Biology oge theory for each task. What a schoolchild needs to know to independently prepare for the OGE in biology

Methods of preparation for the OGE in biology

OGE in biology is one of the exams that a student can choose to take in 9th grade. This subject is usually chosen by those who later plan to continue their studies in medical universities and specialized classes.

Structure of the OGE in biology next:

The work consists of two parts and contains 32 tasks.

Part 1: 28 tasks (1–28) with a short answer, which is a number or a sequence of numbers, of which 22 tasks with the choice of one correct short answer, 2 tasks with the choice of three correct answers, 1 task for matching terms, concepts, processes, 1 a task on the sequence of events, 1 task on correlating the morphological characteristics of an organism or its individual organs with the proposed models according to a given algorithm, and 1 task on working with text that has gaps.

Part 2: four tasks (29–32) with a detailed answer and a fully recorded process of solving the task. One task is to answer questions after reading the text, the second is to test the ability to work with a table and draw certain conclusions from statistical data. The third task tests the ability to create a menu with a certain calorie content for athletes, tourists, and ordinary schoolchildren. The fourth task is a free answer question.

Exam durationrelatively short - only 180 minutes. There are no reference materials for the State Examination in Biology, which means you have no one to rely on except yourself.Correspondence of OGE scores in biology to school grades following:

• 0-12 points – 2;
• 13-25 points – 3;
• 26-36 points – 4;
• 37-46 points – 5;

The specificity of testing, including the OGE in biology, lies in the formulation of questions. That is, often, we must not only know the answer to a question, we must understand what exactly the test compiler wanted to ask.

How to prepare a student to successfully pass the exam? How to reach that peak when a student is confident in his abilities and goes to the OGE without fear? Where to start and how to organize preparation for exams? How to improve the quality of teaching and student performance during the final certification of graduates? These questions constantly arise before every teacher who works in graduate classes. Preparing for the OGE is very difficult and painstaking work for both the teacher and the students. Currently, the problem of preparing for the OGE is very relevant.

In a large amount of information, descriptions of methods, methods and techniques of preparation, I try to select the most rational ones and build my own system based on them. Each teacher, depending on specific conditions, uses his own methods, methods and techniques.

Students in the same class have different levels of preparation; it may depend on whether the student intends to continue studying and whether his studies will be related to biology. In addition, the student’s readiness for the exam includes not only the ability to complete the proposed tasks, but also the ability to choose tasks that can be solved, and the presence of self-control skills, the ability to properly manage the time allotted for the exam, the ability to adjust oneself psychologically, concentrate attention, and manage one’s emotions . All these aspects require the teacher to use different methods to prepare students for the exam. Successfully mastering the subject and passing the final certification is possible only with systematic studies and effective organization of the educational process throughout the course from grades 5 to 9.

But the main preparation begins in 9th grade, when children consciously choose a biology exam in a new form.

1. First, we study the regulatory documents that determine the content and structure of biology education, the basic requirements for the knowledge, skills and abilities of students, as well as familiarize students with the structure, content and evaluation criteria of the examination work. We determine the presence, what knowledge and skills are tested by KIM tasks in biology, study the specification, codifier, demo version of the OGE. I distribute the training material in this way:

September

October

November

December – general patterns, material from the first half of the year and solving thematic assignments.

January – biology as a science, plant biology and solving thematic tasks.

February – animal biology and solving thematic tasks.

March – human biology and solving thematic tasks.

April – general patterns and solution of thematic tasks.

May – repetition and solution of OGE variants from a variety of publications.

To solve tests, we use printed manuals for preparing for the OGE.

For self-preparation at home, I recommend sites with online tests.

The texts of diagnostic and training work developed by the Moscow Institute of Open Education and conducted through the STATGRAD system help me identify the real level of training.

In the process of repeating the sections “Plants. Bacteria. Mushrooms. Lichens" and "Animals" I focus on working with images of organisms and their individual parts. Students must learn to recognize the most typical representatives of the animal and plant world, determine their belonging to the type, department, class.

In the repetition system, the central place is occupied by the section “Man and his health”, since half of all tasks are questions that test knowledge of the structure, life activity and hygiene of man. The exam begins with reading and understanding the question; when preparing students for the exam, we learn to read the wording of the questions, pay attention to the depth of the problem statement, and the diagnostic functions of the task.

