Additional slides from lecture 13

Genetics: A Conceptual Approach

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DNA - composed of two strands: each a polymer of repeating nucleotides - nucleotide = sugar (deoxyribose) + phosphate + base (A,G,C,T) Two strands : - are wound around each other as a double helix - are antiparallel - are held together by hydrogen bonds between bases: A-T (2 H-bonds), G-C (3 H- bonds) - are complementary - can be denatured (higher %GC => higher T m ) - can be renatured
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RNA Key differences between RNA and DNA: DNA - Two polynucleotide strands - Sugar in nucleotides is deoxyribose - Bases: A, G, C, T - secondary structure: double helix RNA - One polynucleotide strand - Sugar in nucleotides is ribose - Bases: A, G, C, U - secondary structure: variable
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Chromosome Structure Prokaryotic - single circular DNA molecule Packing : - supercoiled loops held in place by non-histone proteins Eukaryotic - multiple linear DNA molecules per cell Packing : - series of higher order structures: i)nucleosome = DNA + core histones H2A, H2B, H3, H4 ii)chromatosome = nucleosome + histone H1 iii)30-nm fiber, plus several higher order fibers - degree of packing changes: i) during cell cycle: condensation before mitosis/meiosis ii) with gene expression: condensation of transcribed genes Special features : - centromeres - telomeres
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Eukaryotic Chromosome Structure Pair of homologous chromosomes Pair of homologous chromosomes S phase gene 1 gene 2 gene 3 gene 4 ( cv ) gene 5 ( f + ) gene 6 gene 1 gene 2 gene 3 ( f ) gene 5 gene 6 maternal paternal + gene 1 gene 2 gene 3 gene 4 ( cv ) gene 5
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This note was uploaded on 05/06/2010 for the course BIO 311 taught by Professor Otto during the Spring '10 term at George Mason.

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Additional slides from lecture 13 - DNA - composed of two...

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