What are the functions of nucleic acids in a cell? Structure and functions of nucleic acids.

Molecular basis of heredity and variability

1. Nucleic acids, their structure, functions and genesis

2. The main stages of protein biosynthesis. Genetic code, its main properties

3. Regulation of gene expression

Nucleic acids, their structure and functions

Nucleic acids are linear unbranched heteropolymers whose monomers are nucleotides related phosphodiester bonds.

Nucleotides- These are organic substances whose molecules consist of a pentose residue (ribose or deoxyribose), to which a phosphoric acid residue and a nitrogenous base are covalently attached. The nitrogenous bases in nucleotides are divided into two groups: purine(adenine and guanine) and pyrimidine(cytosine, thymine and uracil). Deoxyribonucleotides include in their deoxyribose adenine(A), guanine(G), thymine(T), cytosine(C). Ribonucleotides include in their ribose and one of the nitrogenous bases: adenine(A), guanine(G), uracil(U) cytosine(C).

In a number of cases, various derivatives of the listed nitrogenous bases are also found in cells - minor bases that are part of minor nucleotides.

Free nucleotides and substances similar to them play an important role in metabolism. For example, NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate) serve as electron and proton carriers.

Free nucleotides are able to add 1...2 more phosphorus groups, forming macroergic compounds. The universal source of energy in the cell is ATP - adenosine triphosphoric acid, consisting of adenine, ribose and three residues of phosphoric (pyrophosphoric) acid. Hydrolysis of one terminal pyrophosphate bond releases about 30.6 kJ/mol (or 8.4 kcal/mol) of free energy, which can be used by the cell. This pyrophosphate bond is called macroergic(high energy).

In addition to ATP, there are other high-energy compounds based on nucleotides: GTP (contains guanine; participates in the biosynthesis of proteins, glucose), UTP (contains uracil; participates in the synthesis of polysaccharides).

Nucleotides are able to form cyclic forms e.g. cAMP, cCMP, cGMP. Cyclic nucleotides act as regulators of various physiological processes.

Nucleic acids

There are two types of nucleic acids: DNA ( Deoxyribonucleic acid) and RNA ( ribonucleic acid). Nucleic acids provide storage, reproduction and implementation of genetic (hereditary) information. This information is reflected (encoded) in the form of nucleotide sequences. In particular, the nucleotide sequence reflects the primary structure of proteins (see below). The correspondence between amino acids and the nucleotide sequences that encode them is called genetic code . unit genetic code DNA and RNA is triplet- a sequence of three nucleotides.

Nucleic acids are chemically active substances. They form a variety of compounds with proteins - nucleoproteins, or nucleoproteins.

Deoxyribonucleic acid (DNA) is a nucleic acid whose monomers are deoxyribonucleotides. DNA is the primary carrier of hereditary information. This means that all information about the structure, functioning and development of individual cells and the whole organism is recorded in the form of DNA nucleotide sequences.

Nucleic acids were discovered by Miescher in 1868. However, only in 1924 did Fölgen prove that DNA is an essential component of chromosomes. In 1944, Avery, McLeod and McCarthy established that DNA plays a decisive role in the storage, transmission and implementation of hereditary information.

There are several types of DNA: A, B, Z, T-forms. Of these, the B-form is usually found in cells - a double right-handed helix, which consists of two threads (or chains) interconnected by hydrogen bonds. Each strand is represented by alternating residues of deoxyribose and phosphoric acid, moreover, a nitrogenous base is covalently attached to deoxyribose. In this case, the nitrogenous bases of the two strands of DNA are directed towards each other and, due to the formation of hydrogen bonds, form complementary pairs: A=T (two hydrogen bonds) and G≡C (three hydrogen bonds). Therefore, the nucleotide sequences of these chains uniquely correspond to each other. The length of the coil of the double helix is ​​3.4 nm, the distance between adjacent pairs of nitrogenous bases is 0.34 nm, and the diameter of the double helix is ​​1.8 nm.

In eukaryotic cells, DNA exists in the form of nucleoprotein complexes, which include histone proteins.

The length of DNA is measured by the number of nucleotide pairs (abbreviated - Mon, or b). The length of one DNA molecule ranges from several thousand Mon(abbreviated - tbn, or kb) up to several million Mon (mpn, or Mb).

