Nucleic acids.
The history of the creation of nucleic acids DNA was discovered in 1868 by the Swiss physician I. F. Miescher in the cell nuclei of leukocytes, hence the name - nucleic acid (lat. “nucleus” - nucleus). In the 20-30s of the XX century. determined that DNA is a polymer (polynucleotide); in eukaryotic cells it is concentrated in chromosomes. It was assumed that DNA plays a structural role. In 1944, a group of American bacteriologists from the Rockefeller Institute, led by O. Avery, showed that the ability of pneumococci to cause disease is transferred from one to another through the exchange of DNA. DNA is the carrier of hereditary information.
Friedrich Fischer Swiss biochemist. From the remains of cells contained in pus, he isolated a substance that included nitrogen and phosphorus. The scientist called it nuclein, believing that it was contained only in the nucleus of the cell. Later, the non-protein part of this substance was called nucleic acid
WATSON James Dewey American biophysicist, biochemist, molecular biologist, proposed the hypothesis that DNA has the shape of a double helix, clarified the molecular structure of nucleic acids and the principle of transmission of hereditary information. Winner of the 1962 Nobel Prize in Physiology or Medicine (together with Frances Harry Compton Crick and Maurice Wilkins).
CRICK Francis Harry Compton English physicist, biophysicist, specialist in the field of molecular biology, elucidated the molecular structure of nucleic acids; Having discovered the main types of RNA, he proposed a theory of transmission of the genetic code and showed how DNA molecules are copied during cell division. in 1962 he won the Nobel Prize in Physiology or Medicine
Nucleic acids are biopolymers whose monomers are nucleotides. Each nucleotide consists of 3 parts: a nitrogenous base, a pentose monosaccharide, and a phosphoric acid residue.
NUCLEIC ACIDS MONOMERS - NUCLEOTIDES DNA - deoxyribonucleic acid RNA ribonucleic acid Composition of the nucleotide in DNA Composition of the nucleotide in RNA Nitrogenous bases: Adenine (A) Guanine (G) Cytosine (C) Uracil (U): Ribose Phosphoric acid residue Nitrogenous bases: Adenine (A ) Guanine (G) Cytosine (C) Thymine (T) Deoxyribose Phosphoric acid residue Messenger RNA (i-RNA) Transfer RNA (t-RNA) Ribosomal RNA (r-RNA) Transfer and storage of hereditary information
Chemical structure of nitrogenous bases and carbohydrates
Principle of complementarity The nitrogenous bases of two polynucleotide chains of DNA are connected to each other in pairs using hydrogen bonds according to the principle of complementarity. The pyrimidine base binds to the purine base: thymine T with adenine A (two BCs), cytosine C with guanine G (three BCs). Thus, the T content is equal to the A content, the C content is equal to the G content. Knowing the sequence of nucleotides in one DNA strand, it is possible to decipher the structure (primary structure) of the second strand. To better remember the principle of complementarity, you can use a mnemonic device: remember the phrases T games - Albino and Heron - Blue
The model of the structure of the DNA molecule was proposed by J. Watson and F. Crick in 1953. It was fully confirmed experimentally and played an extremely important role in the development of molecular biology and genetics
DNA parameters
STRUCTURES OF DNA AND RNA DNA
Structure and functions of RNA RNA is a polymer whose monomers are ribonucleotides. Unlike DNA, RNA is formed not by two, but by one polynucleotide chain (with the exception that some RNA-containing viruses have double-stranded RNA). RNA nucleotides are capable of forming hydrogen bonds with each other. RNA chains are much shorter than DNA chains.
DNA Replication The duplication of a DNA molecule is called replication or reduplication. During replication, part of the “mother” DNA molecule is unraveled into two strands with the help of a special enzyme, and this is achieved by breaking hydrogen bonds between complementary nitrogenous bases: adenine-thymine and guanine-cytosine. Next, for each nucleotide of the diverged DNA strands, the enzyme DNA polymerase adjusts a complementary nucleotide to it.
Composition and structure of RNA. Stage I of protein biosynthesis With the help of a special protein RNA polymerase, the messenger RNA molecule is built according to the principle of complementarity along a section of one DNA strand during the transcription process (the first stage of protein synthesis). The formed mRNA chain represents an exact copy of the second (non-template) DNA chain, only instead of thymine T, uracil U is included. Mnemonic: instead of T, the game - And the albino is in the weave - And the albino! mRNA
Protein biosynthesis Translation is the translation of the nucleotide sequence of an mRNA molecule (template) into the amino acid sequence of a protein molecule. The mRNA interacts with the ribosome, which begins to move along the mRNA, stopping at each section of it, which includes two codons (i.e. 6 nucleotides).
Types of RNA There are several types of RNA in a cell. All of them are involved in protein synthesis. Transfer RNAs (tRNAs) are the smallest RNAs (80-100 nucleotides). They bind amino acids and transport them to the site of protein synthesis. Messenger RNA (i-RNA) - they are 10 times larger than tRNA. Their function is to transfer information about the structure of the protein from DNA to the site of protein synthesis. Ribosomal RNA (r-RNA) - have the largest molecular size (3-5 thousand nucleotides) and are part of ribosomes.
Biological role of i-RNA i-RNA, being a copy from a certain section of a DNA molecule, contains information about the primary structure of one protein. A sequence of three nucleotides (triplet or codon) in an mRNA molecule (primary principle - DNA!) encodes a specific type of amino acid. A relatively small mRNA molecule transfers this information from the nucleus, passing through pores in the nuclear envelope, to the ribosome, the site of protein synthesis. Therefore, mRNA is sometimes called “template”, emphasizing its role in this process. The genetic code was deciphered in 1965-1967, for which H. G. Koran was awarded the Nobel Prize.
Ribosomal RNA Ribosomal RNA is synthesized mainly in the nucleolus and makes up approximately 85-90% of all RNA in the cell. In complex with proteins, they form part of ribosomes and carry out the synthesis of peptide bonds between amino acid units during protein biosynthesis. Figuratively speaking, a ribosome is a molecular computing machine that translates texts from the nucleotide language of DNA and RNA into the amino acid language of proteins.
Transfer RNAs RNAs that deliver amino acids to the ribosome during protein synthesis are called transport RNAs. These small molecules, shaped like a clover leaf, carry a sequence of three nucleotides at their top. With their help, t-RNAs will join the codons of i-RNA according to the principle of complementarity. The opposite end of the tRNA molecule attaches an amino acid, and only a certain type that corresponds to its anticodon
Genetic code Hereditary information is recorded in NK molecules in the form of a sequence of nucleotides. Certain sections of the DNA and RNA molecule (in viruses and phages) contain information about the primary structure of one protein and are called genes. 1 gene = 1 protein molecule Therefore, the hereditary information contained in DNA is called genetic.
Properties of the genetic code: Universality Discreteness (code triplets are read from the entire RNA molecule) Specificity (codon encodes only AK) Code redundancy (several)
Characteristics of DNA RNA SIMILARITIES Polynucleotides whose monomers have a common structural plan. DIFFERENCES: 1) Sugar deoxyribose ribose 2) Nitrogen bases adenine - thymine, cytosine - guanine adenine - uracil, cytosine - guanine 3) Structure double helix single-chain molecule 4) Location in the cell nucleus, mitochondria and chloroplasts cytoplasm, ribosomes 5) Biological functions storage hereditary information and its transmission from generation to generation; participation in matrix protein biosynthesis on the ribosome, i.e. implementation of hereditary information Checking the correctness of filling out the table
Biological significance of nucleic acids Nucleic acids ensure the storage of hereditary information in the form of a genetic code, its transmission during reproduction to daughter organisms, its implementation during the growth and development of the organism throughout life in the form of participation in a very important process - protein biosynthesis.
Final testing 1. DNA molecules represent the material basis of heredity, since they encode information about the structure of molecules a - polysaccharides b - proteins c - lipids d - amino acids 2. Nucleic acids do NOT contain a - nitrogenous bases b - pentose residues c – phosphoric acid residues d – amino acids 3. The bond that occurs between the nitrogenous bases of two complementary DNA chains, - a – ionic b – peptide c – hydrogen d – ester 4. Complementary bases are NOT a pair a – thymine - adenine b – cytosine - guanine c – cytosine - adenine d – uracil - adenine 5. One of the DNA genes contains 100 nucleotides with thymine, which is 10% of the total. How many nucleotides are there with guanine? a – 200 b – 400 c – 1000 g – 1800 6. RNA molecules, unlike DNA, contain a nitrogenous base a – uracil b – adenine c – guanine d – cytosine
Final testing 7. Thanks to DNA replication a – the organism’s adaptability to its environment is formed b – modifications occur in individuals of the species c – new combinations of genes appear d – hereditary information is fully transmitted from the mother cell to the daughter cells during mitosis 8. mRNA molecules a – serve as a template for the synthesis of t-RNA b – serve as a template for protein synthesis c – deliver amino acids to the ribosome d – store the hereditary information of the cell 9. The code triplet AAT in the DNA molecule corresponds to the triplet in the i-RNA molecule a – UUA b – TTA c – HGC g – CCA 10. Protein consists of 50 amino acid units. The number of nucleotides in the gene in which the primary structure of this protein is encrypted is a – 50 b – 100 c – 150 g – 250
Final testing 11. In the ribosome, during protein biosynthesis, there are two triplets of mRNA, to which, in accordance with the principle of complementarity, anticodons are attached a - t-RNA b - r-RNA c - DNA d - protein 12. Which sequence correctly reflects the path of implementation of genetic information? a) gene – DNA – trait – protein b) trait – protein – i-RNA – gene – DNA c) i-RNA – gene – protein – trait d) gene – i-RNA – protein – trait 13. Own DNA and RNA in a eukaryotic cell contain a – ribosomes b – lysosomes c – vacuoles d – mitochondria 14. Chromosomes include a – RNA and lipids b – proteins and DNA c – ATP and t-RNA d – ATP and glucose 15. Scientists who suggested and proved that the DNA molecule is a double helix, it is a - I. F. Miescher and O. Avery b - M. Nirenberg and J. Mattei c - J. D. Watson and F. Crick d - R. Franklin and M. Wilkins
Completing the complementarity task Complementarity is the mutual complementation of nitrogenous bases in a DNA molecule. Task: a fragment of a DNA chain has the nucleotide sequence: G T C C A C G A A Construct the 2nd DNA strand using the principle of complementarity. SOLUTION: 1st strand of DNA: G-T-C-C-A-C-G-A-A. C-A-G-G-T-G-C-T-T The meaning of complementarity: Thanks to it, matrix synthesis reactions and self-duplication of DNA occur, which underlies the growth and reproduction of organisms.
