The biological significance of nk is the concept of the genetic code. Biosynthesis of protein and nucleic acids

The genetic code, which is also called the amino acid code, is a system for recording information about the sequence of amino acids in a protein using the sequence of nucleotide residues in DNA that contain one of the 4 nitrogenous bases: adenine (A), guanine (G), cytosine (C) and thymine (T). However, since the double-stranded DNA helix is ​​not directly involved in the synthesis of the protein that is encoded by one of these strands (i.e. RNA), the code is written in the language of RNA, in which uracil (U) is included instead of thymine. For the same reason, it is customary to say that a code is a sequence of nucleotides, not base pairs.

The genetic code is represented by certain code words - codons.

The first code word was deciphered by Nirenberg and Mattei in 1961. They obtained an extract from E. coli containing ribosomes and other factors necessary for protein synthesis. The result was a cell-free system for protein synthesis, which could assemble a protein from amino acids if the necessary mRNA was added to the medium. By adding synthetic RNA, consisting only of uracils, to the medium, they found that a protein was formed consisting only of phenylalanine (polyphenylalanine). So it was found that the triplet of UUU nucleotides (codon) corresponds to phenylalanine. Over the next 5-6 years, all codons of the genetic code were determined.

The genetic code is a kind of dictionary that translates a text written with four nucleotides into a protein text written with 20 amino acids. The rest of the amino acids found in the protein are modifications of one of the 20 amino acids.

Properties of the genetic code

The genetic code has the following properties.

1. Tripletity Each amino acid corresponds to a triple of nucleotides. It is easy to calculate that there are 4 3 = 64 codons. Of these, 61 are semantic and 3 are meaningless (terminating, stop codons).
2. Continuity(there are no separating characters between nucleotides) - the absence of intragenic punctuation marks;

   Within a gene, each nucleotide is part of a significant codon. In 1961 Seymour Benzer and Francis Crick experimentally proved the triplet code and its continuity (compactness) [show]

   

   The essence of the experiment: "+" mutation - the insertion of one nucleotide. "-" mutation - loss of one nucleotide.

   A single mutation ("+" or "-") at the beginning of a gene or a double mutation ("+" or "-") spoils the entire gene.

   A triple mutation ("+" or "-") at the beginning of a gene spoils only part of the gene.

   A quadruple "+" or "-" mutation again spoils the entire gene.

   The experiment was carried out on two adjacent phage genes and showed that

   1. the code is triplet and there are no punctuation marks inside the gene
   2. there are punctuation marks between genes
3. Presence of intergenic punctuation marks- the presence among the triplets of initiating codons (they begin protein biosynthesis), codons - terminators (indicate the end of protein biosynthesis);

   Conventionally, the AUG codon also belongs to punctuation marks - the first after the leader sequence. It performs the function of a capital letter. In this position, it codes for formylmethionine (in prokaryotes).

   At the end of each gene encoding a polypeptide, there is at least one of 3 termination codons, or stop signals: UAA, UAG, UGA. They terminate the broadcast.

4. Collinearity- correspondence of the linear sequence of mRNA codons and amino acids in the protein.
5. Specificity- each amino acid corresponds only to certain codons that cannot be used for another amino acid.
6. Unidirectional- codons are read in one direction - from the first nucleotide to the next
7. Degeneracy, or redundancy, - several triplets can encode one amino acid (amino acids - 20, possible triplets - 64, 61 of them are semantic, i.e., on average, each amino acid corresponds to about 3 codons); the exception is methionine (Met) and tryptophan (Trp).

   The reason for the degeneracy of the code is that the main semantic load is carried by the first two nucleotides in the triplet, and the third is not so important. From here code degeneracy rule : if two codons have two identical first nucleotides, and their third nucleotides belong to the same class (purine or pyrimidine), then they code for the same amino acid.

   However, from this ideal rule there are two exceptions. These are the AUA codon, which should correspond not to isoleucine, but to methionine, and the UGA codon, which is the terminator, while it should correspond to tryptophan. The degeneracy of the code obviously has an adaptive value.

8. Versatility- all the properties of the genetic code listed above are characteristic of all living organisms.

   codon	Universal code	Mitochondrial codes
   		Vertebrates	Invertebrates	Yeast	Plants
   UGA	STOP	trp	trp	trp	STOP
   AUA	ile	Met	Met	Met	ile
   CUA	Leu	Leu	Leu	Thr	Leu
   AGA	Arg	STOP	Ser	Arg	Arg
   AGG	Arg	STOP	Ser	Arg	Arg

   Recently, the principle of the universality of the code has been shaken in connection with the discovery by Berell in 1979 of the ideal code of human mitochondria, in which the code degeneracy rule is fulfilled. In the mitochondrial code, the UGA codon corresponds to tryptophan, and AUA to methionine, as required by the code degeneracy rule.

