Organisms that have a nucleus in their cells. Organisms whose cells have a separate nucleus are called. Do all eukaryotic cells have a nucleus?

2731. Indicate one of the provisions of the cell theory
A) The unit of structure, life activity and development of organisms is the cell
B) The germ cell contains one allele of each gene
C) A multicellular embryo is formed from the zygote
D) In the nuclei of eukaryotic cells, genes are located linearly on chromosomes

Abstract

2732. How many autosomes are contained in a human sperm?
A) 22
B) 2
B) 23
D) 4

Abstract

2733. Organisms whose cells have a separate nucleus are
A) eukaryotes
B) bacteria
B) prokaryotes
D) viruses

Abstract

2734. Parthenogenesis is a type of sexual reproduction in which a new organism develops from
A) diploid zygote
B) the first blastomeres
B) haploid spore
D) unfertilized egg

Abstract

2735. The skin of tomato fruits can be smooth and pubescent (a). Select
genotypes of parent plants that have dominant phenotypes.
A) Aa, aa
B) Aa, Aa
B) A, a
D) AA, aa

Abstract

2736. Inheritance of the hemophilia gene, located on the X chromosome in humans, is an example
A) manifestations of the result of crossing over
B) sex-linked inheritance
B) independent inheritance of traits
D) intermediate inheritance of traits

2737. The appearance of different alleles of one gene occurs as a result
A) indirect cell division
B) modification variability
B) mutation process
D) combinative variability

2738. Why are bacteria classified as an independent kingdom of the organic world?
A) under unfavorable conditions they reproduce by mitosis
B) absence of a nucleus in the cell
B) reproduce by spores
D) mostly heterotrophic organisms

Abstract

2739. The growth of the stem of a woody plant in thickness occurs due to cell division and growth
A) cambium
B) wood
B) traffic jams
D) bast

2740. Angiosperms are more highly organized plants than gymnosperms, since they form
A) zygote during the fusion of gametes
B) seeds from ovules
B) fruits with seeds
D) embryo protected by the seed coat

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Special purpose organelles are found in many plant and animal cells. These include organelles of movement (myofibrils, cilia, flagella, stinging capsules, etc.), supporting structures (tonofibrils), organelles that perceive external stimuli (for example, photoreceptors, stator receptors and phonoreceptors), neurofibrils, as well as cell surface structures associated with absorption and digestion of food (microvilli, cuticle, etc.)

Cilia and flagella - these are organelles protruding from the cell, having a diameter of about 0.25 microns and containing in the middle a bundle of parallel microtubules. The main function of these organelles is to move the cells themselves or to move the surrounding fluid and particles along the cells. Cilia and flagella are present on the surface of many types of cells and are found in most animals and some plants. In humans, bronchial epithelial cells have many cilia (up to 10#9 per 1 cm2). They cause a layer of mucus with dust particles and the remains of dead cells to constantly move upward. With the help of the cilia of the oviduct cells, the eggs move along it. Flagella differ from cilia only in length. Thus, mammalian sperm have one flagellum up to 100 microns long.

Organisms whose cells do not have membrane-bound nuclei.

Typically, cilia are more than 10 times shorter than flagella. Thousands of cilia of one cell move in a coordinated manner, forming traveling waves on the surface of the plasma membrane. Each cilium works like a whip: a forward blow, in which the cilium fully straightens and transmits maximum force to the surrounding fluid, pushing it, and then, bending to reduce the resistance of the medium, it returns to the original position). Microtubules—hollow protein cylinders with an outer diameter of 25 nm—stretch along the entire length of the cilium or flagellum. Microtubules, like microfilaments, are polar; they elongate at one end due to the polymerization of the globular protein. In cilia and flagella they are arranged according to the 9+2 system; nine double microtubules (doublets) form the wall of a cylinder, in the center of which there are two single microtubules. The doublets are able to slide relative to each other, which causes the cilium or flagellum to bend.

