are proteins. Protein structure
the enzyme changes under the influence of radiation, denaturation occurs.
C-2. Explain according to the diagram of the picture how the formation of the "enzyme-substrate" complex occurs
Answer: Enzymes are biological catalysts that accelerate the course of biochemical reactions in the cell by hundreds of millions of times. The enzyme has a protein part (apoenzyme) and a non-protein part (coenzyme). The molecule has an active center with a configuration complementary to that of the substrate, ie, the substrate and the enzyme fit together "like a key to a lock." When the enzyme binds to the substrate, an enzyme-substrate complex is formed, then the configuration of the enzyme changes and this ensures the reaction. After the completion of the reaction, the end products of the reaction leave the enzyme and the released active center can bind with new portions of the substrate, while the amount of the enzyme does not change. Enzymes have a suffix -ase in their name, for example: lactase, polymerase.
AT 3. In what structures of eukaryotic cells are DNA molecules localized?
Card 27 Topic: Nucleic acids. DNA.
AT 6. Set correspondence.
AT 6. Establish a correspondence between nucleic acid and characteristic.
DNA replication A) unwinding the spiral of the molecule B) the effect of the enzyme DNA polymerase on the molecule C) separation of one strand from another into parts of a DNA molecule D) attachment to each DNA strand complementary nucleotides E) the formation of two DNA molecules from one Answer:A C B D E AT 8. Establish the sequence in which the DNA reduplication process takes place. A) Unwinding the spiral of the DNA molecule B) The effect of the enzyme DNA polymerase on molecules C) Separation of one strand from another at the site of the DNA molecule D) Attachment of complementary nucleotides to each DNA strand E) Formation of two DNA molecules from 1 E) Hydrogen bonds between bases are broken С-1.Problem. What is the difference in the structure of DNA and RNA nucleotides? Answer: 1) In DNA nucleotides, a monosaccharide - disoxyribose, (C5H10O4), and in ATP-ribose ( C5H10O5), 2) There are 4 types of nitrogenous bases in DNA nucleotides, (A, T, G, C), in ATP (A-_adenine). 3) There is one phosphoric acid residue in DNA nucleotides, in ATP-3.
C-2. Task. The structure of the molecule, which monomer is shown in the diagram? What is indicated by the letters A, B, C? What are the types of biopolymers? |
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Q7. Establish the sequence in which the process takes placeC-2.
P Read the text "Nucleic acids" and find sentences in the text that contain biological errors. Write down the numbers of these sentences first, and then formulate them correctly.
NUCLEIC ACIDS
(1) Nucleic acids, like proteins, are polymers. (2) Cells contain 2 types of nucleic acids - DNA and ATP. (3) Amino acids are used as monomers of nucleic acids. (4) The DNA contains 4 nitrogenous bases: adenine, lysine, thymine, cytosine. (5) DNA provides storage of hereditary information and its transfer from the mother cell to the daughter one. (6) In the middle of the 20th century, it was found that the DNA molecule consists of 2 helically twisted chains.
Answer: Biological errors: 2 3 4 sentences
Right answers:(2) Cells contain two types of nucleic acids - DNA and RNA. (3) Nucleotides are used as monomers of nucleic acids. (4) The DNA contains 4 nitrogenous bases: adenine, guanine, thymine, cytosine.
C-3. Problem. A fragment of a DNA molecule contains 1530 nucleotide residues. How many amino acids will the protein encoded by this gene contain?
Answer: Each amino acid is encoded by 3 DNA nucleotide residues. The protein will contain (1530: 3 = 510 amino acids)
C-5. A fragment of a DNA molecule contains 3693 nucleotide residues. How many amino acids will the protein encoded by this gene contain?
Answer No. 24 Each amino acid is encoded by 3 nucleotide residues of DNA. Protein will contain 3693: 3 = 1231 amino acids
C-5. Task. How many nucleotides does a gene encoding a 210 amino acid protein contain?
Answer: Genetic code - in a triplet, 1 amino acid is encoded by 3 nucleotides. Gene,
coding protein contains 210x3 = 630 nucleotide residues
C-2 .Insert the missing terms from the proposed list into the text "Protein biosynthesis". Write down the numbers of the selected answers in the text, and then write out the resulting sequence of numbers (in the text).
PROTEIN BIOSYNTHESIS
|
List of terms
1) and RNA 2) t RNA
3) broadcast 4) mutation
5) gene 6) ribosome
PROTEIN BIOSYNTHESIS
As a result of plastic metabolism, body-specific proteins are synthesized in the body. The section of DNA in which information about the structure of one protein is encoded is called the (A) gene. Protein biosynthesis begins with synthesis (B) and RNA
and the assembly itself occurs in the cytoplasm with the participation of (B) ribosome
The first stage of protein biosynthesis is called transcription, and the second (D) translation
Answer:
5163
C-2 ... Read the text and complete the table according to its sections.
PROTEIN BIOSYNTHESIS
Protein biosynthesis is a process during which hereditary information encoded in genes is realized in the form of a specific sequence of amino acids in protein molecules. It all starts with the synthesis of messenger (informational) RNA in a specific area of DNA. Messenger RNA exits through the pores of the nuclear membrane into the cytoplasm and attaches to the ribosome. The cytoplasm contains transport RNA and amino acids. Transport RNAs recognize at one end a triplet of nucleotides on messenger RNA, and at the other end they attach certain amino acids. By attaching a triplet of nucleotides encoding a given amino acid, it cleaves it into the synthesized protein chain. Each stage of biosynthesis is catalyzed by a specific enzyme and provided with the energy of ATP.
Process name | Process conditions | Process mechanism | Process results | Process value |
Answer:
Process name | Process conditions | Process mechanism | Process results | Process value |
Protein biosynthesis | Presence of DNA, m (i) RNA, t RNA, enzymes, ATP | RNA synthesis (s), intake m RNA per ribosome, interaction t RNA with a / c and m RNA, detachment of a / c into the synthesized protein chain | Synthesis of a specific protein | Synthesis of the body's own proteins, implementation of hereditary information |
S-3 ... Many identical protein molecules are simultaneously synthesized in the cell. Why do you think? How is this provided by the cell?