   Perhaps, at the beginning of evolution, all the simplest organisms had the same code as the mitochondria, and then it underwent slight deviations.

9. non-overlapping- each of the triplets of the genetic text is independent of each other, one nucleotide is part of only one triplet; On fig. shows the difference between overlapping and non-overlapping code.

   In 1976 φX174 phage DNA was sequenced. It has a single stranded circular DNA of 5375 nucleotides. The phage was known to encode 9 proteins. For 6 of them, genes located one after another were identified.

   It turned out that there is an overlap. The E gene is completely within the D gene. Its start codon appears as a result of a one nucleotide shift in the reading. The J gene starts where the D gene ends. The start codon of the J gene overlaps with the stop codon of the D gene by a two-nucleotide shift. The design is called "reading frame shift" by a number of nucleotides that is not a multiple of three. To date, overlap has only been shown for a few phages.

10. Noise immunity- the ratio of the number of conservative substitutions to the number of radical substitutions.

    Mutations of nucleotide substitutions that do not lead to a change in the class of the encoded amino acid are called conservative. Mutations of nucleotide substitutions that lead to a change in the class of the encoded amino acid are called radical.

    Since the same amino acid can be encoded by different triplets, some substitutions in triplets do not lead to a change in the encoded amino acid (for example, UUU -> UUC leaves phenylalanine). Some substitutions change the amino acid to another from the same class (non-polar, polar, basic, acidic), other substitutions also change the class of the amino acid.

    In each triplet, 9 single substitutions can be made, i.e. you can choose which of the positions to change - in three ways (1st or 2nd or 3rd), and the selected letter (nucleotide) can be changed to 4-1 \u003d 3 other letters (nucleotides). Total possible replacements nucleotides - 61 by 9 = 549.

    By direct counting on the table of the genetic code, one can verify that of these: 23 nucleotide substitutions lead to the appearance of codons - translation terminators. 134 substitutions do not change the encoded amino acid. 230 substitutions do not change the class of the encoded amino acid. 162 substitutions lead to a change in the amino acid class, i.e. are radical. Of the 183 substitutions of the 3rd nucleotide, 7 lead to the appearance of translation terminators, and 176 are conservative. Of the 183 substitutions of the 1st nucleotide, 9 lead to the appearance of terminators, 114 are conservative and 60 are radical. Of the 183 substitutions of the 2nd nucleotide, 7 lead to the appearance of terminators, 74 are conservative, and 102 are radical.

Every living organism has a special set of proteins. Certain compounds of nucleotides and their sequence in a DNA molecule form genetic code. It conveys information about the structure of the protein. In genetics, a certain concept has been adopted. According to her, one gene corresponded to one enzyme (polypeptide). It should be said that research on nucleic acids and proteins has been carried out for a fairly long period. Further in the article, we will take a closer look at the genetic code and its properties. A brief chronology of research will also be given.

Terminology

The genetic code is a way of encoding the amino acid protein sequence using the nucleotide sequence. This method of forming information is characteristic of all living organisms. Proteins - natural organic matter with high molecular weight. These compounds are also present in living organisms. They consist of 20 types of amino acids, which are called canonical. Amino acids are arranged in a chain and connected in a strictly established sequence. It determines the structure of the protein and its biological properties. There are also several chains of amino acids in the protein.

DNA and RNA

Deoxyribonucleic acid is a macromolecule. She is responsible for the transmission, storage and implementation of hereditary information. DNA uses four nitrogenous bases. These include adenine, guanine, cytosine, thymine. RNA consists of the same nucleotides, except for the one that contains thymine. Instead, a nucleotide containing uracil (U) is present. RNA and DNA molecules are nucleotide chains. Thanks to this structure, sequences are formed - the "genetic alphabet".

Implementation of information

The synthesis of a protein encoded by a gene is realized by combining mRNA on a DNA template (transcription). There is also a transfer of the genetic code into a sequence of amino acids. That is, the synthesis of the polypeptide chain on mRNA takes place. To encode all amino acids and signal the end of the protein sequence, 3 nucleotides are enough. This chain is called a triplet.