Microtubules

Microtubules - protein intracellular structures that make up the cytoskeleton. Microtubules are hollow cylinders with a diameter of 25 nm. Their length can range from several micrometers to probably several millimeters in the axons of nerve cells. Their wall is formed by tubulin dimers. Microtubules, like actin microfilaments, are polar: microtubule self-assembly occurs at one end, and disassembly occurs at the other. In cells, microtubules play the role of structural components and are involved in many cellular processes, including mitosis, cytokinesis and vesicular transport. Contents [show]

Structure of Microtubules are structures in which 13 tubulin α-/β-heterodimers are arranged around the circumference of a hollow cylinder. The outer diameter of the cylinder is about 25 nm, the inner diameter is about 15. One of the ends of the microtubule, called the plus end, constantly attaches free tubulin to itself. From the opposite end - the minus end - tubulin units are split off.

Function Microtubules in the cell are used as “rails” for transporting particles. Membrane vesicles and mitochondria can move along their surface. Transportation along microtubules is carried out by proteins called motor proteins. These are high-molecular compounds consisting of two heavy (weighing about 300 kDa) and several light chains. Heavy chains have head and tail domains. The two head domains bind to microtubules and act as motors themselves, while the tail domains bind to organelles and other intracellular structures to be transported.

In addition to their transport function, microtubules form the central structure of cilia and flagella - the axoneme. A typical axoneme contains 9 pairs of united microtubules at the periphery and two complete microtubules in the center. Microtubules also consist of centrioles and the spindle, which ensures the divergence of chromosomes to the poles of the cell during mitosis and meiosis. Microtubules are involved in maintaining cell shape and the location of organelles (in particular, the Golgi apparatus) in the cytoplasm of cells.

ORGANOIDS FOR SPECIAL PURPOSE

Microtubules – long thin hollow cylinders with a diameter of 25 nm. microtubule walls are made of proteins	1. supporting function - forming an internal frame that helps cells maintain their shape 2. motor - part of cilia and flagella
Mvyrosikroniti – thin structures consisting of thousands of protein molecules connected to each other	They form a musculoskeletal system called the cytoskeleton. promotes cytoplasmic flow in cells
Eyelashes – numerous cytoplasmic projections on the membrane surface are formed by membrane-covered microtubules	Ensure the movement of some single-celled organisms and the flow of fluid in organisms and the removal of dust particles
Flagella– a surface structure present in many prokaryotic and eukaryotic cells and serving for their movement in a liquid environment or on the surface of solid media. The flagella of prokaryotes and eukaryotes differ sharply: the bacterial flagellum has a thickness of 10-20 nm and a length of 3-15 µm, it is passively rotated by a motor located in the membrane; flagella of eukaryotes are up to 200 nm thick and up to 200 microns long; they can independently bend along their entire length. Eukaryotes often also have cilia, identical in structure to the flagellum, but shorter (up to 10 µm).	Serve for the movement of single-celled organisms, sperm and zoospores

Question 17.

Inclusions– optional components of the cell that appear and disappear depending on the metabolic state of the cell.

This is an accumulation of substances in a cell.

Classification:

Trophic (neutral lipids, polysaccharides, proteins)

Secretory (vacuoles that remove substances from the cell)

Excretory (metabolic products)

Pigment - exogenous (carotene, dust, dyes)

- endogenous (hemoglobin, melanin)

Eukaryotes are organisms whose cells have a nucleus surrounded by a membrane.

Features of the structure:

The shape of the cells is varied, the sizes range from 5 to 100 microns.
Cells have similar chemical composition and metabolism.
Cells are divided by a system of membranes into compartments.
The genetic material is concentrated mainly in chromosomes, which have a complex structure and are formed by DNA strands and histone protein molecules.
The cytoplasm contains membrane organelles and centrioles.
Cell division is mitotic.

Core– an obligatory structural component of every eukaryotic cell containing genetic material. In animal cells, hereditary information is stored in nucleus and mitochondria. In plant cells - in the core, mitochondria and plastids. The core consists of:

1. Nuclear envelope;

2. Karyoplasm;

3. Chromatin;

4. Nucleolus.

The shape of the nucleus depends on the shape of the cell itself and the functions it performs.

The size of the nucleus also mainly depends on the size of the cell.

Nuclear-cytoplasmic index – ratio of the volumes of the nucleus and cytoplasm. A change in this ratio is one of the causes of cell division or metabolic disorders.

Nuclear envelope the interphase core consists of two elementary membranes (outer and inner); between them there is a perinuclear space, which is connected through the channels of the endoplasmic reticulum to different parts of the cytoplasm. Both nuclear membranes are permeated at times, through which selective exchange of substances occurs between the nucleus and the cytoplasm. The inside of the nuclear membrane is covered with a protein mesh - nuclear lamina, which determines the shape and volume of the nucleus. Toward the nuclear lamina telomeric regions join chromatin threads. Microfilments form the inner core of the nucleus.

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The internal “skeleton” of the nucleus is of great importance for ensuring the orderly flow of basic processes transcription, replication, processing. The outside of the core is also covered microfilaments, which are elements cell cytoskeleton. The outer nuclear membrane has on its surface ribosomes and associated with membranes endoplasmic reticulum. The nuclear envelope has selective permeability. The flow of substances is regulated by the specific features of membrane proteins and nuclear pores (from 1000 to 10000).

Basic functions of the nuclear membrane.

1. Formation of a cell compartment where the genetic material is concentrated and conditions are created for its preservation and doubling.

2. Separation of the contents of the nucleus from the cytoplasm.

3. Maintaining the shape and volume of the core.

4. Regulation of substance flows (various types of RNA and ribosomal subunits enter the cytoplasm from the nucleus through pores, and the necessary proteins, water, and ions are transferred to the middle of the nucleus).

Karyoplasm – a homogeneous structureless mass that fills the space between chromatin and nucleoli. It contains water (75-80%), proteins, nucleotides, amino acids, ATP, various types of RNA, ribosomal subparticles, intermediate metabolic products and interconnects the structures of the nucleus and cytoplasm.

Chromatin

The genetic material in the interphase nucleus is in the form

intertwined chromatin threads. It is a complex of DNA and proteins (deoxyribonucleoprotein- DNP). During the process of mitosis, spiraling, chromatin forms clearly visible, intensely stained structures. – CHROMOSOMES.

Nucleoli(one or more) – granular, round, highly stained structures that do not have a membrane. Nucleoli are composed of proteins, RNA, lipids and enzymes. The DNA content is no more than 15% and is located mainly in its center.

Nucleoli are fragmented at the beginning of cell division and restored after its completion. In the nucleoli there are 3 plots:

1. Fibrillar;

2. Granular;

3. Lightly colored.

— Fibrillar region of the nucleolus consists of strands of RNA. This is the site of active synthesis of ribosomal RNA on rRNA genes along the DNA molecule of decondensed chromatin.

— Granular area consists of RNA particles similar to ribosomes in the cytoplasm. It is the site where RNA and ribosomal proteins combine to form mature small and large ribosomal subunits.

— Lightly colored area The nucleolus contains DNA (inactive) that is not transcribed.

The formation of nucleoli is associated with secondary constrictions of metaphase chromosomes (nucleolar organizers), in the region of which genes encoding r-RNA synthesis are localized. In human cells, these functions are performed by chromosomes No. 13, 14, 15, 21, 22, which have satellites or companions.

Main functions of nucleoli:

Synthesis of ribosomal RNA.
Formation of ribosomal subunits.

KERNEL FUNCTIONS:

1. Storage and transmission of hereditary information;

2. Regulation of all cell vital processes;

3. DNA repair;

4. Synthesis of all types of RNA;

5. Formation of ribosomes;

6. Implementation of hereditary information by regulating protein synthesis.

CHROMOSOMES.

Chromosomes – thread-like structures, clearly visible in a light microscope only during cell division, are formed from chromatin during the process of its condensation. Depending on the degree condensation chromatin is divided into:

1. Heterochromatin - strong spiralized and genetically inactive, revealed in the form of strongly colored dark areas of the nucleus.

2. Euchromatin – low condensed, genetically active, is detected in the form of light areas of the nucleus.

Chemical composition of chromosomes :

1. DNA – 40%

2. Basic or histone proteins – 40%

3. Non-histone (acidic or neutral) – 20%

4. Traces of RNA, lipids, polysaccharides, metal ions.

Eukaryotes are the most progressively organized organisms. In our article we will look at which of the representatives of living nature belongs to this group and what organizational features allowed them to occupy a dominant position in the organic world.

Who are eukaryotes

According to the definition of the concept, eukaryotes are organisms whose cells contain a formed nucleus. These include the following kingdoms: Plants, Animals, Fungi. And it doesn’t matter how complex their body is. Microscopic amoeba, Volvox colonies - they are all eukaryotes.

