EE BIOL 185 Chapter Notes - Chapter 6.2: Influenza A Virus Subtype H5N1, Thymine, Nitrogenous Base
18 Feb 2017
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A small change to dna that is passed down across generations can have large effect on fitness: ex. A change to just one component of a single protein in the h5n1 virus makes this avian influenza virus more dangerous to mammalian hosts. Changes in dna sequences across populations and species are used to reconstruct phylogenetic relationships. Dna and chromosomes: dna is a polymer: macromolecule composed of repeating units linked together in a chain. 4 building blocks: adenine (a), guanine (g), cytosine (c), thymine (t) Each nucleotide is composed of pentose 5-carbon sugar deoxyribose, a phosphate group (phosphate and 4 oxygens), and nitrogen base. Cytosine/thymine = pyrimidines: dna is a double-stranded molecule each stra(cid:374)d has 5" e(cid:374)d (cid:449)ith ter(cid:373)i(cid:374)al phosphate group a(cid:374)d 3" e(cid:374)d (cid:449)ith ter(cid:373)i(cid:374)al h(cid:455)dro(cid:454)(cid:455)l group. Antiparallel fashion: oriented in opposite directions: first life on earth may have been rna-based. Reasons dna has replaced rna as genetic underpinning of life:
