Moscow Lomonosov State University Biological Faculty M OLECULAR

Moscow Lomonosov State University Biological Faculty M OLECULAR G ENETICS DNA: The Genetic Material Genes and How They Work Control of Gene Expression Cellular Mechanisms of Development Altering the Genetic Message Gene Technology Presented by: Daria Molchanova Svirin Eugeny, group № 113

I NTRODUCTION What is molecular genetics? Why it is so called? Why it is necessary?

T HE G ENETIC MATERIAL DNA - is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. The main role of DNA - long-term storage of information about the structure of RNA and proteins. DNA - is a long polymer molecule composed of repeating units of nucleotides. Each nucleotide consists of nitrogenous bases, sugar and phosphate group.

S TRUCTUREOF DNA is a polymer. Monomer is a nucleotide. Each nucleotide consists of a phosphoric acid, sugar deoxyribose and one of four nitrogenous bases. Nucleotides are joined together into long polynucleotide chains. These chains are joined by hydrogen bonds in the double helix structure. Adenine Guanine Thymine Cytosine

H ISTORY OF DISCOVERY DNA was discovered by Misher in 1869. After the discovery scientists believed that DNA is a place of storage of phosphorus in the body. Then, in the forties of the twentieth century, it was proven that DNA is the carrier of genetic information James Watson And finally, in 1953, James Watson and Francis Crick proposed a model of the double helix. Francis Crick

G ENE Gene is structural and functional unit of heredity, which controls the development of a particular trait. Gene is a region of DNA, that carries information about the structure of a protein or a single RNA molecule. Each gene has a specific regulatory DNA sequences, which are directly involved in the regulation of gene expression.

B IOLOGICALFUNCTIONSOF DNA molecules are involved in two fundamental properties of living organisms - heredity and variation. Genetic information is realized with the gene expression in the processes of transcription (the synthesis of RNA) and translation (protein synthesis on the template RNA). A nucleotide sequence "encodes" information about the different types of RNA: matrix (m. RNA), ribosomal (r. RNA) and transport (t. RNA). All of them are synthesized on the basis of DNA during transcription.

T RANSCRIPTION Transcription is the process of creating a complementary copy of RNA from a sequence of DNA. Transcription contain 3 steps: Initiation, Elongation Termination. DNA RNA polymerase RNA

T RANSLATION In translation, RNA is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein. Diagram showing the translation of m. RNA and the synthesis of proteins by a ribosome.

R EPLICATION DNA replication is a biological process that occurs in all living organisms and copies their DNA; it is the basis for biological inheritance.

DNA AND PROTEINS All the functions of DNA depend on its interaction with proteins. These proteins can be divided into 2 groups: DNA-binding proteins DNA-modifying enzymes.

T RANSCRIPTIONAL REGULATION Regulation of transcription can be broken down into three main routes of influence: q genetic - direct interaction of a control factor with the gene q Modulation - interaction of a control factor with the transcription machinery) q Epigenetic - non-sequence changes in DNA structure which influence transcription. The lambda repressor transcription factor binds as a dimer to major groove of DNA target and disables initiation of transcription.

E PIGENETICMECHANISMS Eukaryotic cells can regulate transcription through modulation of nucleosome structure or modification of histone terminal chains, which are unbinded to DNA. Those modifications form a special epigenetic mechanism of regulation – “Histone code” Methylation of DNA causes gene inactivation and is also a widespread mechanism of expression regulation.

P OSTTRANSCRIPTIONAL MECHANISMS The nuclear membrane in eukaryotes allows further regulation of transcription factors by the duration of their presence in the nucleus.

S PLICING CAPPING & , POLYADENILATION

C ELL MIGRATIONAND INDUCTION Cells migrate by extending probes to neighboring cells which they use to pull themselves along. Interactions cells strongly influence the developmental paths they take. Signal molecules from an inducing cell alter patterns of transcription in cells which come incontact with it.

D ETERMINATION

P ROGRAMMEDCELL DEATH Animal development involves programmed cell death(apoptosis), in which particular genes, when activated, kill their cells. In the developing nematode two genes, ced-3 and ced-4, code for proteins that cause the programmed cell death of 131 specific cells. In the other cells, the product of a third gene, ced-9, represses the death program encoded by ced-3 and ced-4.

A LTERINGGENETICMESSAGE : MUTATIONS Rare changes in genes, called mutations, can have significant effects on the individual, when they occur in somatic tissue, but are only inherited if they occur in germ-line tissue. Inherited changes provide the raw material for evolution.

A LTERINGGENETICMESSAGE : RECOMBINATION Genetic recombination is a change in the genomic association among genes. It often involves a change in the position of a gene or portion of a gene. Recombination of this sort may result from oneway gene transfer or reciprocal gene exchange.

B IOTECHNOLOGYIN AGRICULTURE Herman the wonder bull Gen. Pharm, a California biotechnology company, engineered Herman, a bull that possesses the gene for human lactoferrin (HLF). HLF confers antibacterial and iron transport properties to humans. Many of Herman’s female offspring now produce milk containing HLF, and Gen. Pharm intends to build a herd of transgenic cows for the largescale commercial production of HLF.

W ILT-PROOF FLOWERS Ethylene, the plant hormone that causes fruit to ripen, also causes flowers to wilt. Researchers at Purdue have found the gene that makes flower petals respond to ethylene by wilting and replaced it with a gene insensitive to ethylene. The transgenic carnations they produced lasted for 3 weeks after cutting, while normal carnations last only 3 days.

B IOTECHNOLOGYIN MEDICINE Biotechnology allows us to manufacture large molecules, such as hormones, enzymes and etc. and use them as drugs. They are produced by applying genes to non-human organisms, like E. Coli.

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