Research history

The study of protein and nucleic acids was carried out long time. In the middle of the 20th century, the first ideas about the nature of the genetic code finally appeared. In 1953, it was found that some proteins are made up of sequences of amino acids. True, at that time they could not yet determine their exact number, and there were numerous disputes about this. In 1953, Watson and Crick published two papers. The first declared the secondary structure of DNA, the second spoke of its admissible copying by means of matrix synthesis. In addition, emphasis was placed on the fact that a particular sequence of bases is a code that carries hereditary information. American and Soviet physicist Georgy Gamov admitted the coding hypothesis and found a method to test it. In 1954, his work was published, during which he put forward a proposal to establish correspondences between amino acid side chains and diamond-shaped "holes" and use this as a coding mechanism. Then it was called rhombic. Explaining his work, Gamow admitted that the genetic code could be triplet. The work of a physicist was one of the first among those that were considered close to the truth.

Classification

After several years, various models of genetic codes were proposed, representing two types: overlapping and non-overlapping. The first one was based on the occurrence of one nucleotide in the composition of several codons. The triangular, sequential and major-minor genetic code belongs to it. The second model assumes two types. Non-overlapping include combinational and "code without commas". The first variant is based on the encoding of an amino acid by nucleotide triplets, and its composition is the main one. According to the "no comma code", certain triplets correspond to amino acids, while the rest do not. In this case, it was believed that if any significant triplets were arranged sequentially, others located in a different reading frame would turn out to be unnecessary. Scientists believed that it was possible to select a nucleotide sequence that would meet these requirements, and that there were exactly 20 triplets.

Although Gamow et al questioned this model, it was considered the most correct over the next five years. At the beginning of the second half of the 20th century, new data appeared that made it possible to detect some shortcomings in the "code without commas". Codons have been found to be able to induce protein synthesis in vitro. Closer to 1965, they comprehended the principle of all 64 triplets. As a result, redundancy of some codons was found. In other words, the sequence of amino acids is encoded by several triplets.

Distinctive features

The properties of the genetic code include:

Variations

For the first time, the deviation of the genetic code from the standard was discovered in 1979 during the study of mitochondrial genes in the human body. Further similar variants were identified, including many alternative mitochondrial codes. These include the deciphering of the stop codon UGA used as the definition of tryptophan in mycoplasmas. GUG and UUG in archaea and bacteria are often used as starting variants. Sometimes genes code for a protein from a start codon that differs from the one normally used by that species. Also, in some proteins, selenocysteine ​​and pyrrolysine, which are non-standard amino acids, are inserted by the ribosome. She reads the stop codon. It depends on the sequences found in the mRNA. Currently, selenocysteine ​​is considered the 21st, pyrrolizan - the 22nd amino acid present in proteins.

General features of the genetic code

However, all exceptions are rare. In living organisms, in general, the genetic code has a number of common features. These include the composition of the codon, which includes three nucleotides (the first two belong to the determining ones), the transfer of codons by tRNA and ribosomes into an amino acid sequence.

Under the genetic code, it is customary to understand such a system of signs denoting the sequential arrangement of nucleotide compounds in DNA and RNA, which corresponds to another sign system, representing the sequence of amino acid compounds in a protein molecule.

It is important!

When scientists managed to study the properties of the genetic code, universality was recognized as one of the main ones. Yes, strange as it may sound, everything is united by one, universal, common genetic code. It was formed over a long time period, and the process ended about 3.5 billion years ago. Therefore, in the structure of the code, traces of its evolution can be traced, from the moment of its inception to the present day.

When talking about the sequence of elements in the genetic code, it means that it is far from being chaotic, but has a strictly defined order. And this also largely determines the properties of the genetic code. This is equivalent to the arrangement of letters and syllables in words. It is worth breaking the usual order, and most of what we will read on the pages of books or newspapers will turn into ridiculous gibberish.

Basic properties of the genetic code

Usually the code carries some information encrypted in a special way. In order to decipher the code, you need to know distinctive features.

So, basic properties the genetic code is:

• triplet;
• degeneracy or redundancy;
• uniqueness;
• continuity;
• the versatility already mentioned above.

Let's take a closer look at each property.

1. Tripletity

This is when three nucleotide compounds form a sequential chain within a molecule (i.e. DNA or RNA). As a result, a triplet compound is created or encodes one of the amino acids, its location in the peptide chain.

Codons (they are code words!) are distinguished by their connection sequence and by the type of those nitrogenous compounds (nucleotides) that are part of them.

In genetics, it is customary to distinguish 64 codon types. They can form combinations of four types 3 nucleotides each. This is equivalent to raising the number 4 to the third power. Thus, the formation of 64 nucleotide combinations is possible.

2. Redundancy of the genetic code

This property is observed when several codons are required to encrypt one amino acid, usually within 2-6. And only tryptophan can be encoded with a single triplet.

3. Uniqueness

It is included in the properties of the genetic code as an indicator of healthy gene inheritance. For example, the GAA triplet in sixth place in the chain can tell doctors about a good state of blood, about normal hemoglobin. It is he who carries information about hemoglobin, and it is also encoded by him. And if a person is anemic, one of the nucleotides is replaced by another letter of the code - U, which is a signal of the disease.