Answer:
The cell must have a certain amount of protein in order for it to perform its functions. Lack of protein leads to disruptions in the body's life. Protein synthesis occurs simultaneously on multiple ribosomes (polysomes)
 |  |
Card 40 Topic: Metabolism. |
IN 1. How is plastic metabolism different from energy metabolism?
1) Energy is stored in ATP molecules
2) The energy stored in the ATP molecules is consumed
3) Organic substances are synthesized
4) Degradation of organic substances occurs
5) End products of exchange of carbon dioxide and water
6) As a result of metabolic reactions, proteins are formed
Answer: 2 3 6.
AT 4. Have become a correspondence between the sign of metabolism and its appearance in humans.
Signs of metabolism Type of metabolism
1) oxidation of substances A) plastic
2) synthesis of substances B) energetic
3) energy storage
4) energy consumption
5) participation of ribosomes
6) participation of mitochondria
Card 44 Topic: Energy exchange |
AT 8. Establish a sequence of steps for energy metabolism.
A) cleavage of biopolymers to monomers
B) the entry of organic matter into the cell
C) oxidation of pyruvic acid to
carbon dioxide and water
D) the breakdown of glucose to pyruvic acid
E) synthesis of two ATP molecules
E) synthesis of 36 ATP molecules
Answer: B AGDVE
B) the lysosome merges with a particle of food,C) the breakdown of glucose to pyruvic
acids and the synthesis of two ATP molecules
D) the intake of pyruvic acid in
mitochondria
E) oxidation of pyruvic acid and synthesis
36 ATP molecules
Answer: BAVGD
С-5. Problem. How many ATP molecules are synthesized in cells in the course of glycolysis, if the oxidation of a section of a starch molecule containing 50 glucose residues occurs?
Answer: 1) In the process of glycolysis during oxidation from 1 molecule C6H12O6 up to 2 molecules of starch hammer, 2 ATP molecules are formed.
2) From a fragment of a starch molecule from 50 glucose residues, 100 ATP molecules are formed as a result of glycolysis (50x2 = 100)
С-5. Problem. How many ATP molecules will be synthesized in eukaryotic cells upon complete oxidation of a glycogen molecule fragment consisting of 4 glucose residues?
Answer: In the process of cellular respiration with complete oxidation of 1 molecule C6H2O6 38 ATP molecules are formed. Of the 4 glucose residues, 4x38 = 152 molecules of the ATP chain.
IN 1.
H What happens during photosynthesis?
A) oxygen is absorbed
B) carbon dioxide is released
B) carbon dioxide is absorbed
D) oxygen is released
D) organic matter is formed
E) organic matter is consumed
Answer: 1). IOP
AT 6 . Establish a correspondence between a biological process and its characteristics.
Characteristic | Process |
A-Synthesis of organic substances from nucleotides | 1-Breathing |
B- Oxygen evolution | 2-Photosynthesis |
B- Emission of carbon dioxide |
|
G-Oxygen uptake |
|
D-Oxidation of organic compounds |
|
E - Absorption of carbon dioxide Answer: 221112 |
AT 6. Establish a correspondence between the feature of the process in plants and its type
Process feature Process type
A) occurs in chloroplasts 1.Glycolysis
B) consists of light and dark phases 2.Photosynthesis
C) pyruvic acid is formed
D) occurs in the cytoplasm
E) the final product - glucose
E) glucose breakdown
Answer: A-2, B-2, B-1, G-1, D-2, E-1.
AT 6. Establish a correspondence between the characteristics of autotrophic nutrition and its type.
C-1. The leaves of plants are intensively
the process of photosynthesis. Does it take place in mature
or not ripe fruits?
Answer: 1. Photosynthesis - takes place in all green
parts of the stems, sepal, receptacle, peduncle,
green growing fruits. When the fruits are ripe
chloroform is destroyed by photosynthesis - no.
C-2. P read the text. List the sentence numbers where mistakes were made and explain them.
1. Plants breathe only during the day, in the light. 2. Photosynthesis occurs at the same time. 3. Plants absorb much more carbon dioxide during photosynthesis than they release during respiration. 4. During photosynthesis, plants use the energy of organic matter accumulated by them. 5. During breathing, they use the energy of light. 6. Like animals, plants die when respiration stops.
Answers: Errors were made 1 4 5 sentences.
1. Plants breathe around the clock. 4. In the process of photosynthesis, plants use the energy of sunlight. 5. In the process of respiration, plants use the energy of organic substances created in the process of photosynthesis.
Source of assignments: https://ege.sdamgia.ru/ (decided by themselves)
Exercise 1.
Consider the diagram. Write down the missing term indicated on the diagram with a question mark in the answer.
Explanation: the hypothalamus sends a signal to the pituitary gland (in fact, the hypothalamic-pituitary complex is involved in the production of hormones), which secretes growth hormone.
The correct answer is the pituitary gland.
Task 2.
What sciences study living systems at the organismic level? Choose two correct answers out of five and write down the numbers under which they are indicated.
1. Anatomy
2. Biocenology
3. Physiology
4. Molecular biology
5. Evolutionary teaching
Explanation: at the organismic level, living systems are studied by anatomy (structure of the body) and physiology (internal processes).
The correct answer is 13.
Task 3.
In DNA, nucleotides with adenine account for 18%. Determine the percentage of nucleotides with cytosine that make up the molecules. In the answer, write down only the corresponding number.
Explanation: the share of nucleotides with adenine accounts for 18%. By the principle of complementarity, adenine is associated with thymine, and cytosine with guanine. This means that the amount of nucleotides with thymine is also 18%. Then the share of nucleotides with cytosine and guanine accounts for 100% - (18% + 18%) = 64%.
Divide by 2, we get 32%.
The correct answer is 32%.
Task 4.
Choose two correct answers out of five. In what structures of eukaryotic cells are DNA molecules localized?
1. Cytoplasm
2. The core
3. Mitochondria
4. Ribosomes
5. Lysosomes
Explanation: DNA in eukaryotic cells is contained in the nucleus of a linear molecule (one or more) and in mitochondria (circular mitochondrial DNA), since earlier mitochondria were free-living microorganisms and were built like eukaryotic cells.
The correct answer is 23.
Task 5.
Establish a correspondence between the signs of a cell organoid and the organoid for which these signs are characteristic.
Signs of an organoid
A. Contains green pigment
B. Consists of a double membrane, thylakoids and granules
B. Converts light energy into chemical energy
D. Consists of a double membrane and cristae
E. Provides the final oxidation of nutrients
E. Stores energy in the form of 38 moles of ATP during the breakdown of 1 mole of glucose
Organelles
1. Chloroplast
2. Mitochondria
Explanation:
Chloroplasts are green plastids consisting of a double membrane, thylakoids and granules, they convert the energy of light into the energy of chemical bonds.
Mitochondria are two membrane organelles with cristae (concavities of the inner membrane). In mitochondria, nutrients are oxidized, during which 38 ATP molecules are released per glucose molecule.
The correct answer is 111222.
Task 7.
This list contains cells in which the set of chromosomes is haploid. Identify two signs that "fall out" from the general list, and write down the numbers under which they are indicated in response.
1. Fern sprout cells
2. Cells of the boll of moss
3. Sperm of rye
4. Wheat endosperm cells
5. Horsetail spores
Explanation: The haploid set of chromosomes is contained in the cells of the fern germ (since it develops from a haploid spore), in the sperm of rye (in the germ cells there is a haploid set of chromosomes) and horsetail spores (formed by meiosis). The cells of the boll of moss and the cells of the endosperm of wheat have a diploid set of chromosomes.
The correct answer is 24.
Task 8.
Establish a correspondence between the breeding method and a specific example.
Example
A. Fern spore formation
B. Formation of Chlamydomonas gametes
B. Formation of spores in sphagnum
D. Yeast budding
E. Fish spawning
Breeding method
1. Asexual
2. Sexual
Explanation: asexual reproduction occurs without the participation of germ cells, we include sporulation of fern and sphagnum moss, budding of yeast.
Sexual reproduction takes place with the participation of germ cells, that is, the formation of Chlamydomonas gametes and fish spawning.
The correct answer is 12112.
Task 9.
What are the characteristics of mushrooms? Choose three of the six correct attributes.
1. Autotrophic organisms
2. There is chitin in the cell walls
3. All multicellular
4. Some form mycorrhiza with plants
6. Grow all your life
Explanation: mushrooms are a separate kingdom of living organisms. Their cell walls contain chitin, some of them form mycorrhiza with plants and grow throughout life.
The correct answer is 246.
Task 10.
Establish a correspondence between the characteristics of the organism and the organism to which the given characteristic belongs.
Signs
A. Store carbohydrates in the form of starch
B. Body formed by hyphae
B. The cell wall contains chitin
E. Form spores during reproduction.
E. Reserve substance - glycogen
Organisms
1. Algae
2. Mushrooms
Explanation: algae are lower plants, in their cells carbohydrates are stored in the form of starch, contain a green pigment - chlorophyll and form zoospores during reproduction.
Fungi have a body formed by hyphae, chitin is part of their cell walls, and the storage substance of cells is glycogen.
The correct answer is 122112.
Task 11.
Arrange the bones of the bird's hind legs in the correct order, starting with the spine. Write down the corresponding sequence of numbers in your answer.
1. Tarsus
2. Shin bone
3. Phalanges of fingers
4. Femur
Explanation: consider the picture.
Bones are located from top to bottom: femur - lower leg - tarsus - phalanges of the fingers.
The correct answer is 4213.
Task 12.
Select the signs of a person's unconditioned reflexes.
1. Not inherited
2. Produced in the process of evolution
3. Typical for all individuals of the species
4. Acquired throughout life
5. Passed by inheritance
6. Individual
Explanation: unconditioned reflexes are those reflexes with which certain kind living organisms. They are developed in the process of evolution, are always characteristic of all individuals and are inherited.
The correct answer is 235.
Task 13.
Establish a correspondence between the indicators of human vital functions and the diagnoses of the disease.
Vital signs
A. Avitaminosis C
B. Loss of teeth
B. Increased content of thyroxine in the blood
D. Elevated blood glucose
E. Bulging eyes, goiter
E. Lack of insulin in the blood
Diagnosis
1. Diabetes mellitus
2. Scurvy
3. Basedow's disease
Explanation: diabetes there are several types and is produced when the insulin content is low (insulin is a pancreatic hormone that transfers glucose into cells), without insulin (or when there is a lack of it), glucose accumulates in the blood and ATP is not produced.
Scurvy is a disease of sailors with a lack of vitamin C (vitamin C deficiency), characterized by tooth loss and bleeding gums.
Basedow's disease develops with an increased content of thyroxine in the blood (hyperfunction thyroid gland), characterized by bulging eyes, goiter).
The correct answer is 223131.
Task 14.
Place the bones of the upper limb in the correct order, starting with the shoulder girdle. Write down the corresponding sequence of numbers in your answer.
1. Bones of the metacarpus
2. Shoulder bone
3. Phalanges of fingers
4. Radial bone
5. Bones of the wrist
Explanation: the skeleton of free upper lumbarity looks like this:
That is: humerus, radius, wrist bones, metacarpus bones, phalanges of the fingers.
The correct answer is 24513.
Task 15.
Select the traits that characterize natural selection as the driving force of evolution.
1. Source of evolutionary material
2. Provides a reserve of hereditary variability
3. The object is the phenotype of the individual
4. Provides selection of genotypes
5. Directional factor
6. Factor of accidental action
Explanation: Natural selection- selection, as a result of which (in the natural environment) the organism most adapted to the given environmental conditions survives (forms of selection are distinguished: driving, stabilizing, disruptive).
Natural selection is one of the driving forces behind evolution.
Specifications:
Object - individual phenotype
Provides selection of genotypes
It is a factor of directional action (towards the formation of the most adapted organisms).
The correct answer is 345.
Task 16.
Establish a correspondence between organisms that appeared or flourished in the process of evolution, and the eras in which they appeared and flourished.
Organisms
A. Emergence of the first birds
B. Reptile flourishing
B. Flourishing of shellfish
D. Flourishing insects
E. The flourishing of mammals
E. Distribution of birds
Eras
1. Paleozoic
2. Mesozoic
3. Cenozoic
Explanation: consider the table.
In the Paleozoic, mollusks flourish.
In the Mesozoic - the heyday of reptiles and the appearance of the first birds (Archeopteryx, etc.).
In the Cenozoic - the flourishing of insects and mammals, the spread of birds.
The correct answer is 221333.
Task 17.
What are the characteristics of an agrocenosis? Choose three correct answers out of six and write them down.
1. The natural cycle of substances in this community is disrupted
2. A high number of plants of one species
3. Big number species of plants and animals
4. The leading factor influencing the community is artificial selection
5. Closed circulation of substances
6. Species have different adaptations to cohabitation
Explanation: agrocenosis is an artificial ecosystem created by man. It disrupts the natural circulation of substances (the circulation of substances is not closed), a high number of plants of one species (for example, a potato field), the leading factor is artificial selection.
The correct answer is 124.
Task 18.
Establish a correspondence between the characteristic of the environment and its factor.
Characteristic
A. Constancy of the gas composition of the atmosphere
B. Changing the thickness of the ozone shield
B. Change in air humidity
D. Change in the number of consumers
E. Change in the number of producers
Environmental factors
1. Biotic
2. Abiotic
Abiotic factors - factors of inanimate nature - the constancy of the gas composition of the atmosphere, changes in the thickness of the ozone screen, changes in air humidity.
The correct answer is 111222.
Task 19.
Arrange the gray toad species classification in the correct order, starting with the smallest. Write down the corresponding sequence of numbers in your answer.
1. Class Amphibians
2. Type Chordates
3. Genus of the Toad
4. Kingdom of Animals
5. Squad Tailless
Explanation: we arrange taxa starting with the smallest.
Kind of gray toad
The genus of the Toad
Tailless squad
Class Amphibians
Type Chordates
Kingdom of Animals
The correct answer is 35124.
Task 20.
Insert the missing terms from the proposed list into the text "Nutrition on the sheet", using numbers for this. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (in the text) into the table below.
FOOD IN THE LEAFOrganic matter is formed in the leaf in the process ___________ (A). Then they move along special cells of the conducting tissue - ___________ (B) - to the rest of the organs. These cells are located in a special zone of the stem bark - ___________ (B). This type of plant nutrition was called ___________ (D), since the initial substance for it is carbon dioxide extracted by the plant from the atmosphere.
List of terms:
1. Air
2. Wood
3. Breathing
4. Bast
5. Soil
6. Sieve tube
7. Vessel
8. Photosynthesis
Explanation: Plants are characterized by the process of formation of organic substances from inorganic ones - photosynthesis. Organic substances move through the cells of the conductive tissue - sieve tubes. They are located in the bast. Such plant nutrition is called aerial.
The correct answer is 8641.
Task 21.
Using the Fish Breeding Chart and your knowledge of biology, select the correct statements.
1) The largest average diameter of eggs in pikes.
2) Baltic cod fishermen catch at an immature age.
3) The largest average diameter of eggs in carp and cod.
4) The number of eggs in stickleback is the lowest, since natural selection acts: predators eat, die from diseases and random factors.
5) The carp spawns the largest number of eggs, because these are the largest fish of the indicated representatives.
Explanation: based on the data in the table, pike eggs have the largest average diameter (2.7 mm).
Baltic cod reaches maturity by 5-9 years, and it is caught at 3 years (that is, until maturity).
Statement 3 is wrong.
Statements 4 and 5 may be correct, but we do not have such data (about natural selection and fish size).
The correct answer is 12.
Task 22.
What changes in the forest ecosystem can lead to a decrease in the number of herbivorous mammals?
Explanation: possible consequences:
1. Lack of control of the number of plants (colonization by plants of "poor" areas) - the spread of diseases among plants.
2. Reducing the number of consumers of the 1st order (due to lack of food)
3. Reduction in the number of consumers of the 2nd and 3rd orders (due to the reduction in the number of consumers of the 1st order).
Task 23.
Name the organism shown in the figure and the type to which it belongs. What is indicated by the letters A and B, name the functions of these cells.
Explanation: the picture shows a hydra, Type of intestinal cavities.
Hydra has two layers - outer (ectoderm) and inner (endoderm).
The letter A denotes stinging cells. The hydra releases them to trap and immobilize the victim.
The letter B denotes a digestive muscle cell (function - digestion).
Task 24.
Nay-di-those errors in pri-ve-den-nom text. Indicate the numbers of the pre-lo-s, in which the mistakes were made, explain them.
1. The nasal cavity is lined with ciliated epithelium.
2. The larynx is a funnel-shaped hollow organ.
3. Above-gor-tan-nik closes the entrance to the esophagus.
5. Ka-shel pro-exits with a strong inhalation.
6. Gor-tan pe-re-goes into two large bron-ha.
Explanation: sentence 3 - the epiglottis (epiglottis cartilage) closes the entrance to the larynx, and not to the esophagus.
Proposition 5 - we cough when exhaling strongly, not inhaling (when the airways are narrowed with a cold, for example. But, in general, there can be a lot of reasons for coughing on exhalation).
Proposition 6 - the larynx passes into the trachea, and it divides into two large bronchi.
Task 25.
The adaptability of the skeleton of birds to flight. Indicate at least 4 signs.
Explanation:
1. Hollow bones
2. Double breathing - air sacs
3. Development of the forelimbs into wings
4. Development of feathers
5. Muscular and glandular stomach
6. Keel development
7. Tarsus development
8. Reduction of teeth
9. Reduction of the bladder and right ovary
Task 26.
Indicate examples of the destructive influence of a person on the flora, explain how the harm of influence is expressed. Indicate at least 4 items.
Explanation: the following human actions lead to a decrease in biological diversity:
1. Burning forests (grass, etc.).
2. Deforestation.
3. Plowing up the soil.
4. Destruction of certain plant species.
5. Destruction of plants listed in the Red Book.
6. Destruction of weeds (weeding or the use of special substances - herbicides).
7. Drainage of swamps - destruction of algae, mosses, etc.
8. Contributing to the strengthening of global changes.
Task 27.
There are 42 chromosomes in oat somatic cells. Determine the chromosome set and the number of DNA molecules before the onset of meiosis I and in the metaphase of meiosis II. Explain the answer.
Explanation: oat coamtic cells contain a diploid (double) set of chromosomes, and in the process of meiosis, 4 haploid cells (with a single set of chromosomes) are obtained. At the beginning of meiosis, the number of DNA molecules doubles, that is, it was 2n2c, and now it is 2n4c. By the time of meiosis II metaphase, one division has already occurred, that is, the set remained 1n2c.
Let's take a look at the table.
Task 28.
When crossing maize plants with smooth colored seeds and plants with wrinkled uncolored seeds, the offspring turned out to be smooth and colored seeds. In the analyzing cross of the F1 hybrid, the offspring of two phenotypic groups turned out. Make a scheme for solving the problem. Determine the genotypes of the parents, genotypes and phenotypes of the offspring in crosses. Explain the appearance of two phenotypic groups in F2. What is the law of heredity manifested in F1 and F2?
Explanation: A - smooth seeds
a - wrinkled seeds
B - colored seeds
c - uncolored seeds
In the first cross in the offspring, we get uniformity (all plants with smooth and colored seeds). So the crossing looks like this:
Р1: ААВВ х Аавв
G1: AB x AV
AaBv - smooth colored seeds
Let's carry out an analyzing cross (with a recessive homozygote):
P2: AaBv x aavv
G2: AB, av x ab, since only two phenotypic groups were obtained in the offspring, we conclude that the AB and ab genes are linked
F2: AaBv - smooth colored seeds
aavv - wrinkled uncolored seeds
Choose one correct answer.
A1. There are no mitochondria in cells
thrush
staphylococcus
crucian carp
Golgi complex
ribosomes
mitochondria
chloroplasts
mitochondria
chloroplasts
leukoplasts
chromoplasts
chromosomes
lysosomes
ribosome
ribosomes
Golgi apparatus
lysosomes
1) ribosomes
2) lysosomes
4) chromosomes
A7. The ribosome is an organoid actively involved in
1) protein biosynthesis
2) ATP synthesis
3) photosynthesis
4) cell division
A8. The nucleus in the plant cell discovered
A. Levenguk
R. Hooke
R. Brown
I. Mechnikov
A9. The non-membrane components of the cell include
Golgi apparatus
ribosome
vacuoles
plastids
chromosomes
mitochondria
flagella and cilia
cell center
cell cytoskeleton
contractile vacuoles
bacteria
eukaryotes
prokaryote
bacteriophages
mitochondria and nucleus
vacuoles and the Golgi complex
nuclear membrane and chloroplasts
plasma membrane and ribosomes
protein biosynthesis
spiralization of chromosomes
cytoplasmic movement
fission spindle formation
1) the Golgi complex
2) cell center
3) plastids
4) mitochondria
A16. The term cage was introduced
M. Schleiden
R. Hooke
T. Schwann
R. Virkhov
colibacillus
the simplest
mushrooms
plants
A18. Cells of prokaryotes and eukaryotes differ in the presence
ribosome
lymphocyte
influenza virus
plague bacillus
sulfur bacteria
proteins and nucleic acids
lipids and proteins
only lipids
only carbohydrates
mitochondria
cytoplasm
cell wall
IN 1. Choose three correct answers out of six. An animal cell is characterized by the presence
ribosome
chloroplasts
formed core
cellulose cell wall
Golgi complex
one ring chromosome
IN 2. Choose three correct answers out of six. In what structures of eukaryotic cells are DNA molecules localized?
cytoplasm
mitochondria
ribosomes
chloroplasts
lysosomes
AT 3. Choose three correct answers out of six. A plant cell is characterized by
absorption of solid particles by phagocytosis
the presence of chloroplasts
the presence of a formalized core
the presence of a plasma membrane
lack of cell wall
the presence of one ring chromosome
AT 4. Choose three correct answers out of six. What is the structure and function of mitochondria?
break down biopolymers to monomers
characterized by anaerobic energy production
contain interconnected faces
have enzymatic complexes located on the cristae
oxidize organic matter to form ATP
have outer and inner membranes
AT 5. Choose three correct answers out of six. The similarity of bacterial and animal cells is that they have
shaped core
cytoplasm
mitochondria
plasma membrane
glycocalyx
ribosomes
AT 6. Choose three correct answers out of six. An animal cell is characterized by
1) the presence of vacuoles with cell sap
2) the presence of chloroplasts
3) capture of substances by phagocytosis
4) division by mitosis
5) the presence of lysosomes
6) lack of a formalized core
AT 7. In a plant cell, unlike animal cells, there are
1) ribosomes
2) chloroplasts
3) centrioles
4) plasma membrane
5) cellulose cell wall
6) vacuoles with cell sap
AT 8. Establish a correspondence between a trait and a group of organisms
A) lack of nucleus 1) prokaryotes
B) the presence of mitochondria 2) eukaryotes
C) the absence of EPS
D) the presence of the Golgi apparatus
E) the presence of lysosomes
E) linear chromosomes consisting of DNA and protein
AT 9. Establish a correspondence between the trait of the organism and the kingdom for which this trait is characteristic
A) by the way of nutrition, mainly autotrophs 1) Plants
B) have vacuoles with cell sap 2) Animals
C) the cell wall is absent
D) there are plastids in the cells
E) most are able to move
E) by the way of feeding predominantly heterotrophs
AT 10 O'CLOCK. Establish a correspondence between the presence of the named organelles in bacterial and animal cells.
A) mitochondria 1) animal liver cell
B) cell wall 2) bacterial cell
D) Golgi apparatus
E) nucleoid
E) flagella
AT 11. Establish a correspondence between cell structures and their functions
A) protein synthesis 1) cell membrane
B) lipid synthesis 2) EPS
C) division of the cell into sections (compartments)
G) active transport molecules
E) passive transport of molecules
E) the formation of intercellular contacts
AT 12. Arrange the listed events in chronological order
A) Inventions of the electron microscope
B) Discovery of ribosomes
C) The invention of the light microscope
D) R. Virchow's statement about the appearance of "every cell from a cell"
E) The emergence of the cell theory of T. Schwann and M. Schleiden
F) The first use of the term "cell" by R. Hooke
B13. Establish a correspondence between cell organelles and their functions
A) are located on the granular EPS
B) protein synthesis
B) photosynthesis 1) ribosome
D) a system of two subunits 2) chloroplasts
D) consist of granules with thylakoids
E) form a polysome
C1. Find errors in the text provided, correct them, indicate the numbers of the sentences in which they are made, write down these sentences without errors. 1. All living organisms - animals, plants, fungi, bacteria, viruses - are composed of cells.