The next direction iswork in class. When organizing repetition, I plan lessons with mandatory repetition of the content of course sections completed in previous years. I also conduct various forms of current control using tasks similar to the OGE tasks. The main emphasis during testing is on identifying the following skills: to substantiate biological processes and phenomena, to prove the unity and development of the organic world; compare the heredity and variability of organisms; determine the norms of a healthy lifestyle and human behavior in nature; calculate the consequences of global changes in the biosphere; establish relationships between structure and function at the level of cells, tissues, systems, the whole organism and the ecosystem; find cause-and-effect relationships in nature; formulate conclusions based on the knowledge gained in biology lessons. In my lessons, I use new information technologies, which allows me to diversify and combine the means of pedagogical influence on students, strengthen learning motivation and improve the assimilation of new material, makes it possible to qualitatively change self-control and control over learning outcomes, as well as better prepare for the OGE

The use of information technology in preparation for the Unified State Exam has many advantages: the combination of sound, image and interactivity allows graduates to achieve the best perception, assimilation and retention of material, the feedback system allows for prompt monitoring and assessment of knowledge.

Preparing students for exams with the help of ICT can be carried out both as part of a school lesson and in extracurricular activities (through elective courses, electives, individual lessons and consultations), as well as through distance learning, using ready-made electronic products, creating multimedia presentations, using resources Internet networks. For more successful preparation, an elective course “On the way to the OGE in biology” is taught in 9th grade.

In biology lessons and during extracurricular hours I use such multimedia teaching aids as:

• “Biology 10-11 grade. Interactive course for schoolchildren",
• "1C: School. Biology. Taking the Unified State Exam 2010",
• “Biology grades 6-11. Interactive teaching materials"
• “Biology lessons 10th grade. Electronic interactive application", "1C: School. Biology. Animals. 7th grade",
• "1C: School. Biology. Human. 8th grade",
• "1C: School. Fundamentals of general biology. 9th grade,” atlases on botany, zoology, anatomy, etc.

These programs can be used in conjunction with any printed textbook. They implement features that are missing in a printed textbook; these include thousands of bright illustrations, photographs, 3D models, and videos.

Their use makes it possible to solve the following didactic tasks:

Acquire basic and advanced knowledge of the subject,

Systematize acquired knowledge,

Psychologically prepare students for the exam atmosphere,

Provide a convenient educational environment and opportunities for independent choice in searching and using information sources,

In exam preparation classes, I first conduct a brief overview of the material being studied, then watch presentations, videos, materials from electronic manuals and other visual materials.

At the final stage of preparation for the final certification, training exercises become important and significant. I pay a lot of attention to solving test tasks. To do this, I use tasks from the open bank of Unified State Exam (USE) tasks in biology, posted on the FIPI websitehttp://www.fipi.ru/ and on the educational portal for exam preparationhttp://bio.reshuege.ru/ . I also use electronic simulators, tests for solving problems in the first part and presentations for solving problems in the second part.

To carry out training and diagnostic work, I use tasks from the StatGrad system -http://statgrad.mioo.ru/

On various information support sites for the Unified State Exam (http://bio.reshuege.ru/,http://egeigia.ru/ , http://ege.yandex.ru ) On-line trial testing options are offered. After school hours, students can go to the website and take part in this test.

• The next direction in the process of preparing students is systematic work directly with test tasks. First of all, I practice and consolidate basic level knowledge and skills. For these purposes I use tests and materials recommended by FIPI.

Test control attracts me because it is a quick check of the quality of learning, immediate correction of errors, a high degree of objectivity of the results obtained, and filling in gaps. Thus, this allows the teacher to quickly test students’ knowledge and process the information received without wasting time and effort. Another advantage of tests compared to other forms of control is that all students are on an equal footing, allowing their achievements to be objectively compared; teacher subjectivity is excluded; testing results are amenable to statistical processing. The use of test tasks allows the teacher to determine how students master knowledge, skills, and abilities, as well as to analyze their teaching activities. Students will be able to learn about their achievements or gaps in learning, compare their results with the standard, thereby developing self-control in students.

I speak at parent meetings in the 9th grade in order to inform parents about the procedure for conducting final certification, about the results of testing of students in the class, conducting explanatory work to provide psychological assistance to students and creating a favorable home environment during the preparation and conduct of the OGE, etc.

Thus, future graduates can experience the peculiarities of the OGE, tune in to the desired wavelength and successfully pass the exam on their own.

A modern ninth-grader treats the state final certification as a serious life test. Therefore, a final-grade teacher has a special responsibility: on the one hand, it is necessary to organize high-quality preparation for the upcoming exam, and on the other hand, not to lose the personal, creative, meaning of the subject being taught.

Thus, the effectiveness of passing the OGE is largely determined by how effectively the preparation process is organized at all levels of education, with all categories of students. And if we are able to instill in students independence, responsibility and readiness to continue learning throughout their entire lives, then we will not only fulfill the order of the state and society, but also increase our own self-esteem.