4. Continuity

When writing this property of the genetic code, it should be remembered that codons, like chain links, are located not at a distance, but in direct proximity, one after another in the nucleic acid chain, and this chain is not interrupted - it has no beginning or end.

5. Versatility

It should never be forgotten that everything on Earth is united by a common genetic code. And therefore, in a primate and a man, in an insect and a bird, a hundred-year-old baobab and a blade of grass barely hatched from the ground, similar amino acids are encoded in identical triplets.

It is in the genes that the basic information about the properties of an organism is stored, a kind of program that the organism inherits from those who lived earlier and which exists as a genetic code.

Gene classification

1) By the nature of the interaction in the allelic pair:

Dominant (a gene capable of suppressing the manifestation of an allelic recessive gene); - recessive (a gene, the manifestation of which is suppressed by an allelic dominant gene).

2) Functional classification:

2) Genetic code- these are certain combinations of nucleotides and the sequence of their location in the DNA molecule. This is a way of encoding the amino acid sequence of proteins using a sequence of nucleotides, characteristic of all living organisms.

Four nucleotides are used in DNA - adenine (A), guanine (G), cytosine (C), thymine (T), which in Russian-language literature are denoted by the letters A, G, T and C. These letters make up the alphabet of the genetic code. In RNA, the same nucleotides are used, with the exception of thymine, which is replaced by a similar nucleotide - uracil, which is denoted by the letter U (U in Russian-language literature). In DNA and RNA molecules, nucleotides line up in chains and, thus, sequences of genetic letters are obtained.

Genetic code

There are 20 different amino acids used in nature to build proteins. Each protein is a chain or several chains of amino acids in a strictly defined sequence. This sequence determines the structure of the protein, and therefore all its biological properties. The set of amino acids is also universal for almost all living organisms.

The implementation of genetic information in living cells (i.e., the synthesis of a protein encoded by a gene) is carried out using two matrix processes: transcription (i.e., mRNA synthesis on a DNA template) and translation of the genetic code into an amino acid sequence (synthesis of a polypeptide chain on an mRNA template). Three consecutive nucleotides are enough to encode 20 amino acids, as well as the stop signal, which means the end of the protein sequence. A set of three nucleotides is called a triplet. Accepted abbreviations corresponding to amino acids and codons are shown in the figure.

Properties of the genetic code

1. Tripletity- a significant unit of the code is a combination of three nucleotides (triplet, or codon).

2. Continuity- there are no punctuation marks between the triplets, that is, the information is read continuously.

3. discreteness- the same nucleotide cannot be simultaneously part of two or more triplets.

4. Specificity- a certain codon corresponds to only one amino acid.

5. Degeneracy (redundancy) Several codons can correspond to the same amino acid.

6. Versatility - genetic code works the same way in organisms different levels complexity - from viruses to humans. (genetic engineering methods are based on this)

3) transcription - the process of RNA synthesis using DNA as a template that occurs in all living cells. In other words, it is the transfer of genetic information from DNA to RNA.

Transcription is catalyzed by the enzyme DNA-dependent RNA polymerase. The process of RNA synthesis proceeds in the direction from 5 "- to 3" - end, that is, RNA polymerase moves along the template DNA chain in the direction 3 "-> 5"

Transcription consists of the stages of initiation, elongation and termination.

Transcription initiation - difficult process, which depends on the DNA sequence near the transcribed sequence (and in eukaryotes also on more distant parts of the genome - enhancers and silencers) and on the presence or absence of various protein factors.

Elongation- Further unwinding of DNA and RNA synthesis along the coding chain continues. it, like DNA synthesis, is carried out in the direction 5-3

Termination- as soon as the polymerase reaches the terminator, it is immediately cleaved from DNA, the local DNA-RNA hybrid is destroyed and the newly synthesized RNA is transported from the nucleus to the cytoplasm, at which transcription is completed.

Processing- a set of reactions leading to the transformation of the primary products of transcription and translation into functioning molecules. Items are subject to functionally inactive precursor molecules decomp. ribonucleic acid (tRNA, rRNA, mRNA) and many others. proteins.