Although cells of real tissues can sometimes lack a nucleus. For example, it is not found in red blood cells. Instead, this blood cell contains hemoglobin, which carries oxygen and carbon dioxide. Such cells contain a nucleus only in the first stages of their development. Then this organelle is destroyed, and at the same time the ability of the entire structure to divide is lost. Therefore, having fulfilled their functions, such cells die.

Structure of eukaryotes

All eukaryotic cells have a nucleus. And sometimes not even one. This double-membrane organelle contains in its matrix genetic information encrypted in the form of DNA molecules. The core consists of a surface apparatus, which ensures the transport of substances, and a matrix, its internal environment. The main function of this structure is the storage of hereditary information and its transmission to daughter cells formed as a result of division.

The internal environment of the kernel is represented by several components. First of all, this is karyoplasm. It contains nucleoli and chromatin threads. The latter consist of proteins and nucleic acids. It is during their spiralization that chromosomes are formed. They are directly carriers of genetic information. Eukaryotes are organisms that, in some cases, can form two types of nuclei: vegetative and generative. A striking example of this is ciliates. Its generative nuclei carry out the preservation and transmission of the genotype, and its vegetative nuclei - regulation

Main differences between pro- and eukaryotes

Prokaryotes do not have a formed nucleus. The only thing that belongs to this group of organisms is Bacteria. But this structural feature does not mean at all that there are no carriers of genetic information in the cells of these organisms. Bacteria contain circular DNA molecules called plasmids. However, they are located in the form of clusters in a certain place in the cytoplasm and do not have a common membrane. This structure is called a nucleoid. There is one more difference. The DNA in prokaryotic cells is not associated with nuclear proteins. Scientists have established the existence of plasmids in eukaryotic cells. They are found in some semi-autonomous organelles, such as plastids and mitochondria.

Progressive structural features

Eukaryotes include organisms that are distinguished by more complex structural features at all levels of organization. First of all, this concerns the method of reproduction. provides the simplest of them - in two. Eukaryotes are organisms that are capable of all types of reproduction of their own kind: sexual and asexual, parthenogenesis, conjugation. This ensures the exchange of genetic information, the appearance and consolidation of a number of useful traits in the genotype, and therefore better adaptation of organisms to constantly changing environmental conditions. This feature allowed eukaryotes to occupy a dominant position in

So, eukaryotes are organisms whose cells have a formed nucleus. These include plants, animals and fungi. The presence of a core is a progressive structural feature that ensures a high level of development and adaptation.

a) prokaryotes, b) eukaryotes; c) nucleotides; d) mitochondria; e) nuclear

How many groups are all organisms with a cellular structure divided into?

a) 1, b) 2, c) 3, d) 4, e) 5.

Which cell does not have an organized nucleus and contains only one chromosome?

a) nuclear; b) eukaryotic; c) nucleotide; d) mitochondria; e) prokaryotic

Prokaryotic cells, like eukaryotic cells, are covered with what?

a) mitochondria; b) nucleotides; c) plasma membrane; d) chromosome; e) cell membrane

Structure consisting of DNA, proteins and RNA

a) eukaryotes; b) analogue of the core; c) prokaryotes; d) mitochondria; e) nucleoid

Prenuclear organisms whose cells do not have a membrane-enclosed nucleus

a) prokaryotes; b) eukoryotes; c) membrane; d) plasmolysis; e) nucleoids

An elementary unit of structure and vital activity of all organisms, except viruses

a) nucleoid; b) cocci; c) eukaryotes; d) golgi; e) cell

Photosynthesis pigment

a) prochloro; b) chlorophyll; c) n bacteriorhodopsin; d) murein; e) plasmolysis

Find a sentence with a participial phrase

a) " Milk is an amazing food prepared by nature itself,” wrote academician I. P. Pavlov.

b) Cream differs from milk in its increased content of milk fat.

d) The average milk fat content in milk is 3.9%.

Find a sentence with an adverbial phrase

a) The safety indicators indicated are general for dairy products.

b) Balls the size of a walnut are made from a homogeneous mass and laid out, covered with gauze, in the sun.

c) Cream is obtained by separating milk.

d) Based on the type of heat treatment, milk is classified into pasteurized and sterilized.

e) Kaymak–a fermented milk product similar to sour cream.

TOPIC No. 4

Classification (systematics) of microorganisms.