Repetition and consolidation of knowledge: Insert the necessary words: RNA contains sugar... DNA contains nitrogenous bases...; Both DNA and RNA contain...; There is no nitrogenous base in DNA... The structure of the RNA molecule in the form of... DNA in cells can be found in... Functions of RNA:... RNA contains nitrogenous bases...; DNA contains sugar...; There is no nitrogenous base in RNA... The structure of the DNA molecule in the form... The monomers of DNA and RNA are...; RNA in cells can be found in... Functions of DNA:... (ribose) (A, G, C, T) (A, G, C, sugar, F) (U) (Nucleotide chains) (In the nucleus, mitochondria, chloroplasts) ( Participation in protein synthesis) A, G, C, (U) (deoxyribose) (T) (Double helix) (Nucleotides) (In the nucleus, cytoplasm, mitochondria, chloroplasts) (Storage and transmission of hereditary information)
Check yourself - the correct answers B D B C B A G B B A V A G G C
Conclusions Nucleic acids: DNA and RNA DNA is a polymer. Monomer - nucleotide. DNA molecules are species specific. The DNA molecule is a double helix, supported by hydrogen bonds. DNA chains are built according to the principle of complementarity. The DNA content in a cell is constant. The function of DNA is the storage and transmission of hereditary information.
Sources of information used Kamensky A. A., Kriksunov E. A., Pasechnik V. V. - Textbook General biology grades 10-11 - M.: Bustard, 2006 Mamontov S. G., Zakharov V. B. - General biology: textbook – M.: Higher School, 1986 Babiy T.M., Belikova S.N. – Nucleic acids and ATP // “I’m going to class” // M.: “First of September”, 2003 Unified State Examination 2011 Biology // Educational and training materials for preparing students./ G. S. Kalinova, A. N. Myagkova, V. Z. Reznikova. – M.: Intellect-Center, 2007
Questions for control
- What are carbohydrates?
- What groups are carbohydrates divided into?
- What properties do carbohydrates have?
- What functions do carbohydrates perform?
- What are lipids?
- What groups are lipids divided into?
- What functions do lipids perform?
- What properties do lipids have?
DNA and RNA -
nucleic
acids
Uniqueness of protein functions
Are there other substances that perform the same functions?
REGULATORS
ENZYMES
Other hormones, c-AMP, ions
RNA – ribozymes
PROTEINS
BUILDING
MATERIAL
PROTECTION
Carbohydrates, lipids
Matrices?
MOVEMENT
TRANSPORT
tRNA
Proteins perform all functions, except for one -
INFORMATIONAL
incapable of self-reproduction
This function is performed by DNA
its main and only function
- DNA - the biggest molecule in a cell. It is much larger than proteins and RNA
- Each chromosome = one DNA molecule
- 23 human chromosomes = 23 DNA molecules
- The longest of them are ≈ 8 cm
- DNA is molecule-text. The sequence of its nucleotides is written the entire hereditary program of the body
1 DNA molecule
another gene
chromosome
chromosomes in the nucleus
cell
DNA structure discovered
Date of Birth
molecular biology
Francis Creek
James Watson
Francis Harry Compton Crick
James Dewey Watson
Nobel Prize 1962
X-ray structural portrait of DNA - famous photo 51
Rosalind Franklin
1920 - 1958
DNA and RNA molecules can be seen with an electron microscope
DNA bacterial plasmids
Reovirus DNA
scanning electric microscope
DNA isolated
from one human chromosome
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/Laemmli.gif
DNA and RNA – irregular polymers
monomer – nucleotide
consists of 3 parts
3. nitrogenous base
2. phosphate
1. sugar
Same part
Ribose
deoxy ribose
Phosphate
Nitrogen base
Next nucleotide in the chain
Nucleotide
Nitrogen base – one of 4
phosphate
Sugar (ribose/deoxyribose)
Adenin, A
Guanin, G
Purines
Pyrimidines
Cytosine, C
Adenin, A
Guanin, G
Purines
Pyrimidines
Removed the methyl group
Cytosine, C
Uracil, U
1950 Chargaff rules
Erwin Chargaff
Chargaff rules
[ A ] + [ G ] = [ T ] + [ C ] = 50%
Chargaff's rules were explained by Watson and Crick
DNA is 2 chains connected according to the principle complementarity
Principle of complementarity:
- - - - - -
- - - - - -
More durable
Weak hydrogen bonds!