ChapterV. NUCLEIC ACIDS

§ 13. NUCLEIC ACIDS:

FUNCTIONS AND COMPOSITION

General ideas about nucleic acids

Nucleic acids are the most important biopolymers with a relative molecular weight reaching 5·10 9 . They are contained in all living organisms without exception and are not only the custodian and source of genetic information, but also perform a number of other vital functions. Nucleic acids are polymers whose monomer units are nucleotides.

There are two different types of nucleic acids − deoxyribonucleic acids(DNA) and ribonucleic acids(RNA). DNA is the genetic material of most organisms. In prokaryotic cells, in addition to the main chromosomal DNA, extrachromosomal DNA, plasmids, are often found. In eukaryotic cells, the bulk of DNA is located in the cell nucleus, where it is associated with proteins in the chromosomes. Eukaryotic cells also contain DNA in mitochondria and chloroplasts.

Interesting to know! DNA molecules are the largest molecules. DNA moleculeE. coliconsists of approximately 4,000,000 base pairs, its relative mass is 26000000000, and its length is 1.4 mm, which is 700 times the size of its cell. Eukaryotic DNA molecules can reach even larger sizes, their length can be several cm, and their relative mass is 10 10 -10 11 . It would take about 1,000,000 pages to write down the nucleotide sequence of human DNA.

As for RNA, according to the functions they perform, they distinguish:

1. information RNA (mRNA) - they contain information about the primary structure of the protein;

2. ribosomal RNA (rRNA) - are part of ribosomes;

3. transport RNA (tRNA) - provide delivery of amino acids to the site of protein synthesis.

As the genetic material, RNA is part of a number of viruses. For example, viruses that cause dangerous diseases, like the flu and AIDS, are RNA-containing.

Nucleic acids can be linear and circular (covalently closed). They may consist of one or two chains. Below is a diagram showing the existence in nature of various types of nucleic acids:

Functions of Nucleic Acids

Nucleic acids have three important functions: storage, transmission and implementation of genetic information. In addition to these, they perform other functions, for example, they are involved in the catalysis of some chemical reactions, regulate the implementation of genetic information, perform structural functions, etc. The role of the custodian of genetic information in most organisms (eukaryotes, prokaryotes, some viruses) is performed by double-stranded DNA. Only in some viruses, the custodian of genetic information is single-stranded DNA or single-stranded, as well as double-stranded RNA. Genetic information is stored in genes. A gene, by its very nature, is a section of nucleic acid. They encode the primary structure of proteins. Genes can also carry information about the structure of certain types of RNA, such as tRNA and rRNA.

Genetic information is passed from parents to offspring. This process is associated with the doubling of nucleic acid (DNA or RNA), which acts as a custodian of genetic information, and its subsequent transfer to descendants. For example, as a result of division, daughter cells receive identical DNA molecules from the mother, and therefore identical genetic information (Fig. 38). During reproduction, viruses also pass on to their daughter virus particles. exact copies nucleic acid. In sexual reproduction, offspring receive genetic information from both parents. This is why children inherit traits from both parents.

Rice. 38. DNA distribution during cell division

As a result of the implementation of genetic information, the synthesis of proteins encoded in DNA in the form of genes (or, for some viruses, in RNA) occurs. In this process, information about the primary structure of the protein is copied from the DNA molecule to mRNA and then decoded on ribosomes with the participation of tRNA. As a result, a protein is formed:

DNA RNA protein.

Composition of nucleic acids

Nucleic acids are polymers built from nucleotides linked together by phosphodiester bonds. Each nucleotide consists of nitrogenous base, pentose and phosphoric acid residues.

Distinguish pyrimidine And purine grounds, also called respectively pyrimidines And purines. Pyrimidine bases are pyrimidine derivatives:

purine bases - derivatives purine:

Pyrimidines include uracil, thymine, and cytosine; purines include adenine and guanine:

DNA contains thymine, cytosine, adenine and guanine, while RNA contains the same bases, only uracil is included instead of thymine. In addition to nitrogenous bases, nucleic acids contain pentoses: DNA - D-deoxyribose, and RNA - D-ribose. Carbohydrates are in the form of the b-anomer of the furanose form:

The nitrogenous base binds to the carbohydrate at the expense of the glycosidic hydroxyl. A nucleoside is formed. Schematically, the formation of a nucleoside can be depicted as follows:

The composition of nucleic acids includes 8 nucleosides, 4 - in the composition of RNA and 4 - in the composition of DNA (Fig. 39).

Nucleosides that make up RNA:

Nucleosides that make up DNA:

Rice. 39. Nucleosides

A nucleoside bound to a phosphoric acid residue is called a nucleotide:

In this case, the phosphoric acid residue can be associated with a 3'- or 5'- carbon atom:

Adenosine 5'-monophosphate is abbreviated as AMP. If a nucleotide is formed by deoxoribose, adenine, and one phosphoric acid residue, then it will be called deoxyadenosine monophosphate, or dAMP for short. Table 5 shows the nucleotide nomenclature.

Table 5

Nomenclature of the nucleotides that form DNA and RNA

nitrogenous base	Nucleoside	Nucleotide
		full title	abbreviation
	adenosine Deoxyadenosine	Adenosine monophosphate Deoxyadenosine monophosphate
	Guanosine Deoxyguanosine	Guanosine monophosphate Deoxyguanosine monophosphate
	Deoxycytidine	Cytidine monophosphate Deoxycytidine monophosphate
		Uridine monophosphate
	Deoxythymidine	Deoxythymidine monophosphate

Nucleoside monophosphates (NMP) and deoxynucleoside monophosphates (dNMP) can be joined by 1 or 2 more phosphoric acid residues. This produces nucleoside diphosphates (NDPs), deoxynucleoside diphosphates (dNDPs), or nucleoside triphosphates (NTPs) and deoxynucleoside triphosphates (dNTPs).

NTP and dNTP serve as substrates for RNA and DNA synthesis, respectively.

Nucleic acids.

Nucleic acids- natural high-molecular biopolymers that provide storage and transmission of hereditary (genetic) information in living organisms.

A macromolecule of nucleic acids, with a molecular weight from 10,000 Daltons to several million, was discovered in 1869 by the Swiss chemist F. Miescher in the nuclei of leukocytes that make up pus, hence the name (nucleus - nucleus).

Nucleic acids are polymers whose monomers are nucleotides . Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphoric acid residue. Long molecules are built from nucleotides. polynucleotides .

Phosphate

nitrogenous

base

Connection between

phosphate and sugar

Rice. The structure of a nucleotide.

Sugar, which is part of the nucleotide, contains five carbon atoms, that is, it is pentose . Depending on the type of pentose present in the nucleotide, there are two types of nucleic acids - ribonucleic acids (RNA), which contain ribose , and deoxyribonucleic acids (DNA) containing deoxyribose (C 5 H 10 O 4).

Foundations, both types of nucleic acids contain four different types: two of them belong to the class purines and two - to the class pyrimidines . The purines are adenine (A) and guanine (D), and to the number of pyrimidines - cytisine (C) and thymine (T) or uracil (Y) (respectively in DNA or RNA).

Nucleic acids are acids because they contain phosphoric acid.

The role of nucleotides in the body is not limited to serving as the building blocks of nucleic acids; some important coenzymes are also present in the owl nucleotides. These are, for example, adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD), nicotinamide adenine dinucleotide phosphate (NADP), and flavin adenine dinucleotide (FAD).

Nucleic acids

DNARNA

nuclear cytoplasmic mRNA tRNA rRNA

Currently known big number varieties of DNA and RNA, different from each other in structure and significance in metabolism.

Example: bacteria in Escherichia coli cells contain about 1000 different nucleic acids, while animals and plants have even more.

Each type of organism contains its own, characteristic only for it, set of these acids. DNA is localized mainly in the chromosomes of the cell nucleus (99% of the total cell DNA), as well as in mitochondria and chloroplasts. RNA is part of the nucleolus, ribosomes of mitochondria, plastids and cytoplasm.

The DNA molecule is the universal carrier of genetic information in cells. It is thanks to the structure and functions of this molecule that signs are inherited - from parents to descendants, i.e. the universal property of the living is realized - heredity. DNA molecules are the largest biopolymers.

The structure of DNA.

The structure of DNA molecules was deciphered in 1953 by J. Watson and F. Crick. They received the Nobel Prize for this discovery.