Syntax of scientific style of speech. Syntactic features of scientific style: complex sentences, participial and adverbial phrases. Introductory words and phrases as means of connecting parts of the text

Glossary

Bacteria– prokaryotic, predominantly unicellular microorganisms that can also form associations (groups) of similar cells, characterized by cellular, but not organismal, similarities.

Culture– a collection of bacteria visible to the eye on nutrient media. Cultures can be pure (a collection of bacteria of one species) or mixed (a collection of bacteria of two or more species).

Clone- a collection of bacteria that are the offspring of one cell.

Taxonomy– section of biology, the task of which is to describe and designate all existing and extinct organisms, as well as their classification into taxa (groupings) of various ranks

Practical tasks

Exercise 1. Read the text, complete the post-text tasks.

Classification (systematics) of microorganisms

The main task of the classification and taxonomy of microorganisms is their distribution based on the similarity of certain characteristics into groups called taxa, as well as the establishment of related relationships between them. The assignment of scientific names to these groups is the nomenclature of microorganisms.

All microorganisms are divided into cellular and non-cellular. Non-cellular microorganisms include viruses, viroids and prions.

The cellular forms of microorganisms are divided into eukaryotes and prokaryotes. Eukaryotes are divided into microhybes and protozoa. Prokaryotes include bacteria, which are divided into two groups: eubacteria and archaebacteria.

Eubacteria, in turn, are divided into gram-positive (thick-walled), gram-negative (thin-walled) and bacteria without a cell wall (mycoplasma).

Thin-walled bacteria include cocci, rods, convoluted (spirilla and spirochetes), rickettsia and chlamydia. Thick-walled include cocci, rod-shaped and actinomycetes

Microbes are included in the kingdom Procariotae, which is divided into divisions, divisions into classes, classes into orders, families, genera, and species. The highest taxon is a kingdom, and the lowest is a species of microorganism.

In microbiology, the terms “strain” and “clone” are widely used.

Strain is a narrower concept than species. Strains are different microbial cultures of the same species isolated from different sources or even from the same source, but at different times.

Clone is a culture of microorganisms obtained from one cell.

1.1. Write out the terms from the text and give them an interpretation.

1.2. Parse the highlighted sentences.

1.3. Extract simple complex sentences from the text and transform them into NGNs.

1.4. Compose a text cluster and prepare a short retelling.

Task 2. Read this information and answer the questions.

Remember! Syntactic features of scientific style.

A specific feature of scientific speech is completeness, completeness and logical consistency of presentation, close connection individual sentences and sections of text.

The basic structure of a scientific text is a declarative sentence with the correct word order and conjunction between parts of a sentence. The informative richness of such texts requires complex syntactic structures. Therefore, in scientific texts they are widely used complex sentences; sentences with isolated members, expressed participial and participial phrases; sentences with homogeneous members with the nature of enumeration.

Working with a scientific text (writing a report, abstract, annotation, review, etc.) involves modifying and transforming sentences. The synonymy of simple and complex sentences is varied. The same thought can be expressed in different ways. In this case, parallel syntactic structures can be used.

Parallel syntactic constructions are constructions that are close in meaning, but expressed by different syntactic units. Usually parallel syntactic constructions are formed subordinate clauses and members of a simple sentence.

Various types are common in scientific texts complex proposals , in particular using compound subordinating conjunctions, which is generally characteristic of book speech: due to the fact that they serve; due to the fact that, while etc. By means of connecting parts of the text introductory words and combinations: firstly, finally, on the other hand, indicating the sequence of presentation. To combine parts of the text, in particular paragraphs that have a close logical connection with each other, words and phrases, demonstrative and personal pronouns indicating this connection are used: so in conclusion, this one, he etc. Sentences in a scientific style are monotonous in terms of the purpose of the statement - they are almost always narrative. Interrogative the sentences are not typical, but are possible to attract attention to what is being presented.

Most often the sentences are complicated involved, participial rpm and separate definitions.

The generalized abstract nature of scientific speech and the timeless plan for presenting the material determine the use of certain types of syntactic constructions: vague-personal, generalized-personal and impersonal sentences. The character in them is absent or is thought of in a generalized, vague way; all attention is focused on the action and its circumstances. Vaguely personal and generalized personal sentences are used when introducing terms, deriving formulas, and explaining material in examples: speed is represented by a directed segment; Consider the following example; Let's compare offers.

Task 3. Read the text, complete the post-text tasks.

Taxonomy of microorganisms

Natural (phylogenetic) taxonomy of microorganisms. The basic category of any biological classification, reflecting a certain stage of evolution of a separate population of organisms, is a species - a set of individuals with the same phenotype, producing fertile offspring and living in a certain area. To correctly understand the meaning of this term in the classification of microorganisms, it is necessary to know the differences in speciation between bacteria and higher plants and animals with obligatory sexual reproduction. The latter species are characterized by the presence of populations with a relatively homogeneous set of genes formed as a result of crossbreeding. If individual parts of a population are isolated from each other (for example, geographically), then their divergent evolution is quite possible. After a certain time, physiological isolation is superimposed on geographic isolation, leading to the development of individual parts of the population along their own path and the formation of a new species. Unlike higher plants and animals, most microorganisms are not able to reproduce sexually. In other words, they lack mechanisms that can lead to “discontinuous” speciation. Thus, the definition of species, as applied to organisms with sexual reproduction, cannot be fully applied to microorganisms. In this regard, the concept of species is interpreted arbitrarily for them.

Until now, there are no unified principles and approaches to combining (or dividing) them into various taxonomic units, although they are trying to use the similarity of genomes as a generally accepted criterion. Many microorganisms have the same morphological characteristics, but differ in the structure of their genomes; the relationships between them are often unclear, and the evolution of many is simply unknown. In addition, microorganisms differ significantly in their architecture, biosynthetic systems, and organization of the genetic apparatus. They are divided into groups to demonstrate the degree of similarity and the assumed evolutionary relationship. The basic feature used to classify microorganisms is the type of cellular organization.

Microorganisms are organisms that are invisible to the naked eye due to their small size. This criterion is the only one that unites them. Otherwise, the world of microorganisms is even more diverse than the world of macroorganisms.

According to modern taxonomy, microorganisms belong to three kingdoms: Vira - these include viruses; Eucariotae – these include protozoa and fungi; Procariotae - these include true bacteria, rickettsia, chlamydia, mycoplasmas, spirochetes, actinomycetes.

3.1. Make a detailed question plan.

3.2. Name the syntactic features of the text.

3.3. List the means of connecting parts of the text.

“Cell nucleus” - Cell size. Lysosomes. Mitosis. Problematic question. Nuclear envelope. Thick murein shell (peptidoglycan layer). Set of chromosomes and cell division. In mesosomes or cytoplasmic membranes (anaerobic, aerobic), some are capable of nitrogen fixation. Organoids. Eukaryotic cell. Type of food.

“Structure of the core” - Perhaps the densest in terrestrial conditions. If there are about 100 elements in nature, then there are more than 2000 isotopes. The nucleus of an atom consists of nucleons, which are divided into protons and neutrons. The negative charge of all electrons is distributed throughout the entire volume of the atom. Protons and neutrons in the nucleus are usually called nucleons.

“Body cell” - Prokaryotes and eukaryotes. EPS is formed by the simplest membrane. Prokaryotes. V.A.Engelgurd. 3 Comparison of plant and animal cells. Empire Life. Problematic question. Kingdom of Bacteria. Superkingdom Prenuclear organisms. Prokaryotic cell. Kingdom of Plants. Animal Kingdom. Kingdom of Mushrooms. Cell evolution.

“Nuclear biology” - Transfer of information from the mother cell to the daughter cells. (Sex cells). Diploid set of chromosomes. Functions of chromosomes. In 1831 he discovered the nucleus in the cell sap - the most important component of the cell. The core of the sun. (Lack of core). Domestic dog. Biology lesson. Cell nucleus. Viruses (precellular life forms). Inner membrane.

“Cells of living organisms” - Non-cellular organisms include viruses, united in the kingdom Viruses. Many organisms cool themselves by evaporating water (transpiration in plants, sweating in animals). The acidity or basicity of a solution is determined by the concentration of H+ ions in it. The water molecule is polarized and is a dipole (has two poles).

“Atomic nuclei” - N? Z diagram of atomic nuclei. Nuclear fission. Superheavy nuclei (A > 100). Diagram of a nuclear power plant. Scattering of a particle in the Coulomb field of a nucleus. Mass and binding energy of the nucleus. Models of atomic nuclei. Radioactivity. Composition of the atomic nucleus. Rutherford's experience. Nuclear forces. The magnetic field is created by superconducting windings.