2. Any cells have a plasma membrane.
3. Outside of the membrane, the cells of living organisms have a rigid cell wall.
4. All cells have a nucleus.
5. The cell nucleus contains the genetic material of the cell - DNA molecules.
Give a full detailed answer to the question
C2. Prove that the cell is an open system.
C3. What is the role of biological membranes in a cell?
C4. How does ribosome formation occur in eukaryotic cells?
C5. What features of the similarity between mitochondria and prokaryotes made it possible to put forward a symbiotic theory of the origin of the eukaryotic cell?
C6. What is the structure and function of the shell of the kernel?
C7. What features of chromosomes ensure the transmission of hereditary information?
Answers to Level A Questions
| A1 | A2 | A3 | A4 | A5 | A6 | A7 | A8 | A9 | A10 |
| 2 | 1 | 2 | 4 | 1 | 2 | 1 | 3 | 4 | 4 |
| A11 | A12 | A13 | A14 | A15 | A16 | A17 | A18 | A19 | A20 |
| 1 | 2 | 4 | 4 | 1 | 2 | 1 | 1 | 1 | 2 |
Answers to level B tasks
AT 9. 1 A B D
AT 10 O'CLOCK. 1 A C D
AT 11. 1 C D E F
AT 12. C E E D A B
Mitochondria and plastids have their own circular DNA and small ribosomes, due to which they themselves make part of their proteins (semi-autonomous organelles).
Mitochondria take part in (oxidation of organic substances) - they supply ATP (energy) for the vital activity of the cell, they are the “energy stations of the cell”.
Non-membrane organelles
Ribosomes- these are organelles that are engaged. Consist of two subunits, each chemical composition- from ribosomal RNA and proteins. Subunits are synthesized in the nucleolus. Part of the ribosomes are attached to the EPS, this EPS is called rough (granular).
Cell center consists of two centrioles, which form the spindle of division during cell division - mitosis and meiosis.
Cilia, flagella serve for movement.
Choose the one that is most correct. The composition of the cytoplasm of the cell includes
1) protein filaments
2) cilia and flagella
3) mitochondria
4) cell center and lysosomes
Answer
Establish a correspondence between the functions and organelles of cells: 1) ribosomes, 2) chloroplasts. Write down the numbers 1 and 2 in the correct order.
A) are located on the granular EPS
B) protein synthesis
C) photosynthesis
D) consist of two subunits
D) consist of granules with thylakoids
E) form a polysome
Answer
Establish a correspondence between the structure of a cell organoid and an organoid: 1) the Golgi apparatus, 2) the chloroplast. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) two-membrane organoid
B) has its own DNA
B) has a secretory apparatus
D) consists of a membrane, vesicles, cisterns
E) consists of gran and stroma thylakoids
E) one-membrane organoid
Answer
Establish a correspondence between the characteristics and organelles of the cell: 1) chloroplast, 2) endoplasmic reticulum. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) the system of tubules formed by the membrane
B) the organoid is formed by two membranes
B) transports substances
D) synthesizes primary organic matter
E) includes thylakoids
Answer
1. Choose one, the most correct option. Single membrane cell components -
1) chloroplasts
2) vacuoles
3) cell center
4) ribosomes
Answer
2. Choose three options. What cell organelles are separated from the cytoplasm by one membrane?
1) Golgi complex
2) mitochondria
3) lysosome
4) endoplasmic reticulum
5) chloroplast
6) ribosome
Answer
All but two of the signs below can be used to describe the features of the structure and functioning of ribosomes. Identify two signs that "fall out" from the general list, and write down the numbers under which they are indicated.
1) consist of triplets of microtubules
2) participate in the process of protein biosynthesis
3) form a fission spindle
4) formed by protein and RNA
5) consist of two subunits
Answer
Choose two correct answers out of five and write down the numbers under which they are indicated in the table. Select two membrane organelles:
1) lysosome
2) ribosome
3) mitochondria
4) Golgi apparatus
5) chloroplast
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. Plant cells are two-membrane organelles.
1) chromoplasts
2) centrioles
3) leukoplasts
4) ribosomes
5) mitochondria
6) vacuoles
Answer
NUCLEUS1-MITOCHONDRIA1-RIBOSOMA1
Analyze the table. For each cell indicated by letters, select the appropriate term from the list provided:
1) core
2) ribosome
3) protein biosynthesis
4) cytoplasm
5) oxidative phosphorylation
6) transcription
7) lysosome
Answer
MITOCHONDRIA2-CHROMOSOME1-RIBOSOME2 
Analyze the table "Structures of a eukaryotic cell." For each letter cell, select the appropriate term from the list provided.
1) glycolysis
2) chloroplasts
3) broadcast
4) mitochondria
5) transcription
6) core
7) cytoplasm
8) cell center
Answer
LYSOSOMA1-RIBOSOMA3-CHLOROPLAST1 
1) Golgi complex
2) synthesis of carbohydrates
3) single membrane
4) hydrolysis of starch
5) lysosome
6) non-membrane
Answer
LYSOSOMA2-CHLOROPLAST2-RIBOSOMA4 
Analyze the table. For each letter cell, select the appropriate term from the list provided.
1) two-membrane
2) endoplasmic reticulum
3) protein biosynthesis
4) cell center
5) non-membrane
6) biosynthesis of carbohydrates
7) single membrane
8) lysosome
Answer
LIZOSOMA3-AG1-CHLOROPLAST3 
Analyze the table "Cell structures". For each letter cell, select the appropriate term from the list provided.