In the process of synthesis of catabolic enzymes (cleaving substrates), prokaryotes undergo induced synthesis of enzymes. This gives the cell the ability to adapt to conditions. environment and save energy by stopping the synthesis of the corresponding enzyme if the need for it disappears.
To induce the synthesis of catabolic enzymes, the following conditions are required:

1. The enzyme is synthesized only when the cleavage of the corresponding substrate is necessary for the cell.
2. The substrate concentration in the medium must exceed a certain level before the corresponding enzyme can be formed.
The mechanism of regulation of gene expression in Escherichia coli is best studied using the example of the lac operon, which controls the synthesis of three catabolic enzymes that break down lactose. If there is a lot of glucose and little lactose in the cell, the promoter remains inactive, and the repressor protein is located on the operator - transcription of the lac operon is blocked. When the amount of glucose in the environment, and therefore in the cell, decreases, and lactose increases, the following events occur: the amount of cyclic adenosine monophosphate increases, it binds to the CAP protein - this complex activates the promoter to which RNA polymerase binds; at the same time, excess lactose binds to the repressor protein and releases the operator from it - the path for RNA polymerase is open, transcription of the structural genes of the lac operon begins. Lactose acts as an inductor for the synthesis of those enzymes that break it down.

5) Regulation of gene expression in eukaryotes is much more difficult. different types cells of a multicellular eukaryotic organism synthesize a number of identical proteins and at the same time they differ from each other in a set of proteins specific to cells of this type. The level of production depends on the type of cells, as well as on the stage of development of the organism. Gene expression is regulated at the cell level and at the organism level. The genes of eukaryotic cells are divided into two main types: the first determines the universality of cellular functions, the second determines (determines) specialized cellular functions. Gene Functions first group appear in all cells. To carry out differentiated functions, specialized cells must express a certain set of genes.
Chromosomes, genes, and operons of eukaryotic cells have a number of structural and functional features, which explains the complexity of gene expression.
1. Operons of eukaryotic cells have several genes - regulators, which can be located on different chromosomes.
2. Structural genes that control the synthesis of enzymes of one biochemical process can be concentrated in several operons located not only in one DNA molecule, but also in several.
3. Complex sequence of the DNA molecule. There are informative and non-informative sections, unique and repeatedly repeated informative nucleotide sequences.
4. Eukaryotic genes consist of exons and introns, and mRNA maturation is accompanied by excision of introns from the corresponding primary RNA transcripts (pro-i-RNA), i.e. splicing.
5. The process of gene transcription depends on the state of chromatin. Local compaction of DNA completely blocks RNA synthesis.
6. Transcription in eukaryotic cells is not always associated with translation. The synthesized mRNA can be stored as informosomes for a long time. Transcription and translation occur in different compartments.
7. Some eukaryotic genes have non-permanent localization (labile genes or transposons).
8. Methods of molecular biology revealed the inhibitory effect of histone proteins on the synthesis of mRNA.
9. In the process of development and differentiation of organs, the activity of genes depends on hormones circulating in the body and causing specific reactions in certain cells. In mammals, the action of sex hormones is important.
10. In eukaryotes, 5-10% of genes are expressed at each stage of ontogenesis, the rest should be blocked.

6) reparation genetic material

Genetic repair- the process of eliminating genetic damage and restoring the hereditary apparatus, which occurs in the cells of living organisms under the action of special enzymes. The ability of cells to repair genetic damage was first discovered in 1949 by the American geneticist A. Kelner. Repair- a special function of cells, which consists in the ability to correct chemical damage and breaks in DNA molecules damaged during normal DNA biosynthesis in the cell or as a result of exposure to physical or chemical agents. It is carried out by special enzyme systems of the cell. A number of hereditary diseases (eg, xeroderma pigmentosum) are associated with impaired repair systems.

types of reparations:

Direct repair is the simplest way to eliminate damage in DNA, which usually involves specific enzymes that can quickly (usually in one stage) repair the corresponding damage, restoring the original structure of nucleotides. This is how, for example, O6-methylguanine-DNA-methyltransferase acts, which removes the methyl group from the nitrogenous base to one of its own cysteine ​​residues.

Hereditary information is information about the structure of a protein (information about which amino acids in what order combine during the synthesis of the primary structure of the protein).

Information about the structure of proteins is encoded in DNA, which in eukaryotes is part of the chromosomes and is located in the nucleus. The section of DNA (chromosome) that encodes information about one protein is called gene.

Transcription- this is the rewriting of information from DNA to mRNA (messenger RNA). mRNA carries information from the nucleus to the cytoplasm, to the site of protein synthesis (to the ribosome).

Broadcast is the process of protein biosynthesis. Inside the ribosome, tRNA anticodons are attached to mRNA codons according to the principle of complementarity. The ribosome links the amino acids brought by the tRNA with a peptide bond to form a protein.

The reactions of transcription, translation, and replication (doubling of DNA) are reactions matrix synthesis. DNA serves as a template for mRNA synthesis, mRNA serves as a template for protein synthesis.

Genetic code is the way in which information about the structure of a protein is recorded in DNA.