Question 1. What are the functions of the cell nucleus?
The nucleus in a cell performs the main functions:
1. storage and reproduction of hereditary information, which is stored in the nucleus in the form of DNA molecules that make up the chromosomes;
2. regulation of metabolism in the cell is carried out due to the fact that the nucleus contains hereditary information about the structure of cellular proteins as part of nuclear chromosomes.

Question 2. What organisms are prokaryotes?
Prokaryotes- these are organisms whose cells do not have a formed nucleus. These include bacteria, blue-green algae (cyanobacteria) and archaea.

Question 3. How is the nuclear membrane structured?
Nuclear envelope – separates the contents of the nucleus from the cytoplasm. The nuclear envelope consists of two membranes: outer and inner, which are joined together in the pore region. With an increase in the rate of metabolic processes between the nucleus and the cytoplasm, the number of pores increases, i.e. one can judge the activity of the nucleus by the number of pores. The following come out of the nucleus through nuclear pores: mRNA, tRNA, ribosomal subunits. Nuclear and ribosomal proteins, nucleotides, fats, carbohydrates, ATP, water and ions enter the nucleus from the cytoplasm. The outer nuclear envelope is connected to the granular endoplasmic reticulum. The inner nuclear membrane is in contact with karyoplasm (nuclear juice), is devoid of ribosomes and in some places is connected to chromatin.

Question 4. What is chromatin?
Chromatin is a complex of DNA and proteins, mainly histones. Histone molecules with DNA form groups - nucleosomes. A DNA molecule connected to a nucleosome forms a DNP (deoxyribonucleoprotein), which is the smallest unit of a chromosome. Chromatin consists of RNA, Ca2+ and Mg2+ ions, as well as the enzyme DNA polymerase, which is necessary for DNA replication. During nuclear division, chromatin spirals and becomes visible in a light microscope, i.e. Chromosomes begin to form (Greek chromo - color, soma - body.).

Question 5. What are the functions of the nucleoli?
Nucleoli- these are round, highly compacted areas of the nucleus not limited by a membrane. Their shape, size and quantity depend on the functional state of the nucleus. In a cell that performs the function of synthesizing a large amount of protein, there will be several nucleoli in the nucleus or they will be large and loose, i.e. The function of the nucleolus is the synthesis of rRNA and the assembly of small and large ribosomal subunits. The nucleolus contains: 80% protein, 10-15% RNA, a small amount of DNA and other chemical components. During prophase of cell division, ribosomal subunits enter the cytoplasm through nuclear pores, the DNA of the nucleolus is packaged onto chromosomes that have a secondary constriction or nucleolar organizer, and accordingly, the nucleolus as a structure disintegrates and becomes an invisible structure, so it is sometimes said that it “dissolves.”

Question 6. What does a chromosome consist of?
A chromosome is a DNA molecule connected to a special protein that makes it compact.

Question 7. Where are chromosomes located in bacteria?
Bacterial cells do not have a formed nucleus. The genetic apparatus of bacteria is represented by one circular DNA molecule (bacterial chromosome), which is attached in a certain place to the cell membrane and occupies a space in the cytoplasm called a nucleoid.

Question 8. What is a karyotype?
A karyotype is a specific set of chromosomes characteristic of a given type of organism. The karyotype is characterized not only by the number of chromosomes, but also by their size, shape, and centromere location.

Question 9. What is the name of the set of chromosomes in somatic cells?
As a rule, somatic cells contain a double set of chromosomes, which is called diploid.

Question 10. What is the set of chromosomes in gametes?
Gametes contain only one chromosome of each type, that is, they have a single set of chromosomes, which is called haploid.

Question 11. What is the haploid set of chromosomes in cancer cells if the diploid one is 118?
If the diploid set of chromosomes in cells is 118, then the haploid set will be two times less - 59 (118/2=59).

Question 12. Can a diploid set contain an odd number of chromosomes?
A diploid set of chromosomes may contain an odd number of chromosomes. There are organisms that have only one sex chromosome in their somatic cells. For example, in some insects (bugs, grasshoppers), females are homogametic (XX), and males have only one sex chromosome (XO).