Principles of DNA structure
Irregularity
5 "
3 "
Double-stranded
Complementarity
Antiparallelism
3 "
5 "
What features in the structure of DNA directly indicate its function?
(Compare with the structure of proteins)
Differences between RNA and DNA
- Single-stranded molecules
- Sugar - ribose instead of deoxyribose
- U instead of T
- Much less– comparable in size to squirrels.
Types of RNA
- mRNA= messenger RNA, template
up to 10 thousand nucleotides
- t-RNA transport
about 100 nucleotides
- rRNA ribosomal
2-3 thousand nucleotides
linear
like proteins, they have
3-dimensional conformation
Formation of RNA secondary structure
Scheme of loop formation in RNA
due to complementary regions
Transfer RNA
~100 nucleotides
"clover leaf"
Ribosomal RNA
The largest of all types of RNA -
2-3 thousand nucleotides
16 S rRNA
Functions of RNA in the order they were opened
- Informational: implementation of information
All types of RNA are intermediaries in the transfer of information from DNA to protein
The meeting place of all three RNAs is ?
ribosome
Functions of RNA in the order they were opened
- Informational: storing information (for some viruses)
- Approximately 80% of human and animal viruses use RNA to record information
- In them, it performs the same role as DNA in all other organisms.
Functions of RNA in the order they were opened
- Catalytic 1982
Ribozymes – RNA enzymes
Not all RNAs, but only some:
rRNA ribosomes,
RNA of some viruses
RNA in the spliceosome
Image address http://commons.wikimedia.org/wiki/Image:Minimal_hammerhead_ribozyme_structure.png
Thomas Check
Minimal ribozyme capable of cleaving RNA
Functions of RNA in the order they were opened
- Regulatory 1990s
Small RNAs regulate gene function in the nucleus and protein synthesis in the cytoplasm
Similar to the function of DNA-binding proteins
RNA combines properties
- DNA– the principle of complementarity, allowing matrix copying of the molecule
- Belkov– a three-dimensional structure that allows you to perform a variety of functions (catalysis, regulation, transport)
Matrix copying
3-D shape and varied functions
Protein
This is not the end
but just the beginning
Description of the presentation by individual slides:
1 slide
Slide description:
2 slide
Slide description:
“NUCLEIC ACIDS” Lesson topic: Lesson goal: To characterize the structural features of nucleic acid molecules as biopolymers To reveal the mechanism of DNA doubling, the role of this mechanism in the transmission of hereditary information To learn to understand the essence of the genetic code
3 slide
Slide description:
Her Majesty - DNA The Swiss doctor F. Miescher in 1871 isolated nuclein from the white blood cells of patients. This word is derived from the Latin “nux” - the kernel of a nut, and the ending “-in” implied that it contains nitrogen, like proteins. Guanine, first isolated in 1858 by A. Strecker from Peruvian guano - bird droppings, a valuable nitrogen fertilizer. Kossel isolated thymine and adenine from thymus gland cells. The Greeks called the gland “adena”, which meant “dense”, “hard”. The thymus is also called the thymus gland. This is how thymine got its name. A fourth compound was isolated from thymus gland cells. Since the Greek word for cell is “cytos,” it is called “cytosine.” In 1910, Kossel was awarded the Nobel Prize in Medicine for his discoveries.
4 slide
Slide description:
Ribose was first obtained synthetically by the German chemist E. Fischer, who was awarded the Nobel Prize in Chemistry in 1902 for his study of sugars. In 1909, F. Leuven managed to isolate ribose while studying nuclein. It took him another twenty years to isolate deoxyribose! C. M. McCarthy and K. McLeod proved that “deoxyribose-type acid” is responsible for transformation in the cell and wrote about this in an article published on February 4, 1944. This day can be considered the birthday of deoxyribonucleic acid (DNA) in the biological sense words. It became clear that the gene is DNA! In 1953, Watson and Crick proposed a model of the double-stranded DNA helix. In 1962, Watson, Crick and Wilkins were awarded the Nobel Prize in Medicine for their discovery. R. Franklin, unfortunately, had died of cancer by this time. If this had not happened, then for the first time in the history of the Nobel Prizes it would have to be given to four... Her Majesty - DNA J. Watson
5 slide
Slide description:
BIOPOLYMER STRUCTURE OF DNA phosphodiester bridge between the nucleotides of the base hydrogen bond polynucleotide Nucleotide - phosphorus ester of the nucleoside. A nucleoside contains two components: a monosaccharide (ribose or deoxyribose) and a nitrogenous base. 3" end 5" end 3" end 5" end sugar phosphate backbone
6 slide
Slide description:
BIOPOLYMER STRUCTURE of RNA hydrogen bonds sugar-phosphate backbone of t-RNA base Monomers - RNA ribonucleotides - form a polymer chain by forming phosphodiester bridges between sugar residues.
7 slide
Slide description:
DNA RNA All DNA, regardless of its origin, contains the same number of purine and pyrimidine bases. Consequently, in any DNA there is one pyrimidine nucleotide for every purine nucleotide. A=T and G=C A+C=G+T RNA contains uracil – U instead of thymine.
8 slide
Slide description:
Independent work Compare DNA and RNA Signs of comparison: Location in the cell Structure of the macromolecule Monomers Composition of nucleotides Functions
Slide 9
Slide description:
DNA performs the following functions: storage of hereditary information occurs with the help of histones. The DNA molecule folds, first forming a nucleosome, and then heterochromatin, which makes up chromosomes; transmission of hereditary material occurs through DNA replication; implementation of hereditary information in the process of protein synthesis
10 slide
Slide description:
Multifunctionality of RNA Genetic replicative function. The function is realized during viral infections, reduplication of genetic material. Coding function. In RNA, the same triplets of nucleotides encode 20 amino acids of proteins, and the sequence of triplets in a nucleic acid chain is a program for the sequential arrangement of 20 types of amino acids in the polypeptide chain of a protein. Structure-forming function. Compactly folded small RNA molecules are similar to the three-dimensional structures of globular proteins, while longer RNA molecules form large particles or their nuclei. Recognition function. The recognition function is the basis of specific catalysis. Catalytic function (ribozymes). RNA is capable of performing the functions of both polymers fundamentally important for life - DNA and proteins.
11 slide
Slide description:
DNA REPLICATION Continuity of genetic material is ensured by complementarity, semi-conservativeness (contains part of the maternal helix unchanged), antiparallelism (3'-5'), discontinuity, i.e. replication process. Arthur Kornberg (1959) discovered the enzyme DNA polymerase.
12 slide
Slide description:
DNA REPLICATION Participation of enzymes: ligase connects short, newly synthesized fragment sections Okazaki polymerase attaches nucleotides in the 5 3 direction helicase unwinds the double helix, breaking hydrogen bonds primase is necessary for the synthesis of enzymes Okazaki as a seed (primer) Replicon - the area between two points at which synthesis begins "daughter" chains. Okazaki fragments are newly synthesized regions on the second DNA template strand.
Slide 13
Slide description:
Scientists have proposed various units of measurement to represent the amount of data associated with a person's genetic makeup. There is so much information recorded in DNA that if you transfer it into books and stack these books one on top of the other, their height will be 70 meters. Scientists have calculated that if you try to handwrite or print a person's gene map, and if the one who writes does it at a speed of 60 words per minute and works 8 hours a day, then it will take him 50 years to do this. In addition, the information stored in DNA can fill approximately 200 phone books of 500 pages each.
Slide 14
Slide description:
GENETIC CODE The code is triplet. The code is degenerate - each amino acid is encrypted by more than one codon. The code is unambiguous. Each codon encodes only one amino acid. There are “punctuation marks” between genes; there are none inside the gene. The code is universal. The genetic code is the same for everyone living on Earth
15 slide
Presentation on the topic: “RNA and DNA. Their structure and functions." Prepared by: Voronina Ekaterina Prepared by: Voronina Ekaterina Peteshova Alexandra, student of 9 “a” class GOUCE 1865 Peteshova Alexandra student of 9 “a” class GOUCE 1865 Scientific supervisor: Stepanova Svetlana Yuryevna. Moscow 2008
Introduction. Introduction. Types and distribution of DNA and RNA. Types and distribution of DNA and RNA. General properties of acids. General properties of acids. Chemical structure. Chemical structure. Three-dimensional structure of DNA. Three-dimensional structure of DNA. DNA double helix. DNA double helix. Function of nucleic acids. Function of nucleic acids. Replication and transcription. Replication and transcription. Translation of nucleic acids into proteins. Translation of nucleic acids into proteins. Conclusion. Conclusion.
Nucleic acids are biopolymers consisting of phosphoric acid residues, sugars and nitrogenous bases (purines and pyrimidines). They have fundamental biological significance, since they contain in encoded form all the genetic information of any living organism, from humans to bacteria and viruses, transmitted from one generation to another. Nucleic acids are biopolymers consisting of phosphoric acid residues, sugars and nitrogenous bases (purines and pyrimidines). They have fundamental biological significance, since they contain in encoded form all the genetic information of any living organism, from humans to bacteria and viruses, transmitted from one generation to another.
As we have already said, there are two types of nucleic acids: DNA and RNA. DNA is present in the nuclei of all plant and animal cells, where it is complexed with proteins and is an integral part of chromosomes. In individuals of each specific species, the content of nuclear DNA is usually the same in all cells, except for gametes (eggs and sperm), where DNA is half as much. Thus, the amount of cellular DNA is species specific. DNA is also found outside the nucleus: in mitochondria (the “energy stations” of cells) and in chloroplasts (particles where photosynthesis occurs in plant cells). As we have already said, there are two types of nucleic acids: DNA and RNA. DNA is present in the nuclei of all plant and animal cells, where it is complexed with proteins and is an integral part of chromosomes. In individuals of each specific species, the content of nuclear DNA is usually the same in all cells, except for gametes (eggs and sperm), where DNA is half as much. Thus, the amount of cellular DNA is species specific. DNA is also found outside the nucleus: in mitochondria (the “energy stations” of cells) and in chloroplasts (particles where photosynthesis occurs in plant cells).
A certain amount of RNA is present in the cell nucleus, but the bulk of it is in the cytoplasm - the liquid content of the cell. Most of it is ribosomal RNA (rRNA). Ribosomes are the smallest bodies on which protein synthesis occurs. A small amount of RNA is represented by transfer RNA (tRNA), which is also involved in protein synthesis. However, both of these classes of RNA do not carry information about the structure of proteins - such information is contained in matrix, or information, RNA (mRNA), which accounts for only a small part of the total cellular RNA. A certain amount of RNA is present in the cell nucleus, but the bulk of it is located in cytoplasm - the liquid contents of the cell. Most of it is ribosomal RNA (rRNA). Ribosomes are the smallest bodies on which protein synthesis occurs. A small amount of RNA is represented by transfer RNA (tRNA), which is also involved in protein synthesis. However, both of these classes of RNA do not carry information about the structure of proteins - such information is contained in matrix, or information, RNA (mRNA), which accounts for only a small part of the total cellular RNA
Nucleic acid molecules contain many negatively charged phosphate groups and form complexes with metal ions; their potassium and sodium salts are highly soluble in water. Concentrated solutions of nucleic acids are very viscous and slightly opalescent, and in solid form these substances are white. Nucleic acids strongly absorb ultraviolet light, and this property underlies the determination of their concentration. The mutagenic effect of ultraviolet light is also associated with this property. Nucleic acid molecules contain many negatively charged phosphate groups and form complexes with metal ions; their potassium and sodium salts are highly soluble in water. Concentrated solutions of nucleic acids are very viscous and slightly opalescent, and in solid form these substances are white. Nucleic acids strongly absorb ultraviolet light, and this property underlies the determination of their concentration. The mutagenic effect of ultraviolet light is also associated with this property. Long DNA molecules are fragile and break easily, for example when forcing a solution through a syringe. Therefore, working with high molecular weight DNA requires special care. Long DNA molecules are fragile and break easily, for example when forcing a solution through a syringe. Therefore, working with high molecular weight DNA requires special care.
Nucleic acids are long chains consisting of four repeating units (nucleotides). Their structure can be represented as follows: Nucleic acids are long chains consisting of four repeating units (nucleotides). Their structure can be represented as follows:
The symbol F represents a phosphate group. Alternating sugar and phosphoric acid residues form the sugar-phosphate backbone of the molecule, which is the same for all DNA, and their enormous diversity is due to the fact that the four nitrogenous bases can be located along the chain in very different sequences. The symbol F represents a phosphate group. Alternating sugar and phosphoric acid residues form the sugar-phosphate backbone of the molecule, which is the same for all DNA, and their enormous diversity is due to the fact that the four nitrogenous bases can be located along the chain in very different sequences.
Nitrogen bases are planar heterocyclic compounds. They are attached to the pentose ring at position 1¢. The larger bases have two rings and are called purines: adenine (A) and guanine (G). The smaller bases have one ring and are called pyrimidines: these are cytosine (C), thymine (T) and uracil (U). DNA contains the bases A, G, T and C; RNA contains U instead of T. The latter differs from thymine in that it lacks a methyl group (CH3). Uracil is found in the DNA of some viruses, where it performs the same function as thymine. Nitrogen bases are planar heterocyclic compounds. They are attached to the pentose ring at position 1¢. The larger bases have two rings and are called purines: adenine (A) and guanine (G). The smaller bases have one ring and are called pyrimidines: these are cytosine (C), thymine (T) and uracil (U). DNA contains the bases A, G, T and C; RNA contains U instead of T. The latter differs from thymine in that it lacks a methyl group (CH3). Uracil is found in the DNA of some viruses, where it performs the same function as thymine.