“The one who walks will master the road.”

Yulia Tsvetova:

THIS WILL HAPPEN SOONER OR LATER

I was reluctant to prepare for biology. I took it without tutors, because in the year when I wrote the OGE, the grade for the optional exam was not included in the certificate. I studied every day, Gushchina decided, I read a lot of literature, but, of course, I didn’t remember everything. I worked more on the second part. At first it was not very scary, I was practically not worried at all until the exams themselves began. I was scared by this whole atmosphere and the fact that something could go wrong.

The exam itself was quite stressful, because in the instructions for the OGE in biology it was written that we could have calculators with us, but everything was taken away from us at the entrance. Then panic began. I told the teacher who led me into the classroom that we had no right to take away the calculator. Then they finally returned him.

The exam itself turned out to be difficult. If you don't know biology, or think that it is an easy subject that you can pass by luck, then it is not so.

The teachers looked at us all the time, there were many inspectors in the corridors who escorted us to the toilet. I was more afraid not of the exam itself, but of its results later, but it turned out that not everything was so bad.
I told myself: “Time is still ticking, this will happen sooner or later.” You need to face your fears, and also drink Glycine.

Alexey Burmin:

YOU NEED TO STUDY ALL YEAR

It all started with the fact that the school year did not promise anything new except preparation for the exam. Everything went as usual. We learned a lot of new things and repeated even more old ones. I got bored with the gradual preparation for exams, and I decided to just sit in biology lessons, not write anything down, but listen to the smart speeches of the teacher, which I liked.

I didn't think it would help me pass my exams because I was overconfident and thought I knew everything. Having written a trial exam with an unsatisfactory grade, I decided that I should look through the textbook and notebooks a little, but soon I somehow abandoned this matter. The day before the exam, I didn't feel nervous at all. I thought that the exam was like an Olympiad, where I often attended, but with more difficult tasks and strict control.

The day of the exam has arrived. We entered the classroom and I, completely unprepared, began to write. All the questions were very familiar. On the one hand, I did not regret that I did not prepare for the OGE, because I had free time. On the other hand, I felt a little sad because I could have written for more points.

In the end, I want to say that whether to prepare for the exam or not is everyone’s decision. I can only advise you to study all year.

Natalya Vinogradova:

BIOLOGY IS CRAMMING

I can say that the OGE in biology is cramming. I took more than 150 tests while preparing for the exam, and used a group on a social network. Never rely on luck - study all topics. I didn’t study the material very deeply, and it was on this topic that I came across four questions.

Don't take a sedative - it will only make the situation worse. Don’t worry, but you definitely need to write cheat sheets. There is no need to take them with you - this is just to remember the information.

Naturally, like other students, I was worried, afraid, and thought that I wouldn’t pass, but when I saw the assignments, I realized that I was preparing for the worst.
The exam may be different for everyone. For example, we were let out one at a time to the toilet, and one boy left for 40 minutes. When they found him, he said that he was not feeling well, and he was given 30 minutes more time to write the OGE. We left water in the corridor.

In fact, it’s okay, but I, for example, advise you to think only about yourself at this moment and no one else.

The OGE in biology is not included in the list of mandatory exams, but is chosen by students quite often. According to experts, the majority of subjects pass the exam in this subject quite successfully, so the subject has gained the reputation of being relatively easy. Also, a number of 9th grade graduates plan to enter medical schools. Biology is also chosen when entering the 10th grade with a certain bias.At the 9th grade stage, there is not much material covered; it is quite easy to understand and master.

In 2018, the minimum threshold was 13 points - in other words, to pass the exam for the minimum score, you need to complete 13 tasks. Maximum – 32 points for an “excellent” rating.
The structure of the biology exam is similar to other exams:

• The first part is designed to test the level of knowledge of factual data, laws, and terms. These are ordinary test tasks where you need to find the correct answer from those proposed, establish correspondence, sequence - the answers are displayed in the answer form.
• The second part consists of several tasks that require a detailed answer. It is necessary to solve the problem and describe in detail the course of conclusions.
  

The first step is to decide on the goal that needs to be achieved. Based on the goal, you can create a detailed preparation plan. Without a plan, the process of repeating and studying information will be fragmentary, unsystematic, and the result will not be the best. Familiarization with will allow you to create a plan according to which preparation will be carried out. It is very important to organize yourself so that you do not deviate from the plan, and to study regularly. The best thing is to combine independent work, attentiveness in class and consultations with a teacher or tutor.
Solving the OGE in biology is an additional opportunity to assess the level of knowledge, consolidate theory, and get used to working with test tasks of different types and levels of complexity.
Is it possible to prepare from scratch?
Yes. This requires time, self-discipline and the opportunity to consult with a professional. In this case, it is recommended to hire a tutor and regularly complete assignments online.
It is recommended to begin preparation at the beginning of the 9th grade in order to repeat the material from previous years:

• General biology;
• Anatomy;
• Botany;
• Ecology;
• Zoology.
  

