Why Genome Organization is Required?
Efficient storage and functioning of genetic information.
Accessibility of genes for transcription and regulation.
Levels of DNA Packaging
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Nucleosome (DNA wrapped around histones).
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Chromatin fiber (stacked nucleosomes).
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Looped domains (300nm).
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Heterochromatin (700nm, inactive).
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DNA compaction.
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Metaphase chromosome (1400nm, mitosis/meiosis).
Levels of DNA Packaging
-
Nucleosome (DNA wrapped around histones).
-
Chromatin fiber (stacked nucleosomes).
-
Looped domains (300nm).
-
Heterochromatin (700nm, inactive).
-
DNA compaction.
-
Metaphase chromosome (1400nm, mitosis/meiosis).
Proteins in DNA Packaging
Histones, histone modifiers, and chromatin remodelers.
Nucleosome
Basic unit of DNA packaging.
DNA wrapped around histones.
Formation of Chromatin Fiber
Compact nucleosomes stack together.
Looped Domain Formation (300nm)
Chromatin loops on a protein scaffold.
Efficient gene regulation.
Formation of Heterochromatin (700nm)
Highly condensed and inactive chromatin.
Found near centromeres and telomeres.
DNA Compaction
Progressive compaction through multiple levels.
Formation of Metaphase Chromosome (1400nm)
Full condensation in mitosis/meiosis.
Chromosome
DNA and associated proteins.
Genes encode proteins and regulate processes.
Genome Organization in Viruses
Compact genomes due to small size.
Use capsids for genetic information protection.
Chromosome Parts
Centromere (segregation).
Telomeres (protection).
Chromatids
Types of Chromosomes
Autosomal (traits).
Sex chromosomes (determine sex).
Chromosome Function
Carry genetic information.
Genes instruct protein synthesis and regulation.
Accurate inheritance during cell division.
Bacterial Genome Organization
Single, circular chromosome.
Nucleoid region for organization.
DNA supercoiling (DNA gyrase, topoisomerases) and binding proteins for compaction.
Features of Bacterial Genome
Smaller size, essential genes.
May have plasmids with additional functions.
Genome Organization in Bacteria
Primarily organized in the nucleoid.
DNA supercoiling and protein binding for compaction.
Enzymes Associated with Supercoiling
DNA gyrase and topoisomerases regulate DNA supercoiling.
Chromosome Function and DNA Supercoiling
Influences gene regulation.
Affects gene accessibility for transcription.
Genome Organization in Eukaryotes
Larger genomes, linear chromosomes.
Enclosed within a nucleus.
Eukaryotic Genome
Coding and non-coding regions.
Introns (non-coding) and exons (coding).
