BIO-8 Lecture Notes - Lecture 17: Genetic Variation, Stabilizing Selection, Gene Pool
Document Summary
Evolution: galapagos islands, darwin"s finches, adaptive radiation, rapid evolution. As seed abundance decreased, the population fell. As seeds became harder, the average beak size increased. Section 1: the process of evolution depends on genetic variation. Deoxyribonucleic acid (dna): a molecule composed of two strands of nucleotides that are wound together into a double helix. Each strand is composed of subunits called nucleotides. Each nucleotide has a sugar, a phosphate group, and one of four nitrogenous bases: adenine (a), thymine (t), and cytosine (c), and guanine (g). The order of nitrogenous bases codes for genetic info. Chromosomes: compact structures consisting of long strands of dna would around proteins. Genes: are regions of dna that code for particular proteins; changes in some phenotypes are affected by a single allele (e. g. , blood type). Alleles: different forms of a particular gene. Changes in alleles can create differences in an organism"s phenotype.