An important feature of nucleic acids is the regularity of the spatial arrangement of their constituent atoms, established by X-ray diffraction. The DNA molecule consists of two oppositely directed chains (sometimes containing millions of nucleotides), held together by hydrogen bonds between the bases: An important feature of nucleic acids is the regularity of the spatial arrangement of their constituent atoms, established by X-ray diffraction. A DNA molecule consists of two opposing strands (sometimes containing millions of nucleotides) held together by hydrogen bonds between the bases:
Hydrogen bonds connecting the bases of opposite chains are classified as weak, but due to their abundance in the DNA molecule, they firmly stabilize its structure. However, if a DNA solution is heated to approximately 60° C, these bonds are broken and the chains diverge - DNA denaturation (melting) occurs. Both DNA strands are twisted in a spiral about an imaginary axis, as if they were wound on a cylinder. This structure is called a double helix. There are ten base pairs for each turn of the helix. Hydrogen bonds connecting the bases of opposite chains are classified as weak, but due to their abundance in the DNA molecule, they firmly stabilize its structure. However, if a DNA solution is heated to approximately 60° C, these bonds are broken and the chains diverge - DNA denaturation (melting) occurs. Both DNA strands are twisted in a spiral about an imaginary axis, as if they were wound on a cylinder. This structure is called a double helix. There are ten base pairs for each turn of the helix.
The structure of DNA resembles a spiral staircase. Its sides are composed of alternating sugar residues and phosphate groups; Each sugar residue in one sidewall is connected to its partner in the other by a “crossbar” consisting of a purine (adenine or guanine) and a pyrimidine (cytosine or thymine), with adenine connecting only to thymine and guanine to cytosine. The structure of DNA resembles a spiral staircase. Its sides are composed of alternating sugar residues and phosphate groups; Each sugar residue in one sidewall is connected to its partner in the other by a “crossbar” consisting of a purine (adenine or guanine) and a pyrimidine (cytosine or thymine), with adenine connecting only to thymine and guanine to cytosine.
One of the main functions of nucleic acids is to determine the synthesis of proteins. Information about the structure of proteins encoded in the nucleotide sequence of DNA must be transmitted from one generation to another, and therefore its error-free copying is necessary, i.e. synthesis of exactly the same DNA molecule (replication). One of the main functions of nucleic acids is to determine the synthesis of proteins. Information about the structure of proteins encoded in the nucleotide sequence of DNA must be transmitted from one generation to another, and therefore its error-free copying is necessary, i.e. synthesis of exactly the same DNA molecule (replication).
From a chemical point of view, nucleic acid synthesis is polymerization, i.e. sequential connection of building blocks. Nucleoside triphosphates serve as such blocks; the reaction can be represented as follows: From a chemical point of view, nucleic acid synthesis is polymerization, i.e. sequential connection of building blocks. Nucleoside triphosphates serve as such blocks; the reaction can be represented as follows:
Genetic information encoded in the nucleotide sequence of DNA is translated not only into the language of the nucleotide sequence of RNA, but also into the language of amino acids - monomeric units of proteins. Proteins contain 20 different amino acids, the sequence of which determines their nature and functions. This sequence is determined by the nucleotide sequence of the corresponding gene - the DNA section that encodes the protein. However, DNA itself is not the template for protein synthesis. First, it is transcribed in the nucleus to form messenger RNA (mRNA), which diffuses into the cytoplasm, and protein is synthesized on it as a template. The process is accelerated due to the fact that many protein molecules can be synthesized simultaneously on each mRNA molecule. Genetic information encoded in the nucleotide sequence of DNA is translated not only into the language of the nucleotide sequence of RNA, but also into the language of amino acids - monomeric units of proteins. Proteins contain 20 different amino acids, the sequence of which determines their nature and functions. This sequence is determined by the nucleotide sequence of the corresponding gene - the DNA section that encodes the protein. However, DNA itself is not the template for protein synthesis. First, it is transcribed in the nucleus to form messenger RNA (mRNA), which diffuses into the cytoplasm, and protein is synthesized on it as a matrix. The process is accelerated due to the fact that many protein molecules can be synthesized simultaneously on each mRNA molecule.
The sequence of bases in DNA determines the order of amino acids in a protein, since each amino acid is added by a specific enzyme only to certain tRNAs, and those, in turn, only to certain codons in the mRNA. The tRNA-amino acid complexes bind to the template one at a time. The main stages of protein synthesis are listed below (see also figure). The sequence of bases in DNA determines the order of amino acids in a protein, since each amino acid is added by a specific enzyme only to certain tRNAs, and those, in turn, only to certain codons in the mRNA. The tRNA-amino acid complexes bind to the template one at a time. The main stages of protein synthesis are listed below (see also figure).
Nucleic acids play a vital biological role in the cell: DNA molecules store hereditary information, and RNA molecules are involved in processes associated with the transfer of genetic information from DNA to protein. Nucleic acids play a vital biological role in the cell: DNA molecules store hereditary information, and RNA molecules are involved in processes associated with the transfer of genetic information from DNA to protein. Nucleic acids are essential components not only of all living cells, but also of viruses. Nucleic acids are essential components not only of all living cells, but also of viruses.