According to Watson-Crick DNA models, the DNA molecule consists of two polynucleotide chains twisted to the right around the same axes , forming double helix . The chains are arranged antiparallel, i.e. towards each other. Two polynucleotide chains are combined into a single DNA molecule using hydrogen bonds that occur between the nitrogenous base of the nucleotides of different chains. In a polynucleotide chain, adjacent nucleotides are interconnected by covalent bonds that form between deoxyribose, in a DNA molecule (and ribose in RNA), of one and the phosphoric acid residue of another nucleotide.

Double helix chains complementary to each other, since base pairing occurs in strict accordance: adenine combines with thymine, and guanine with cytosine.

As a result, in every organism Fig. Pairing of nucleotides.

number adenyl nucleotides is equal to the number thymidyl, and the number guanyl- number cytidyl. This pattern is called "Chargaff's rule".

A strict correspondence of nucleotides located in paired antiparallel strands of DNA is called complementarity. This property underlies the formation of new DNA molecules based on the original molecule.

Thus, the double helix is ​​stabilized by numerous hydrogen properties (two are formed between A and T, and three are formed between G and C) and hydrophobic interactions.

Along the axis of the molecule, adjacent base pairs are located at a distance of 0.34 nm from one another. A full turn of the helix falls on 3.4 nm, i.e., 10 base pairs (one turn). The helix diameter is 2 nm. The distance between the carbohydrate components of two paired nucleotides is 1.1 nm. The length of the nucleic acid molecule reaches hundreds of thousands of nanometers. This is much larger than the largest protein macromolecule, which, when unfolded, reaches a length of no more than 100–200 nm. The mass of a DNA molecule is 6 * 10 -12 g.

The process of duplicating a DNA molecule is called replication . Replication occurs as follows. Under the action of special enzymes (helicase), hydrogen bonds between the nucleotides of two chains are broken. The spiral unwinds. According to the principle of complementarity, the corresponding DNA nucleotides are attached to the released bonds in the presence of the enzyme DNA polymerase. This build-up can only take place in the direction 5" → 3". This means the continuous possibility of copying only one strand of DNA (top in the figure). This process is called continuous replication. Copying another chain must start again every time, as a result, breaks appear in the chain. To eliminate them, an enzyme is needed - DNA ligase. This replication is called intermittent.

This method of DNA replication, proposed by Watson and Crick, is known as semi-conservative replication .

Therefore, the order of nucleotides in the "old" DNA strand determines the order of nucleotides in the "new", i.e. The “old” DNA chain is, as it were, a matrix for the synthesis of the “new” one. Such reactions are called reactions matrix synthesis ; they are characteristic only of living things.

Replication (reduplication) allows you to maintain the constancy of the DNA structure. The synthesized DNA molecule is absolutely identical to the original in nucleotide sequence. If under the influence of various factors in the process of replication in the DNA molecule changes occur in the number and sequence of nucleotides, then mutations occur. The ability of DNA molecules to correct emerging changes and restore the original is called reparations .

DNA functions:

1) Storage of hereditary information.

DNA stores information in the form of a sequence of nucleotides.

2) Reproduction and transmission of genetic information.

The ability to transfer information to daughter cells is provided by the ability of chromosomes to separate into chromatids with subsequent reduplication of DNA molecules. It encodes genetic information about the sequence of amino acids in a protein molecule. The section of DNA that carries information about one polypeptide chain is called a gene.

3) Structural.

DNA is present on chromosomes as structural component, i.e. is the chemical basis of the chromosomal genetic material (gene).

4) DNA is the template for creating RNA molecules.

RNA is found in all living cells as single-stranded molecules. It differs from DNA in that it contains as pentose ribose (instead of deoxyribose), and as one of the pyrimidine bases - uracil (instead of thymine). There are three types of RNA. These are matrix, or information, RNA (mRNA, mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). All three are synthesized directly from DNA, and the amount of RNA in each cell depends on the amount of protein produced by that cell.

In an RNA chain, nucleotides are linked by the formation of covalent bonds (phosphodiester bonds) between the ribose of one nucleotide and the phosphoric acid residue of another.

Unlike DNA, RNA molecules are a single-stranded linear biopolymer consisting of nucleotides.

Double-stranded RNAs serve to store and reproduce hereditary information in some viruses, i.e. they perform the functions of chromosomes - viral RNA.

Nucleotides of one RNA molecule can enter into complementary relationships with other nucleotides of the same chain, as a result of the formation of secondary and tertiary structures of RNA molecules.

Rice. The structure of transfer RNA.