From work experience. System of preparation for the OGE in biology.

Biology teacher, Municipal Budgetary Educational Institution Secondary School No. 4, Lipetsk Manaenkova Z.A.

What is OGE?

• Main State Exam (OGE) – This is the main type of exam for 9th grade graduates in Russian secondary schools. Passing the OGE is required to move to grade 10 or enter the institutions of secondary vocational education(colleges and technical schools). Graduates of 9 classes of general education institutions take 2 required exams(Russian language and mathematics) and 2 exams in elective subjects. According to the new The procedure for conducting state final certification for educational programs of basic general education, students take exams in other academic subjects on a voluntary basis of their choice.

OGE tasks.

• Obtain objective information about students' educational achievements.
• To identify the level of students’ mastery of the content of biological education provided for by the 2004 standard.
• Determine the directions for improving the educational process in biology and the educational and methodological training of the course, outline ways to improve biological education at school, and increase the biological literacy of students.

Teaching biology today:

• Development of cognitive activity of students with all types of educational information, expansion of practice in solving cognitive problems, implementation of a problem-based approach to the study of biology.

Where to start and when to start preparing for the OGE?

• To successfully prepare students for the OGE, the teacher needs to collect and study information material on organizing and conducting preparation of students for the OGE. These can be methodological recommendations, manuals, simulators, electronic disks, Internet resources, etc.

Create a folder of documents for the OGE:

• Section I – FIPI materials. Website www.fipi.ru
• Section II – information material for the OGE.
• Section III – test and measurement material on biology.
• Section IV – tips for passing the OGE.

Section I – FIPI materials

• Specification of testing and measuring materials for the 2017 OGE in biology.
• Codifier of content elements and requirements for the level of training of graduates of general education institutions for the 2017 OGE in biology.

• Demonstration version of control and measurement materials for the 2017 OGE in biology.
• OGE forms.
• Analysis of the results of the exam paper in biology for 2016.

Section II – information material for the OGE

• What is OGE?
• The procedure for conducting the OGE.
• Various teaching aids.

Section III – test and measurement material in biology

• Test and measurement material for biology grade 6.
• Test and measurement material for biology grade 7.
• Test and measurement material for biology grade 8.
• Test and measurement material for biology grade 9.

Section IV - tips for passing the OGE

• Rules for filling out forms.
• Psychological advice to graduates taking the OGE.
• Psychological recommendations to parents of graduates when preparing for the OGE.
• Advice to graduates on how to act when passing the OGE.
• Exam preparation.

Internet resources.

• Federal Institute of Pedagogical measurements http://www.fipi.ru/
• Federal Center testing http://www.rustest.ru/

• Work includes 32 tasks and consists of two parts.
• Part 1 contains 28 tasks with a short answer:
• 22 tasks basic level of difficulty with the answer in the form of one digit corresponding to the number of the correct answer;
• 6 tasks increased difficulty level:
• 2 tasks with choosing and recording three correct answers out of six, 3 tasks to establish the correspondence of elements of two information series (including the task of including terms and concepts missed in the text, of correlating the morphological characteristics of an organism or its individual organs with the proposed models according to a given algorithm),
• 1 task to determine the sequence of biological processes, phenomena, objects.

The main types of tasks offered at the OGE in biology.

• Part 2 contains 4 tasks with a detailed answer:
• 1 increased level of complexity for working with text, involving the use of information from the text of contextual knowledge to answer the questions posed;
• the rest are of a high level of complexity:
• 1 to analyze statistical data presented in tabular form,
• 2 on the application of biological knowledge to solve practical problems.
• Maximum Primary Score for completing all the work - 46 .

• The OGE examination paper includes five content blocks that correspond to the blocks of the Federal component of the state standard of basic general education in biology.

• First block "Biology as a Science" includes tasks that control knowledge: about the role of biology in the formation of the modern natural science picture of the world, in the practical activities of people; methods of studying living objects (observation, description, measurement, experiment).

• Second block "Signs of living organisms" is presented with tasks that test knowledge: about the structure, functions and diversity of cells, tissues, organs and organ systems; signs of living organisms, heredity and variability; methods of reproduction, methods of growing plants and breeding animals.