Goals and objectives of the lesson: to form a concept about nucleic acids; form a concept about nucleic acids; consider the structure and functions of nucleic acids; consider the structure and functions of nucleic acids; teach the ability to compare DNA and RNA; teach the ability to compare DNA and RNA; demonstrate techniques for using text when compiling a table; demonstrate techniques for using text when compiling a table; teach how to solve problems in molecular biology on the topic of DNA teach how to solve problems in molecular biology on the topic of DNA
Nucleic acids - from the Latin “nucleus” - nucleus. The Swiss physician Johann Friedrich Miescher in 1871 discovered a new substance, nuclein, in pus. He was only a Swiss doctor, Johann Friedrich Miescher, who discovered a new substance, nuclein, in pus in 1871. He was only 23 years old. 23 years old. His student Richard Altmann in 1889 renamed nuclein to nucleic acid His student Richard Altmann in 1889 renamed nuclein to nucleic acid
There are two types of nucleic acids There are two types of nucleic acids Deoxyribonucleic acid (DNA), which includes the carbohydrate - deoxyribose Deoxyribonucleic acid (DNA), which includes the carbohydrate - deoxyribose Ribonucleic acid (RNA), which includes the carbohydrate - ribose. Ribonucleic acid (RNA), which contains the carbohydrate ribose.
In 1962, the Nobel Prize for the discovery of the structure of the DNA molecule was awarded to: American biochemist James Watson American biochemist James Watson English scientist Francis Crick English scientist Francis Crick English biophysicist Maurice Wilkins English biophysicist Maurice Wilkins
Structure of DNA DNA is a double unbranched polymer folded into a spiral DNA is a double unbranched polymer folded into a spiral DNA is a biopolymer whose monomers are nucleotides DNA is a biopolymer whose monomers are nucleotides Each nucleotide consists of: Each nucleotide consists of: 1. a nitrogenous base - 1. nitrogenous base - adenine (A), cytosine (C), guanine (G) or thymine (T); adenine (A), cytosine (C), guanine (G) or thymine (T); 2. monosaccharide – deoxyribose; 2. monosaccharide – deoxyribose; 3. phosphoric acid residue 3. phosphoric acid residue
In the late 1940s, the Austrian-born American biochemist Erwin Chargaff found that all DNA contains equal numbers of T and A bases and, similarly, equal numbers of G and C bases. However, the relative content of T/A and G/C in a DNA molecule specific for each species.
Functions of DNA Storage of genetic information Storage of genetic information Transfer of genetic information from parents to offspring Transfer of genetic information from parents to offspring Implementation of genetic information in the process of life of a cell and organism Implementation of genetic information in the process of life of a cell and organism
Structure of RNA RNA is a biopolymer whose monomer is nucleotides RNA is a biopolymer whose monomer is nucleotides RNA is a single polynucleotide sequence. RNA viruses can be single- or double-stranded RNA - a single polynucleotide sequence. Virus RNA can be single- or double-stranded. Each nucleotide consists of: Each nucleotide consists of: 1. Nitrogen base A, G, C, U (uracil) 2. Monosaccharide - ribose 3. Phosphoric acid residue Types of RNA nucleotides: Adenyl, Guanylic, Cytidyl, Uridyl RNA Nucleotide Types: Adenyl, Guanylic, Cytidyl, Uridyl
Types of RNA. Transfer RNA (tRNA). tRNA molecules are the shortest. Transfer RNA is mainly found in the cytoplasm of the cell. The function is to transfer amino acids to ribosomes, to the site of protein synthesis. Of the total RNA content of a cell, t-RNA accounts for about 10%. Ribosomal RNA (r-RNA). These are the largest RNAs. Ribosomal RNA constitutes an essential part of the structure of the ribosome. Of the total RNA content in a cell, r-RNA accounts for about 90%. Messenger RNA (i-RNA), or messenger RNA (m-RNA). Contained in the nucleus and cytoplasm. Its function is to transfer information about the structure of the protein from DNA to the site of protein synthesis in ribosomes. mRNA accounts for approximately 0.51% of the total RNA content of the cell.
Problems in molecular biology 1. A section of one of the two chains of the DNA molecule contains 300 nucleotides with adenine (A), 300 nucleotides with adenine (A), 100 nucleotides with thymine (T), 100 nucleotides with thymine (T), 150 nucleotides with guanine (G), 150 nucleotides with guanine (G), 200 nucleotides with cytosine (C). 200 nucleotides with cytosine (C). How many nucleotides with A, T, G, C are contained in a double-stranded DNA molecule? Are A, T, G, C contained in a double-stranded DNA molecule?
Sources used V.V. Beekeeper "Biology" 9th grade, Moscow, "Bustard", 2011. V.V. Beekeeper "Biology" 9th grade, Moscow, "Bustard", 2011. V.V. Pasechnik “Thematic and lesson planning for the textbook”, M, “Drofa”, 2011. V.V. Pasechnik “Thematic and lesson planning for the textbook”, M, “Drofa”, 2011. Internet: Yandex - pictures Internet: Yandex - pictures