Genecode Properties

1) Tripletity: one amino acid is encoded by three nucleotides. These 3 nucleotides in DNA are called a triplet, in mRNA - a codon, in tRNA - an anticodon (but in the exam there may be a “code triplet”, etc.)

2) Redundancy(degeneracy): there are only 20 amino acids, and there are 61 triplets encoding amino acids, so each amino acid is encoded by several triplets.

3) Unambiguity: each triplet (codon) codes for only one amino acid.

4) Versatility: the genetic code is the same for all living organisms on Earth.

Tasks

Tasks for the number of nucleotides / amino acids
3 nucleotides = 1 triplet = 1 amino acid = 1 tRNA

Tasks at ATHC
DNA mRNA tRNA
A U A
T A U
G C G
C G C

Choose the one most correct option. mRNA is a copy
1) one gene or group of genes
2) chains of a protein molecule
3) one protein molecule
4) parts of the plasma membrane

Answer

Choose one, the most correct option. The primary structure of a protein molecule, given by the mRNA nucleotide sequence, is formed in the process
1) broadcasts
2) transcriptions
3) reduplication
4) denaturation

Answer

Choose one, the most correct option. Which sequence correctly reflects the way of realization of genetic information
1) gene --> mRNA --> protein --> trait
2) trait --> protein --> mRNA --> gene --> DNA
3) mRNA --> gene --> protein --> trait
4) gene --> DNA --> trait --> protein

Answer

Choose one, the most correct option. Select correct sequence transmission of information in the process of protein synthesis in the cell
1) DNA -> messenger RNA -> protein
2) DNA -> transfer RNA -> protein
3) ribosomal RNA -> transfer RNA -> protein
4) ribosomal RNA -> DNA -> transfer RNA -> protein

Answer

Choose one, the most correct option. The same amino acid corresponds to the CAA anticodon on transfer RNA and the triplet on DNA
1) CAA
2) TSUU
3) GTT
4) GAA

Answer

Choose one, the most correct option. AAU anticodon on transfer RNA corresponds to a triplet on DNA
1) TTA
2) AAT
3) AAA
4) TTT

Answer

Choose one, the most correct option. Each amino acid in a cell is encoded
1) one DNA molecule
2) several triplets
3) multiple genes
4) one nucleotide

Answer

Choose one, the most correct option. Functional unit of the genetic code
1) nucleotide
2) triplet
3) amino acid
4) tRNA

Answer

Choose three options. As a result of reactions of the matrix type, molecules are synthesized
1) polysaccharides
2) DNA
3) monosaccharides
4) mRNA
5) lipids
6) squirrel

Answer

1. Determine the sequence of processes that provide protein biosynthesis. Write down the corresponding sequence of numbers.
1) the formation of peptide bonds between amino acids
2) attachment of the tRNA anticodon to the complementary mRNA codon
3) synthesis of mRNA molecules on DNA
4) movement of mRNA in the cytoplasm and its location on the ribosome
5) delivery of amino acids to the ribosome using tRNA

Answer

2. Establish the sequence of protein biosynthesis processes in the cell. Write down the corresponding sequence of numbers.
1) the formation of a peptide bond between amino acids
2) interaction of mRNA codon and tRNA anticodon
3) release of tRNA from the ribosome
4) connection of mRNA with a ribosome
5) release of mRNA from the nucleus into the cytoplasm
6) mRNA synthesis

Answer

3. Set the sequence of processes in protein biosynthesis. Write down the corresponding sequence of numbers.
1) mRNA synthesis on DNA
2) amino acid delivery to the ribosome
3) formation of a peptide bond between amino acids
4) attachment of an amino acid to tRNA
5) mRNA connection with two ribosome subunits

Answer

4. Set the sequence of steps in protein biosynthesis. Write down the corresponding sequence of numbers.
1) separation of a protein molecule from a ribosome
2) attachment of tRNA to the start codon
3) transcription
4) elongation of the polypeptide chain
5) release of mRNA from the nucleus into the cytoplasm

Answer

5. Set the correct sequence of protein biosynthesis processes. Write down the corresponding sequence of numbers.
1) attachment of an amino acid to a peptide
2) mRNA synthesis on DNA
3) codon recognition of anticodon
4) association of mRNA with a ribosome
5) release of mRNA into the cytoplasm

Answer

Choose one, the most correct option. Which transfer RNA anticodon corresponds to the TGA triplet in the DNA molecule
1) ACU
2) ZUG
3) UGA
4) AHA

Answer

Choose one, the most correct option. The genetic code is universal because
1) each amino acid is encoded by a triplet of nucleotides
2) the place of an amino acid in a protein molecule is determined by different triplets
3) it is the same for all creatures living on Earth
4) several triplets code for one amino acid