• Third block "System, diversity and evolution of living nature" contains tasks that control knowledge: about the most important distinctive features of the main kingdoms of living nature (Animals, Plants, Fungi, Bacteria); classification of plants and animals (division (type), class); about the complication of plants and animals in the process of evolution; about biodiversity as the basis for the stability of the biosphere and the result of evolution.

• Fourth block "Man and his health" contains tasks that reveal knowledge: about the origin of man and his biosocial nature, higher nervous activity and the characteristics of human behavior; the structure and vital functions of organs and organ systems (nervous, endocrine, circulatory, lymphatic, respiration, excretion, digestion, reproductive, support and movement); internal environment, immunity, sensory organs, neurohumoral regulation of vital processes.

• Fifth block "Interrelations between organisms and the environment" contains tasks that test knowledge: about the systemic organization of living nature, about environmental factors, about the interaction of different species in nature; about natural and artificial ecosystems and their components, food connections; about environmental problems, their impact on their own lives and the lives of other people; about the rules of behavior in the environment and ways to maintain balance in it.

• https:// vk.com/public135643854

9A 12/12/2016

Results of rehearsal testing in biology in 9B 12/12/2016

Test results

Ratings

Class

Academic performance

Quality of knowledge

Average score

Cell structure, cell division, protein biosynthesis. Reproduction. Development -

Ontogenesis

Properties of living structures:

1) self-renewal. Metabolism is based on the interconnected processes of assimilation (anabolism, synthesis, formation of new substances) and dissimilation (catabolism, decay);

2) self-reproduction. Nucleic acids are capable of storing, transmitting and reproducing hereditary information, as well as implementing it through protein synthesis. The information stored on DNA is transferred to the protein molecule using RNA molecules;

3) self-regulation. Based on the totality of flows of matter, energy and information through a living organism;

4) irritability. Associated with the transfer of information from the outside to any biological system and reflects the reaction of this system to an external stimulus

5) maintaining homeostasis - the relative dynamic constancy of the internal environment of the body

7) adaptation - the ability of a living organism to constantly adapt to changing conditions of existence in the environment;

8) reproduction (reproduction

9) heredity. Thanks to heredity, traits that ensure adaptation to the environment are passed on from generation to generation;

10) variability - due to variability, a living system acquires characteristics that were previously unusual for it

11) individual development (ontogenesis process). During this process, such a property as the ability to grow appears, which is expressed in an increase in body weight and its size;

12) phylogenetic development. Based on progressive reproduction, heredity, struggle for existence and selection. As a result of evolution, a huge number of species appeared;

13) discreteness (discontinuity) and at the same time integrity. Each organism, in turn, is also discrete, since it consists of a collection of organs, tissues and cells.

Squirrels are polymers whose monomers are amino acids Functions of proteins: 1) protective; 2) structural; 3) motor; 4) storage; 5) transport; 6) receptor; 7) regulatory; 8) hormone proteins participate in humoral regulation; 9) enzyme proteins catalyze all chemical reactions in the body; 10) energy.

Carbohydrates - these are mono- and polymers, which include carbon, hydrogen and oxygen. Functions of carbohydrates: 1) energy; 2) structural; 3) storage.

Fats (lipids) can be simple or complex. Simple lipid molecules consist of the trihydric alcohol glycerol and three fatty acid residues. Complex lipids are compounds of simple lipids with proteins and carbohydrates. Functions of lipids: 1) energy; 2) structural; 3) storage; 4) protective; 5) regulatory; 6) heat insulating.

The ATP (adenosine triphosphoric acid) molecule is formed in mitochondria and is the main source of energy.

5. Protein biosynthesis. Genetic code

There are 2 types of nucleic acids - deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

DNA is a helix consisting of two complementary polynucleotide chains twisted to the right. Two chains of nucleotides are connected to each other through nitrogenous bases according to the principle of complementarity: two hydrogen bonds arise between adenine and thymine, and three between guanine and cytosine.

Functions of DNA:

1) ensures the preservation and transmission of genetic information from cell to cell and from organism to organism (replication);

2) regulates all processes in the cell, providing the ability for transcription followed by translation.

Replication occurs during the synthetic period of interphase of mitosis. The replicase enzyme moves between the two strands of the DNA helix and breaks hydrogen bonds between nitrogenous bases. Then, using the enzyme DNA polymerase, the nucleotides of the daughter chains are added to each of the chains according to the principle of complementarity. As a result of replication, two identical DNA molecules are formed. The amount of DNA in the cell doubles. This method of DNA doubling is called semi-conservative, since each new DNA molecule contains one “old” and one newly synthesized polynucleotide chain.