1) glycolysis
2) lysosome
3) protein biosynthesis
4) mitochondria
5) photosynthesis
6) core
7) cytoplasm
8) cell center
Answer
CHLOROPLAST4-AG2-RIBOSOMA5 
Analyze the table "Cell structures". For each letter cell, select the appropriate term from the list provided.
1) oxidation of glucose
2) ribosome
3) cleavage of polymers
4) chloroplast
5) protein synthesis
6) core
7) cytoplasm
8) fission spindle formation
Answer
AG3-MITOCHONDRIA3-LYSOSOMA4 
Analyze the table "Cell organelles". For each letter cell, select the appropriate term from the list provided.
1) chloroplast
2) endoplasmic reticulum
3) cytoplasm
4) karyoplasm
5) Golgi apparatus
6) biological oxidation
7) transport of substances in the cell
8) glucose synthesis
Answer
1. Choose two correct answers out of five and write down the numbers under which they are indicated in the table. The cytoplasm performs a number of functions in the cell:
1) communicates between the nucleus and organelles
2) serves as a matrix for the synthesis of carbohydrates
3) serves as the location of the nucleus and organelles
4) carries out the transfer of hereditary information
5) serves as the location of chromosomes in eukaryotic cells
Answer
2. Identify two true statements from the general list, and write down the numbers under which they are indicated. In the cytoplasm occurs
1) synthesis of ribosome proteins
2) biosynthesis of glucose
3) insulin synthesis
4) oxidation of organic substances to inorganic
5) synthesis of ATP molecules
Answer
Choose two correct answers out of five and write down the numbers under which they are indicated. Select non-membrane organelles:
1) mitochondria
2) ribosome
3) core
4) microtubule
5) Golgi apparatus
Answer
The features listed below, except for two, are used to describe the functions of the depicted organoid of the cell. Identify two signs that "fall out" from the general list, and write down the numbers under which they are indicated.
1) serves as a power station
2) breaks down biopolymers into monomers
3) provides packing of substances from the cage
4) synthesizes and accumulates ATP molecules
5) participates in biological oxidation
Answer
Establish a correspondence between the structure of an organoid and its type: 1) cell center, 2) ribosome
A) consists of two perpendicularly located cylinders
B) consists of two subunits
B) formed by microtubules
D) contains proteins that ensure the movement of chromosomes
E) contains proteins and nucleic acid
Answer
Establish the sequence of the arrangement of structures in the eukaryotic cell of the plant (starting from the outside)
1) plasma membrane
2) cell wall
3) core
4) cytoplasm
5) chromosomes
Answer
Choose three options. How are mitochondria different from lysosomes?
1) have outer and inner membranes
2) have numerous outgrowths - cristae
3) participate in the processes of energy release
4) in them, pyruvic acid is oxidized to carbon dioxide and water
5) they decompose biopolymers to monomers
6) participate in metabolism
Answer
1. Establish a correspondence between the characteristics of a cell organoid and its type: 1) mitochondria, 2) lysosome. Write down the numbers 1 and 2 in the correct order.
A) one-membrane organoid
B) inner content - matrix
D) the presence of cristae
E) semi-autonomous organoid
Answer
2. Establish a correspondence between the characteristics and organelles of the cell: 1) mitochondria, 2) lysosome. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) hydrolytic degradation of biopolymers
B) oxidative phosphorylation
C) one-membrane organoid
D) the presence of cristae
E) the formation of a digestive vacuole in animals
Answer
3. Establish a correspondence between the trait and the cell organoid, for which it is characteristic: 1) lysosome, 2) mitochondria. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) the presence of two membranes
B) energy storage in ATP
C) the presence of hydrolytic enzymes
D) digestion of cell organelles
E) the formation of digestive vacuoles in protozoa
E) splitting organic matter to carbon dioxide and water
Answer
Establish a correspondence between the organoid of the cell: 1) the cell center, 2) the contractile vacuole, 3) the mitochondrion. Write down the numbers 1-3 in the correct order.
A) participates in cell division
B) synthesis of ATP
B) excretion of excess fluid
D) "cellular respiration"
E) maintaining the constancy of cell volume
E) participates in the development of flagella and cilia
Answer
1. Establish a correspondence between the name of organelles and the presence or absence of a cell membrane in them: 1) membrane, 2) non-membrane. Write down the numbers 1 and 2 in the correct order.
A) vacuoles
B) lysosomes
B) cell center
D) ribosomes
D) plastids
E) Golgi apparatus
Answer
2. Establish a correspondence between cell organelles and their groups: 1) membrane, 2) non-membrane. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) mitochondria
B) ribosomes
B) centrioles
D) Golgi apparatus
D) endoplasmic reticulum
E) microtubules
Answer
3. Which three of the listed organelles are membranous?
1) lysosomes
2) centrioles
3) ribosomes
4) microtubules
5) vacuoles
6) leukoplasts
Answer
1. All but two of the cell structures listed below do not contain DNA. Identify two structures of the cell that "drop out" from the general list, and write down the numbers under which they are indicated.
1) ribosomes
2) Golgi complex
3) cell center
4) mitochondria
5) plastids
Answer
2. Select three cell organelles containing hereditary information.
1) core
2) lysosomes
3) Golgi apparatus
4) ribosomes
5) mitochondria
6) chloroplasts
Answer
3. Choose two correct answers out of five. In what structures of eukaryotic cells are DNA molecules localized?
1) cytoplasm
2) core
3) mitochondria
4) ribosomes
5) lysosomes
Answer
Choose the one that is most correct. Where there are ribosomes in the cell, except for EPS
1) in the centrioles of the cell center
2) in the Golgi apparatus
3) in mitochondria
4) in lysosomes
Answer
What are the features of the structure and functions of ribosomes? Choose the three correct options.
1) have one membrane
2) consist of DNA molecules
3) break down organic matter
4) consist of large and small particles
5) participate in the process of protein biosynthesis
6) are composed of RNA and protein
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. The structure of the nucleus of a eukaryotic cell includes
1) chromatin
2) cell center
3) Golgi apparatus
4) nucleolus
5) cytoplasm
6) karyoplasm
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. What processes take place in the cell nucleus?