Ribisomal RNA(rRNA) makes up 85% of the total RNA of the cell, it is synthesized in the nucleolus, in combination with the protein it is part of the ribosomes, mitochondria (mitochondrial RNA) and plastids (plastid RNA). Contains from 3 to 5 thousand nucleotides. Protein synthesis takes place on ribosomes.

Functions: rRNA performs a structural function (part of ribosomes) and participates in the formation of the active center of ribosomes, where peptide bonds are formed between amino acid molecules during protein biosynthesis.

Messenger RNA(mRNA) makes up 5% of all RNA in cells. It is synthesized during transcription certain area DNA molecules - gene. In terms of structure, mRNA is complementary to a section of DNA molecules that carries information about the synthesis of a particular protein. The length of the mRNA depends on the length of the DNA section from which the information was read (it can consist of 300-30000 nucleotides)

Functions: mRNA transfers information about protein synthesis from the nucleus to the cytoplasm to ribosomes and becomes a matrix for the synthesis of protein molecules.

Transfer RNA(tRNA) makes up about 10% of all RNA, is synthesized in the nucleolus, has a short chain of nucleotides and is located in the cytoplasm. It has a trefoil function. Each amino acid has its own family of tRNA molecules. They deliver the amino acids contained in the cytoplasm to the ribosome.

Functions: at one end is a triplet of nucleotides (anticodon) that codes for a specific amino acid. At the other end is a triplet of nucleotides to which an amino acid is attached. Each amino acid has its own tRNA.

Like proteins, nucleic acids are biopolymers, and their function is to store, implement and transfer genetic (hereditary) information in living organisms.

There are two types of nucleic acids - deoxyribonucleic (DNA) and ribonucleic (RNA). Monomers in nucleic acids are nucleotides. Each of them contains a nitrogenous base, a five-carbon sugar (deoxyribose in DNA, ribose in RNA) and a phosphoric acid residue.

DNA contains four types of nucleotides that differ in the nitrogenous base in their composition - adenine (A), guanine (G), cytosine (C) and thymine (T). The RNA molecule also has 4 types of nucleotides with one of the nitrogenous bases - adenine, guanine, cytosine and uracil (U). Thus, DNA and RNA differ both in the content of sugar in nucleotides and in one of the nitrogenous bases (Table 1).

Table 1

Components of DNA and RNA nucleotides

DNA and RNA molecules differ significantly in their structure and functions.

A DNA molecule can include a huge number of nucleotides - from several thousand to hundreds of millions (truly giant DNA molecules can be "seen" with an electron microscope). Structurally, it is a double helix of polynucleotide chains(Fig. 1) connected by hydrogen bonds between the nitrogenous bases of nucleotides. Due to this, polynucleotide chains are firmly held one next to the other.

In the study of various DNAs (in different types of organisms), it was found that adenine of one chain can only bind to thymine, and guanine can only bind to cytosine of another. Therefore, the order of the nucleotides in one strand strictly corresponds to the order of their arrangement in the other. This phenomenon has been named complementarity(i.e. additions), and the opposite polynucleotide chains are called complementary. This is the reason for the unique among all inorganic and organic matter property of DNA ability to reproduce or doubling(Fig. 2). In this case, at first, the complementary chains of DNA molecules diverge (under the influence of a special enzyme, the bonds between the complementary nucleotides of the two chains are destroyed). Then, on each chain, the synthesis of a new (“missing”) complementary chain begins due to free nucleotides, which are always present in large quantities in the cell. As a result, instead of one (“parent”) DNA molecule, two (“daughter”) new ones are formed, identical in structure and composition to each other, as well as to the original DNA molecule. This process always precedes cell division and ensures the transfer of hereditary information from the mother cell to the daughter and all subsequent generations.

Rice. 1. Double helix of DNA. Two chains are wrapped one around the other. Each chain (depicted as a ribbon) consists of alternating sugar and phosphate groups. Hydrogen bonds between nitrogenous bases (A, T, G and C) hold the two chains together

Rice. 2.DNA replication. The double helix is ​​"unfastened" byweak hydrogen bonds linking complementary bases of two chains. Each of the old chains serves as a matrixfor the formation of a new one: nucleotides with complementary bases line up against the old chain and connecttogether

RNA molecules are usually single-stranded (unlike DNA) and contain a much smaller number of nucleotides. There are three types of RNA (Table 2), which differ in the size of the molecules and the functions performed - informational (mRNA), ribosomal (rRNA) and transport (tRNA).

table 2

ThreekindRNA

Messenger RNA (i-RNA) is located in the nucleus and cytoplasm of the cell, has the longest polynucleotide chain among RNA and performs the function of transferring hereditary information from the nucleus to the cytoplasm of the cell.