RNA is a single-stranded polymer. There are 3 types of RNA.

1. Messenger RNA (i-RNA) is located in the nucleus and cytoplasm of the cell and performs the function of transferring hereditary information from the nucleus to the cytoplasm of the cell.

2. Transfer RNA (tRNA) is also found in the nucleus and cytoplasm of the cell and delivers amino acids to ribosomes during the process of translation - protein biosynthesis.

3. Ribosomal RNA (r-RNA) is found in the nucleolus and ribosomes of the cell.

Protein biosynthesis occurs in several stages.

1. Transcription is the process of synthesis of mRNA on a DNA template.

2. Then processing occurs - maturation of the RNA molecule.

Transcription occurs in the cell nucleus. Then the mature mRNA enters the cytoplasm through pores in the nuclear membrane, and translation begins.

3. Translation is the process of protein synthesis on a matrix and RNA.

Genetic code It is a system of encoding the amino acid sequence of a protein as a specific sequence of nucleotides in DNA and RNA.

A unit of genetic code (codon) is a triplet of nucleotides in DNA or RNA that codes for one amino acid.

In total, the genetic code includes 64 codons, of which 61 are coding and 3 are non-coding (terminator codons).

Terminator codons in mRNA: UAA, UAG, UGA, in DNA: ATT, ATC, ACT.

The genetic code has characteristic properties.

1. Universality - the code is the same for all organisms.

2. Specificity - each codon encodes only one amino acid.

Prenuclear prokaryotes do not have a typical nucleus. These include bacteria and blue-green algae.

Prokaryotes arose in the Archean era. These are very small cells ranging in size from 0.1 to 10 microns.

A typical bacterial cell is surrounded on the outside by a cell wall, the basis of which is the substance murein and determines the shape of the bacterial cell. On top of the cell wall there is a mucous capsule that performs a protective function.

Below the cell wall is the plasma membrane. The entire cell inside is filled with cytoplasm, which consists of a liquid part (hyaloplasm, or matrix), organelles and inclusions.

Hereditary apparatus: one large “naked” DNA molecule, devoid of protective proteins, closed in a ring - a nucleoid. The hyaloplasm of some bacteria also contains short circular DNA molecules that are not associated with a chromosome or nucleoid - plasmids.

There are few membrane organelles in prokaryotic cells. There are mesosomes - internal outgrowths of the plasma membrane, which are considered the functional equivalent of eukaryotic mitochondria. In autotrophic prokaryotes, lamellae and lamesomes are found - photosynthetic membranes. They contain the pigments chlorophyll and phycocyanin.

Some bacteria have organelles of movement - flagella. Bacteria have recognition organelles called pili (fimbriae).

Chromatin in the form of clumps is scattered in the nucleoplasm and is an interphase form of chromosome existence.

Plant cells also contain chloroplasts, in which photosynthesis occurs.

Functions and structure of the cytoplasmic membrane and cell nucleus

The elementary membrane consists of a bilayer of lipids in complex with proteins. Each fat molecule has a polar hydrophilic head and a non-polar hydrophobic tail. In this case, the molecules are oriented so that the heads face outward and inside the cell, and the non-polar tails face inside the membrane itself. This achieves selective permeability for substances entering the cell.

Functions of membrane proteins: receptor, structural, enzymatic, transport

1) barrier (delimitation of the internal contents of the cell);

2) structural (giving a certain shape to cells);

3) protective (due to selective permeability);

4) regulatory (regulation of selective permeability for various substances);

5) adhesive function (all cells are connected to each other through specific contacts (tight and loose);

6) receptor;

The cell nucleus consists of a membrane, nuclear sap, nucleolus and chromatin . Nuclear envelope consists of two membranes. The main functions of the nuclear membrane: separation of genetic material (chromosomes) from the cytoplasm, as well as regulation of bilateral relationships between the nucleus and the cytoplasm.

The nuclear envelope is permeated with pores, which have a diameter of about 90 nm.

The basis of nuclear juice (matrix, nucleoplasm) is proteins. The juice forms the internal environment of the nucleus and plays an important role in the functioning of the genetic material of cells.

Nucleolus is the structure where the formation and maturation of ribosomal RNA (rRNA) occurs. rRNA genes occupy certain regions of several chromosomes, where nucleolar organizers are formed, in the area of ​​which the nucleoli themselves are formed.

Chromatin consists mainly of DNA strands (40% of the chromosome mass) and proteins (about 60%), which together form a nucleoprotein complex.

