Genome organization

Genome organisation, chromosomes, Human genome project

1. Genome organization RIMA SINGH M.PHARM,1 ST YEAR Pharmacology I. s. F college of pharmacy under the guidance of DR. SIDHARTH MEHAN Associate professor DEPARTMENT OF PHARMACOLOGY 1

2. Contents Introduction Chromosome DNA Gene Gene Expression Genome Gene mapping and sequencing Human genome project Applications References 2

3. Introduction genome organization 3 Genome organization refers to the sequential organization of the entire genes. Genome

4. 4 Fig:1 Diagrammatic representation of chromosome, DNA, gene

5. Chromosome The term was coined by German scientists Schleiden , Virchow, Butschli . The DNA molecule is packaged into thread-like structures known as chromosomes. Each chromosome has a constriction point called the centromere, which divides the chromosome into two sections or arms. The short arm of the chromosome is labeled the ‘P’ arm and the long arm of the chromosome is labeled as the ‘Q’. Human chromosomes divided into two types: Autosomes and allosome, human cells have 23 pairs of chromosomes, or 46 chromosomes in total. 5

6. Chromosome numbers in different organisms 46 8 42 78 Human Fruit fly Monkey Chicken 6 38 Cat

7. 7 Fig: 2 DNA – Deoxyribonucleic acid

8. Gene Term was introduced by Danish Botanist, Wilhelm Johannsen in 1905. Gene is the sequence of DNA or RNA that codes for a molecule and it is the basic physical and functional unit of heredity. Some genes act as instructions to make molecules called proteins. Majority of organisms encode their genes in long strand of DNA. 8

9. Organization of gene Exons : Exons are the portion of gene sequence that codes for amino acids. Introns : Introns are the non-coding sequence which separate the coding sequence. TATA box : It directs important enzymes to the correct initiation site for transcription and present in the promoter region. Termination codon : The end of translation is signified by a termination codon . 9

10. Gene expression Gene expression is the process in which the instructions in our DNA are converted into a functional product, such as a protein. 10 Gene expression Specific information mRNA DNA Protein TRANSCRIPTION TRANSLATION (In nucleus ) (In Cytoplasm )

11. Fig: 3 Transcription, Translation 11

12. The Central Dogma The Central Dogma is an explanation of the flow of genetic information within a biological system. It stated that DNA makes RNA and RNA makes Protein. It was first stated by Francis Crick 1958 which states that once “information” has passed into protein it cannot get out again. 12

13. Genome A genome is the complete set of genetic information in an organism. It provides all of the information the organism requires to function. It consists complete set of DNA, including all of its genes. The term genome was created in 1920 by Hans Winkler. The name genome is the blend of the words gene and chromosome. The genome size is the total amount of DNA contained within one copy of a single genome. 13

14. Genomics Term Genomic was coined by Thomas H. Roderick in 1986. Genomic is the branch of molecular biology concerned with the structure, function, evolution and mapping of genome and sequences. 14

15. Gene mapping Gene mapping describes the methods used to identify the locus of a gene and the distances between genes. The essence of all genome mapping is to place a collection of molecular markers onto their respective positions on the genome. It is of two types: Genetic mapping Physical mapping 15

16. Gene mapping Genetic mapping Physical mapping 16 Arrangement of genes and genetic markers on a chromosome. Genetic markers are RFLP, VNTR etc. Provide physical distance between the gens located on a chromosome .

17. 17 Fig: 4 Gene Mapping

18. Why genome mapping is important Gene map is the anatomy of human genome. It is a prerequisite to understand functioning of human genome. Helps in analysis of the heterogeneity and segregation of human genetic diseases. Helps to develop methods for gene therapy. Provides clinically useful information about linkage. 18

19. Gene sequencing 19 It is the process of determining the precise order of nucleotides within a DNA molecule. It includes any method or technology that is used to determine the order of the four bases—adenine, guanine, cytosine, and thymine. This sequencing was first proposed by Frederick Sanger in 1975, by chain termination method or by dideoxy sequencing. Allan Maxam and Walter Gilbert developed the DNA sequencing method by chemical modification in 1976.

20. 20 Fig: 5 Gene sequencing

21. Why gene sequencing is important Genome sequencing is important to obtain a blue print where DNA directs all the instruction needed for cell development and function. To study gene expression in human tissue, organ. DNA underlines almost every aspect of human health, both in function and dysfunction. To study the human variations etc. 21

22. Human genome project Human Genome Project was an international scientific research project with the goal of determining the sequence of nucleotide base pairs that make up human DNA, and identifying and mapping all of the genes of the human genome. It was created by US government ( The Department of Energy). There are 3 billion base pairs present in human genome. Cost to sequence the first human genome was about $ 3 billion. And it took around 13 years to sequence the first human genome ( from 2000 – 2013 ). 22

23. Applications Improved diagnosis of disease. Earlier detection of predispositions to disease. Rational drug design. Gene therapy and control systems for drugs. Organ Replacement . Also useful in DNA forensics to identify potential suspects at crime scenes etc . 23

24. References Markus N; “Definition of historical models of gene and their relation to students’ understanding of genetics”; “Science and education”; 5 December 2006; 16(8): 849-881. Barnett L, Breoner S; “General nature of the genetic code for proteins” ; “Nature”; 1961; 192: 1227- 32. Woodson S A; “Ironing out the kinks: splicing and translation in bacteria”; “Genes and development”; may 1998; 12(9) : 1243-7. Albert B, Johnson A; “Molecular biology of the cell”; “Garland”; 14 July 2014; 6 th edition. Brosius J; “The fragmented gene”; “Annals of New York academy of science”; 2009: 186-193. 24

25. 25 THANKs FOR YOUR PATIENCE