1) the formation of a fission spindle
2) the formation of lysosomes
3) doubling of DNA molecules
4) synthesis of mRNA molecules
5) the formation of mitochondria
6) the formation of ribosome subunits
Answer
Establish a correspondence between the organoid of the cell and the type of structure to which it belongs: 1) one-membrane, 2) two-membrane. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) lysosome
B) chloroplast
C) mitochondria
D) EPS
D) Golgi apparatus
Answer
Establish a correspondence between characteristics and organelles: 1) chloroplast, 2) mitochondria. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) the presence of stacks of grains
B) synthesis of carbohydrates
C) dissimilation reactions
D) transport of electrons excited by photons
D) synthesis of organic substances from inorganic
E) the presence of numerous cristae
Answer
All but two of the features listed below can be used to describe the cell organoid shown in the figure. Identify two signs that "fall out" from the general list, and write down the numbers under which they are indicated.
1) one-membrane organoid
2) contains fragments of ribosomes
3) the shell is permeated with pores
4) contains DNA molecules
5) contains mitochondria
Answer
The terms listed below, in addition to two, are used to characterize the cell organoid indicated in the figure question mark... Identify two terms "falling out" from the general list, and write down the numbers under which they are indicated.
1) membrane organoid
2) replication
3) the divergence of chromosomes
4) centrioles
5) fission spindle
Answer
Establish a correspondence between the characteristics of a cell organoid and its type: 1) cell center, 2) endoplasmic reticulum. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) transports organic matter
B) forms a fission spindle
B) consists of two centrioles
D) one-membrane organoid
E) contains ribosomes
E) non-membrane organoid
Answer
1. Establish a correspondence between the characteristics and organelles of the cell: 1) nucleus, 2) mitochondria. Write down the numbers 1 and 2 in the order corresponding to the numbers.
A) closed DNA molecule
B) oxidative enzymes on cristae
C) internal contents - karyoplasm
D) linear chromosomes
E) the presence of chromatin in the interphase
E) folded inner membrane
Answer
2. Establish a correspondence between the characteristics and organelles of cells: 1) nucleus, 2) mitochondria. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) is the site of ATP synthesis
B) is responsible for storing the genetic information of the cell
B) contains circular DNA
D) has cristae
E) has one or more nucleoli
Answer
Establish a correspondence between the signs and organelles of the cell: 1) lysosome, 2) ribosome. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) consists of two subunits
B) is a single membrane structure
C) participates in the synthesis of the polypeptide chain
D) contains hydrolytic enzymes
D) is located on the membrane of the endoplasmic reticulum
E) converts polymers to monomers
Answer
Establish a correspondence between characteristics and cellular organelles: 1) mitochondria, 2) ribosome. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) non-membrane organoid
B) having your own DNA
B) function - protein biosynthesis
D) consists of large and small subunits
D) the presence of cristae
E) semi-autonomous organoid
Answer
All but two of the features listed below are used to describe the cell structure shown in the figure. Identify two signs that "fall out" from the general list, and write down the numbers under which they are indicated.
1) consists of RNA and proteins
2) consists of three subunits
3) synthesized in the hyaloplasm
4) carries out protein synthesis
5) can be attached to the EPS membrane
Answer
© D.V. Pozdnyakov, 2009-2019
In their own way chemical structure DNA ( Deoxyribonucleic acid) is an biopolymer, the monomers of which are nucleotides... That is, DNA is polynucleotide... Moreover, a DNA molecule usually consists of two chains, twisted relative to each other along a helical line (often called "spirally twisted") and connected by hydrogen bonds.
The chains can be twisted both to the left and to the right (most often) side.
Some viruses have a single strand of DNA.
Each DNA nucleotide consists of 1) a nitrogenous base, 2) deoxyribose, 3) a phosphoric acid residue.
Double right handed DNA helix
DNA includes the following: adenine, guanine, thymine and cytosine... Adenine and guanine belong to purinam, and thymine and cytosine - to pyrimidine... Sometimes DNA contains uracil, which is usually characteristic of RNA, where it replaces thymine.
The nitrogenous bases of one chain of the DNA molecule are connected with the nitrogenous bases of the other strictly according to the principle of complementarity: adenine only with thymine (form two hydrogen bonds with each other), and guanine only with cytosine (three bonds).
The nitrogenous base in the nucleotide itself is connected to the first carbon atom of the cyclic form deoxyribose which is pentose (a carbohydrate with five carbon atoms). The bond is covalent, glycosidic (C-N). Unlike ribose, deoxyribose lacks one of the hydroxyl groups. The deoxyribose ring is formed by four carbon atoms and one oxygen atom. The fifth carbon atom is located outside the ring and is connected through an oxygen atom with the remainder of phosphoric acid. Also, through the oxygen atom at the third carbon atom, the phosphoric acid residue of the adjacent nucleotide is attached.
Thus, in one DNA strand, adjacent nucleotides are linked by covalent bonds between deoxyribose and phosphoric acid (phosphodiester bond). A phosphate-deoxyribose backbone is formed. Perpendicular to it, towards the other DNA strand, nitrogenous bases are directed, which are connected to the bases of the second chain by hydrogen bonds.
The structure of DNA is such that the backbones of hydrogen-bonded chains are directed in different directions (they say "multidirectional", "antiparallel"). On the side, where one ends with phosphoric acid linked to the fifth carbon atom of deoxyribose, the other ends with a "free" third carbon atom. That is, the skeleton of one chain is turned upside down relative to the other. Thus, 5 "ends and 3" ends are distinguished in the structure of DNA strands.
When replicating (doubling) DNA, the synthesis of new strands always goes from their 5th end to the third, since new nucleotides can only attach to the free third end.
Ultimately (indirectly through RNA), every three consecutive nucleotides in the DNA chain encode one amino acid of the protein.
The discovery of the structure of the DNA molecule took place in 1953 thanks to the works of F. Crick and D. Watson (which was also facilitated by the early work of other scientists). Although DNA was known as a chemical as early as the 19th century. In the 40s of the XX century, it became clear that it is DNA that is the carrier of genetic information.
The double helix is considered a secondary structure of the DNA molecule. In eukaryotic cells, the overwhelming amount of DNA is located in chromosomes, where it is bound to proteins and other substances, and also undergoes a denser packing.