Transfer RNA (t-RNA) is also found in the nucleus and cytoplasm of the cell, its chain has the most complex structure, and is also the shortest (75 nucleotides). T-RNA delivers amino acids to ribosomes during translation - protein biosynthesis.

Ribosomal RNA (r-RNA) is found in the nucleolus and ribosomes of the cell, has a chain of medium length. All types of RNA are formed during the transcription of the corresponding DNA genes.

Remember!

Why are nucleic acids classified as heteropolymers?

They consist of different monomers - nucleotides, but the nucleotides themselves differ in some structures.

What is a nucleic acid monomer?

Nucleotides

What functions of nucleic acids do you know?

Storage and transmission of hereditary information. DNA contains information about the primary structure of all proteins needed by the body. This information is recorded in a linear sequence of nucleotides. Since proteins play a primary role in the life of the body, participating in the structure, development, and metabolism, it can be argued that DNA stores information about the body. In RNA, each of its types performs its function depending on its structure. mRNA is a copy of a section of DNA that contains information about the number, composition, and sequence of amino acid residues that determine the structure and functions of a protein molecule. This RNA contains a plan for constructing a polypeptide molecule. tRNA - its role is to attach an amino acid molecule and transport it to the site of protein synthesis. rRNA - combines with a protein and forms special organelles - ribosomes, on which protein molecules are assembled in the cell of any living organism.

What properties of living things are determined directly by the structure and functions of nucleic acids?

Heredity, variability, reproduction

Review questions and assignments

1. What are nucleic acids? Why did they get such a name?

Nucleic acids are biopolymers whose monomers are nucleotides. From lat. "nucleos" - the nucleus, since these acids are located or synthesized in the nucleus, or in prokaryotes, the function of nuclear information is performed by the nucleoid (DNA or RNA).

2. What types of nucleic acids do you know?

DNA, RNA: i-RNA, t-RNA, r-RNA.

4. Name the functions of DNA. How are the structure and functions of DNA related?

Storage and transmission of hereditary information - DNA is located strictly in the nucleus.

The DNA molecule is capable of self-replication by doubling. Under the action of enzymes, the double helix of DNA unwinds, bonds between nitrogenous bases are broken.

DNA contains information about the primary structure of all proteins needed by the body. This information is recorded in a linear sequence of nucleotides.

Since proteins play a primary role in the life of the body, participating in the structure, development, and metabolism, it can be argued that DNA stores information about the body.

5. What types of RNA exist in the cell, where are they synthesized? List their functions.

i-RNA, t-RNA, r-RNA.

i-RNA - synthesized in the nucleus on the DNA template, is the basis for protein synthesis.

tRNA is the transport of amino acids to the site of protein synthesis - to ribosomes.

rRNA - synthesized in the nucleoli of the nucleus, and forms the ribosomes themselves of the cell.

All types of RNA are synthesized on a DNA template.

6. Is it enough to know which monosaccharide is a part of nucleotides in order to understand what kind of nucleic acid we are talking about?

Yes, RNA contains ribose.

DNA contains deoxyribose.

Types of RNA will not be possible to recognize by one monosaccharide.

7. A fragment of one DNA chain has the following composition: A-G-C-G-C-C-C-T-A-. Using the principle of complementarity, complete the second strand.

A-G-C-G-C-C-C-T-A

T-C-G-C-G-G-G-A-T

Think! Remember!

1. Why are there three types of RNA molecules in cells, but only one type of DNA?

DNA is the largest molecule, it cannot leave the nucleus, the pores are too small. RNA is small molecules, each performs its own function, providing various functions in the cell, while working. On the DNA matrix, many types of RNA can be simultaneously synthesized, and all of them go to perform their functions.

3. What types of RNA will be the same in all organisms? Which type of RNA has the highest variability? Explain your point of view.

i-RNA and t-RNA will be the same for all organisms, since protein biosynthesis follows a single mechanism, and t-RNA carries the same 20 amino acids. rRNA may be different.