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Organization of mammalian genome
1. DNA is packaged into nucleosomes by winding around histone proteins. This beads-on-a-string structure further condenses into the 30nm chromatin fiber. 2. Chromatin fiber is packaged into either loosely packed euchromatin, which contains actively transcribed genes, or tightly packed heterochromatin, which contains mostly repetitive sequences. 3. During cell division, chromatin maximally condenses into chromosomes, with two arms separated by a centromere and capped by telomeres at either end. This allows for orderly separation of genetic material during cell division.
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Organization of mammalian genome
- 1. CatabolismofHeme BY VANA JAGAN MOHANRAO M.S.Pharm, MED.CHEM NIPER,KOLKATA Asst. Professor, MIPER- KURNOOL Email: [email protected]
- 3. What are thedifferences between DNA and RNA? DNA RNA Sugar deoxyribose ribose Bases A, G, C, T A, G, C, U Strands Double strands Single strand Genetic material Most life Some viruses Enzymatic None Many with Structure Double helix Linear or folded
- 4. DNA structural forms A-DNA: •11bp/turn. • Diameter 2.2 nm. • Right handed double helix. • Short and wide. • Found in low humidity.
- 5. Z-DNA: • 12bp/turn. • Diameter1.8nm. • Left handed double helix. • Thin and elongated. DNA structural forms
- 6. B-DNA: • 10bp/turn. • Diameter2nm. • Right handed double helix. • High humidity conditions • The one found in the cell! DNA structural forms
- 7. Genome organization The characteristicsof the genomes of different life forms Viruses Prokaryotes Eukaryotes
- 8. What is agenome? The entire genetic code of an organism How is the genetic code organized? Thousands / millions/ billions of nucleotide basepairs How? Genome organization
- 9. Viral genomes • Genomecan be: 1. single stranded DNA. 2. double stranded DNA. 3. single stranded RNA. 4. double stranded RNA. • Genome can be linear or circular.
- 10. •One molecule orsegmented genome (many pieces). •Viruses with RNA genome are called retroviruses! •Genome size 2 thousand basepairs (2Kb) – 2 million basepairs (2 Mb). •No special organization of the genome. Viral genomes
- 11. Prokaryotic genomes • Mostgenomes are: 1. single molecule. 2. one circular chromosome. 3. double stranded DNA. 4.some have small additional circular DNA that can replicate independently (plasmid). •Genome is organized in a structure called (Nucleoid).
- 12. • The genomeis loose and not surrounded by a membrane (different than eukaryotes). • Loop domain in bacterial genome contribute to the packaging. • Tofit the genome in a bacterial cell the DNA undergoes supercoiling. Prokaryotic genomes
- 13.
- 14. Prokaryotic genomes organization Prokaryotegenome organization through: 1.Nucleoid (protein DNA interaction). 2.Supercoiling. 3.DNA loops
- 15. Relaxed circular chromosome Supercoiled circular chromosome Prokaryoticgenomes organization
- 16. Eukaryotic genomes Where iseukaryotic genome located? Nuclear genome, mitochondrial genome, chloroplast genome
- 17. • Genomes are: 1.Genome is a double stranded DNA. 2.Genome arranged in several linear packages called chromosomes through interactions with several proteins. Eukaryotic genomes
- 18. •The chromosomes intheir most condensed form are called metaphase chromosomes. •The entire genome represented by metaphase chromosomes is called karyotype. •The number of sets of chromosomes in a given eukaryotic cell is referred to as the level of ploidy. What is your level of ploidy? Eukaryotic genomes
- 19. The genome packagedinto chromosomes Karyotype
- 20. Ploidy • Haploid (1N):cells that contain one set of chromosomes. Which of human cells are haploid and what 1N = ? • Diploid (2N): cells that contain two sets of chromosomes. Which of human cells are haploid and what 2N = ?
- 21. Measurement of Eukaryoticgenome sizes •Eukaryotic genome size are measured by the total amount of DNA found in a haploid genome and that is due to the level of ploidy exhibited by such organisms. • The size of a haploid genome is called the C-value.
- 22.
- 23. 1. Double strandedDNA + histones • DNA interacts with histone proteins to form Nucleosomes. •A histone octamer (H2A, H2B, H3, H4) x 2 interacts with DNA to form a nucleosome. •147 bp of DNA goes around each histone octamer around 1.65 times.
- 24. •Between two nucleosomes thereis a linker DNA that is ~ 40-50 bp. •This structure is referred to as beads-on-a-string. •Another histone protein (H1) also facilitate into further condensation. 1. Double stranded DNA + histones
- 25. 1. Double strandedDNA + histones
- 26. •Nucleosomes condense toform the Solenoid or the 30nm fiber. 2. Nucleosomes to chromatin fiber
- 27. • Nucleosomes condensein a spiral orientation. •As the name indicates the width of the molecule is 30nm. 2. Nucleosomes to chromatin fiber
- 28. • Chromatin packsinto: • Euchromatin • Heterochromatin. 3. Chromatin to Euchromatin and Heterochromatin
- 29. •Euchromatin: regions thatcondense and decondense during the cell cycle and normally represent active (loosely packed) regions because: • The regions are transcribed •The regions do not have a lot of repeat sequences. •Heterochromatin: regions that is condensed throughout the cell cycle. •These regions do not have genes or have genes that are not transcribed. 3. Chromatin to Euchromatin and Heterochromatin
- 30. The genome inits most condensed form is represented by chromosomes. 4. Chromosome formation
- 31. • Metaphase chromosomeshave: 1.Two arms (short p, long q) and separated by centromere. 2. Centromere (region holds the arms). 3. telomeres (ends of the chromosome). 4. Chromosome formation
- 32. Review of genomecondensation