Answer

Choose one, the most correct option. The section of DNA containing information about one polypeptide chain is called
1) chromosome
2) triplet
3) genome
4) code

Answer

Choose one, the most correct option. Translation is the process by which
1) the number of DNA strands doubles
2) mRNA is synthesized on the DNA template
3) proteins are synthesized on the mRNA template in the ribosome
4) hydrogen bonds between DNA molecules are broken

Answer

Choose three options. Protein biosynthesis, unlike photosynthesis, occurs
1) in chloroplasts
2) in mitochondria
3) in plastic exchange reactions
4) in reactions of the matrix type
5) in lysosomes
6) in leukoplasts

Answer

Choose one, the most correct option. The translation matrix is ​​the molecule
1) tRNA
2) DNA
3) rRNA
4) mRNA

Answer

All but two of the features below can be used to describe the functions of nucleic acids in a cell. Identify two features that "drop out" of general list, and write down in the table the numbers under which they are indicated.
1) carry out homeostasis
2) transfer hereditary information from the nucleus to the ribosome
3) participate in protein biosynthesis
4) are part of the cell membrane
5) transport amino acids

Answer

AMINO ACIDS - CODONS mRNA
How many mRNA codons encode information about 20 amino acids? Write down only the appropriate number in your answer.

Answer

AMINO ACIDS - NUCLEOTIDES mRNA
1. The polypeptide region consists of 28 amino acid residues. Determine the number of nucleotides in the mRNA region containing information about the primary structure of the protein.

Answer

2. How many nucleotides does mRNA contain if the protein synthesized from it consists of 180 amino acid residues? Write down only the appropriate number in your answer.

Answer

AMINO ACIDS - DNA NUCLEOTIDES
1. Protein consists of 140 amino acid residues. How many nucleotides are in the region of the gene in which the primary structure of this protein is encoded?

Answer

2. Protein consists of 180 amino acid residues. How many nucleotides are in the gene that encodes the sequence of amino acids in this protein. Write down only the appropriate number in your answer.

Answer

3. A fragment of a DNA molecule encodes 36 amino acids. How many nucleotides does this DNA fragment contain? Write down the corresponding number in your answer.

Answer

4. The polypeptide consists of 20 amino acid units. Determine the number of nucleotides in the gene region encoding these amino acids in the polypeptide. Write your answer as a number.

Answer

5. How many nucleotides in the gene region encode a protein fragment of 25 amino acid residues? Write down the correct number for your answer.

Answer

6. How many nucleotides in a fragment of the DNA template chain encode 55 amino acids in a polypeptide fragment? Write down only the appropriate number in your answer.

Answer

AMINO ACIDS - tRNA
1. How many tRNAs took part in protein synthesis, which includes 130 amino acids? Write the correct number in your answer.

Answer

2. A fragment of a protein molecule consists of 25 amino acids. How many tRNA molecules were involved in its creation? Write down only the appropriate number in your answer.

Answer

AMINO ACIDS - TRIPLETS
1. How many triplets does a fragment of a DNA molecule contain, encoding 36 amino acids? Write down the corresponding number in your answer.

Answer

2. How many triplets encode 32 amino acids? Write down the correct number for your answer.

Answer

NUCLEOTIDES - AMINO ACIDS
1. What is the number of amino acids encoded in the gene section containing 129 nucleotide residues?

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2. How many amino acids does 900 nucleotides encode? Write down the correct number for your answer.

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3. What is the number of amino acids in a protein if its coding gene consists of 600 nucleotides? Write down the correct number for your answer.

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4. How many amino acids does 1203 nucleotides encode? In response, write down only the number of amino acids.

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5. How many amino acids are needed for the synthesis of a polypeptide if the mRNA encoding it contains 108 nucleotides? Write down only the appropriate number in your answer.

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mRNA NUCLEOTIDES - DNA NUCLEOTIDES
An mRNA molecule takes part in protein synthesis, the fragment of which contains 33 nucleotide residues. Determine the number of nucleotide residues in the region of the DNA template chain.

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NUCLEOTIDES - tRNA
How many transport RNA molecules were involved in translation if the gene section contains 930 nucleotide residues?

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TRIPLETS - NUCLEOTIDES mRNA
How many nucleotides are in a fragment of an mRNA molecule if the fragment of the DNA coding chain contains 130 triplets? Write down only the appropriate number in your answer.

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tRNA - AMINO ACIDS
Determine the number of amino acids in a protein if 150 tRNA molecules were involved in the translation process. Write down only the appropriate number in your answer.

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SIMPLY
How many nucleotides make up one mRNA codon?