8. Structure and functions of mitochondria and lysosomes

Mitochondria- these are permanent membrane organelles of a round or rod-shaped (often branching) shape. Main functions of mitochondria:

1) play the role of energy stations of cells;

2) store hereditary material in the form of mitochondrial DNA.

Mitochondria have two membranes: outer (smooth) and inner (forming outgrowths - leaf-shaped (cristae) and tubular (tubules)).

Lysosomes- these are bubbles with a diameter of 200-400 microns. (usually). They have a single membrane shell. The main function is intracellular digestion of various chemical compounds and cellular structures.

Endoplasmic reticulum (ER)- a system of communicating or separate tubular channels and flattened cisterns located throughout the cytoplasm of the cell. ER channels can connect to the surface or nuclear membranes and contact the Golgi complex. Rough XPS Ribosomes are located on the channels of the rough ER in the form of polysomes. Protein synthesis occurs here Smooth XPS There are no ribosomes on the smooth ER membranes. The synthesis of fats and similar substances (for example, steroid hormones), as well as carbohydrates, takes place here. The channels of the smooth ER also transport the finished material to the place of its packaging into granules (to the area of ​​the Golgi complex). Golgi complex gives rise to primary lysosomes.

10. Structure and functions of non-membrane cell structures

Ribosome It is a round ribonucleoprotein particle. Its diameter is 20-30 nm. The ribosome consists of large and small subunits. The cells of all animals, some fungi, algae, and higher plants are characterized by the presence of a cellular center. Cell center usually located next to the nucleus. It consists of two centrioles, located mutually perpendicular. From the centrioles of the cell center, during cell division, filaments of the spindle are formed. Centrioles polarize the process of cell division, thereby achieving uniform separation of sister chromosomes (chromatids) in anaphase of mitosis. Inside the cell is cytoplasm. It consists of a liquid part - hyaloplasm (matrix), organelles and cytoplasmic inclusions. Hyaloplasma- the main substance of the cytoplasm. Inclusions are relatively unstable components of the cytoplasm. There are: 1) reserve nutrients that are used by the cell itself during periods of insufficient supply of nutrients from the outside; 2) products that must be released from the cell;

Many viruses are the causative agents of diseases such as AIDS, rubella measles, mumps, chickenpox and smallpox. Mature virus particles are called virions. In fact, they are a genome covered with a protein shell on top. This shell is the capsid.

Gametes Egg- a large, immobile cell with a supply of nutrients. The size of a female egg is 150-170 microns Sperm is a male reproductive cell (gamete). He has the ability to move. The dimensions of the sperm are microscopic: the length of this cell in humans is 50-70 microns

The sperm has a head, a neck, an intermediate section and a tail in the form of a flagellum. Almost the entire head is filled with a nucleus, which carries hereditary material in the form of chromatin. At the anterior end of the head (at its apex) there is an acrosome, which is a modified Golgi complex.

Fertilization- This is the process of fusion of germ cells. As a result of fertilization, a diploid cell is formed - a zygote. The biological role of asexual reproduction Maintenance of fitness reinforces the importance of stabilizing natural selection; ensures rapid reproduction rates; used in practical selection. Forms of asexual reproduction

In unicellular organisms, the following forms of asexual reproduction are distinguished: division, endogony, schizogony and budding, sporulation.

Division characteristic of amoeba, ciliates, flagellates. First, mitotic division of the nucleus occurs, then the cytoplasm is divided in half by an increasingly deepening constriction. In this case, daughter cells receive approximately the same amount of cytoplasm and organelles.

Endogony(internal budding) is characteristic of toxoplasma. When two daughters are formed, the mother gives only two offspring. But there may be internal multiple budding, which will lead to schizogony.

It is found in sporozoans (malarial plasmodium), etc. Multiple divisions of the nucleus occur without cytokinesis. From one cell many daughter cells are formed.

Budding(in bacteria, yeasts, etc.).

Sporulation(in higher spore plants: mosses, ferns, mosses, horsetails, algae).. Vegetative a form of reproduction by part of the mother's body.

regeneration- restoration of lost tissues and body parts (in annelids, lizards, salamanders). Sexual reproduction - fertilization, Parthenogenesis - daughter organisms develop from unfertilized eggs. The meaning of parthenogenesis:

1) reproduction is possible with rare contacts of opposite-sex individuals; 2) the population size increases sharply; 3) occurs in populations with high mortality during one season.

Cell division. Mitosis phases:

1) prophase. The centrioles of the cell center divide and move to opposite poles of the cell. A fission spindle is formed from microtubules, which connects the centrioles of different poles. At the beginning of prophase, the nucleus and nucleoli are still visible in the cell; by the end of this phase, the nuclear envelope is divided into separate fragments. Chromosomes begin to condense: they curl, thicken, and become visible under a light microscope. In the cytoplasm, the number of rough ER structures decreases, the number of polysomes sharply decreases;

2) metaphase. The formation of the fission spindle ends. Condensed chromosomes line up along the equator of the cell, forming a metaphase plate. Spindle microtubules are attached to the centromeres, or kinetochores (primary constrictions), of each chromosome. After this, each chromosome is longitudinally split into two chromatids (daughter chromosomes), which are connected only at the centromere;

3) anaphase. The connection between the daughter chromosomes is broken, and they begin to move to opposite poles of the cell. At the end of anaphase, each pole has a diploid set of chromosomes. Chromosomes begin to decondense and unwind, becoming thinner and longer;

4) telophase. Chromosomes are completely despiralized, the structure of the nucleoli and interphase nucleus is restored, and the nuclear membrane is assembled. The fission spindle is destroyed. Cytokinesis (cytoplasm division) occurs. The formation of a constriction begins in the equatorial plane, which completely divides the mother cell into two daughter cells.

1. Amitosis- This is direct fission of the nucleus. At the same time, the morphology of the nucleus is preserved, the nucleolus and nuclear membrane are visible. The chromosomes are not visible and are not evenly distributed. The nucleus is divided into two relatively equal parts without the formation of a mitotic apparatus. Meiosis is a type of cell division in which the number of chromosomes is halved and Stages of meiosis The first division of meiosis (reduction) leads to the formation of haploid cells from diploid cells. In prophase I, as in mitosis, chromosome spiralization occurs. At the same time, homologous chromosomes come together with their identical sections (conjugate), forming bivalents. Before entering meiosis, each chromosome has doubled genetic material and consists of two chromatids, so the bivalent contains 4 strands of DNA. In the process of further spiralization, crossing over can occur - the crossing of homologous chromosomes, accompanied by the exchange of corresponding sections between their chromatids. In metaphase I, the formation of the division spindle is completed, the threads of which are attached to the centromeres of chromosomes, united into bivalents in such a way that only one thread goes from each centromere to one of the poles of the cell. In anaphase I, the chromosomes diverge to the poles of the cell, with each pole having a haploid set of chromosomes, consisting of two chromatids. In telophase I, the nuclear envelope is restored, after which the mother cell divides into two daughter cells.

The second division of meiosis begins immediately after the first and is similar to mitosis, but the cells entering it carry a haploid set of chromosomes. Prophase II is very short in time. This is followed by metaphase II, during which the chromosomes are located in the equatorial plane, and a spindle is formed. In anaphase II, centromeres separate and each chromatid becomes an independent chromosome. The daughter chromosomes separated from each other are directed to the division poles. In telo-phase II, cell division occurs, in which 4 daughter haploid cells are formed from two haploid cells.

Thus, as a result of meiosis, four cells with a haploid set of chromosomes are formed from one diploid cell. The biological significance of meiosis 1) is the main stage of gametogenesis; 2) ensures the transfer of genetic information from organism to organism during sexual reproduction; 3) daughter cells are not genetically identical to the mother and between themselves. Gametogenesis is the process of formation of germ cells. Ontogenesis- this is the process of individual development of an individual from the moment of formation of the zygote during sexual reproduction until the end of life. The first stage of embryonic development - splitting up. In this case, first 2 cells are formed from the zygote through mitotic division, then 4, 8, etc. The resulting cells are called blastomeres, and the embryo at this stage of development is called a blastula. At the same time, the total mass and volume almost do not increase, Gastrulation. At this time, blastomeres, which continue to rapidly divide, acquire motor activity and move relative to each other, forming layers of cells - germ layers from the ectoderm, skin and its derivatives develop. The endoderm gives rise to the organs of the respiratory and digestive systems. Muscle, cartilage and bone tissue, organs of the circulatory and excretory systems are formed from the mesoderm.

Dissimilation, or energetic exchange is a set of reactions of the breakdown of high-molecular compounds, which are accompanied by the release and storage of energy.
Stage 1 Preparatory:
occurs in lysosomes or in food. The system breaks down complex organic substances into simpler ones
(e.g. proteins to amino acids)
At this stage, ATP is not synthesized
Stage 2 Oxygen-free (glycolysis):
occurs in the cytoplasm
glucose to 2 molecules of pyruvic acid
energy reserve in the form of 2 ATP molecules

Stage 3 Oxygen:
occurs in mitochondria
oxidation of pyruvic acid to CO2 and H2O
36 mol ATP is formed