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How many nucleotides make up one mRNA stop codon?

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How many nucleotides make up a tRNA anticodon?

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DIFFICULT
The protein has a relative molecular weight of 6000. Determine the number of amino acids in a protein molecule if the relative molecular weight of one amino acid residue is 120. In your answer, write down only the corresponding number.

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There are 3,000 nucleotides in two strands of a DNA molecule. Information about the protein structure is encoded on one of the chains. Count how many amino acids are encoded on one strand of DNA. In response, write down only the number corresponding to the number of amino acids.

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Choose one, the most correct option. The same amino acid corresponds to a UCA anticodon on transfer RNA and a triplet in a gene on DNA
1) GTA
2) ACA
3) TGT
4) TCA

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Choose one, the most correct option. The synthesis of hemoglobin in the cell controls a certain segment of the DNA molecule, which is called
1) codon
2) triplet
3) genetic code
4) genome

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In which of the following cell organelles do matrix synthesis reactions take place? Identify three true statements from the general list, and write down the numbers under which they are indicated.
1) centrioles
2) lysosomes
3) Golgi apparatus
4) ribosomes
5) mitochondria
6) chloroplasts

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Consider the picture depicting the processes occurring in the cell, and indicate A) the name of the process, indicated by the letter A, B) the name of the process, indicated by the letter B, C) the name of the type chemical reactions. For each letter, select the appropriate term from the list provided.
1) replication
2) transcription
3) broadcast
4) denaturation
5) exothermic reactions
6) substitution reactions
7) matrix synthesis reactions
8) cleavage reactions

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Look at the picture and write (A) the name of process 1, (B) the name of process 2, (c) the end product of process 2. For each letter, select the appropriate term or concept from the list provided.
1) tRNA
2) polypeptide
3) ribosome
4) replication
5) broadcast
6) conjugation
7) ATP
8) transcription

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Establish a correspondence between the processes and stages of protein synthesis: 1) transcription, 2) translation. Write the numbers 1 and 2 in the correct order.
A) t-RNA amino acid transfer
B) DNA is involved
C) i-RNA synthesis
D) formation of a polypeptide chain
D) occurs on the ribosome

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All of the features listed below, except for two, are used to describe the process depicted in the figure. Identify two signs that “fall out” from the general list, and write down the numbers under which they are indicated.
1) according to the principle of complementarity, the nucleotide sequence of a DNA molecule is translated into a nucleotide sequence of molecules various kinds RNA
2) the process of translating a nucleotide sequence into an amino acid sequence
3) the process of transferring genetic information from the nucleus to the site of protein synthesis
4) the process takes place in ribosomes
5) the result of the process - RNA synthesis

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The molecular weight of the polypeptide is 30,000 USD. Determine the length of the gene encoding it if the molecular weight of one amino acid is on average 100, and the distance between nucleotides in DNA is 0.34 nm. Write down only the appropriate number in your answer.

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Choose from the reactions listed below two related to the reactions of matrix synthesis. Write down the numbers under which they are indicated.
1) cellulose synthesis
2) ATP synthesis
3) protein biosynthesis
4) glucose oxidation
5) DNA replication

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Choose three correct answers from six and write down the numbers under which they are indicated in the table. Matrix reactions in the cell include
1) DNA replication
2) photolysis of water
3) RNA synthesis
4) chemosynthesis
5) protein biosynthesis
6) ATP synthesis

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All of the following features, except for two, can be used to describe the process of protein biosynthesis in a cell. Identify two features that “fall out” of the general list, and write down in response the numbers under which they are indicated.
1) The process occurs in the presence of enzymes.
2) The central role in the process belongs to RNA molecules.
3) The process is accompanied by the synthesis of ATP.
4) Amino acids serve as monomers for the formation of molecules.
5) The assembly of protein molecules is carried out in lysosomes.

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Find three errors in the given text. Specify the numbers of proposals in which they are made.(1) During protein biosynthesis, matrix synthesis reactions occur. (2) Matrix synthesis reactions include only replication and transcription reactions. (3) As a result of transcription, mRNA is synthesized, the template for which is the entire DNA molecule. (4) After passing through the pores of the nucleus, mRNA enters the cytoplasm. (5) Messenger RNA is involved in the synthesis of tRNA. (6) Transfer RNA provides amino acids for protein assembly. (7) The energy of ATP molecules is spent on the connection of each of the amino acids with tRNA.

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All but two of the following concepts are used to describe translation. Identify two signs that “fall out” from the general list, and write down the numbers under which they are indicated.
1) matrix synthesis
2) mitotic spindle
3) polysome
4) peptide bond
5) higher fatty acids

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