Biology 3466B Lecture Notes - Phosphodiester Bond, Homologous Chromosome, Hemoglobin
Document Summary
Evolution lecture no. 1: origin of genetic variation i. The definition of evolution is the descent with change in allele frequencies. It is a concept that deals largely with populations and not necessarily with individuals; individuals develop, populations evolve. Within the field of evolution, genetic variation is rampant and it is one of the many distinct causes for consequences over evolutionary time. Evolution argues that mutation is a necessary phenomenon, in the sense that it is required to vary genes in populations. The nucleotide is the basic building block in the structure of dna containing the instructions for constructing an organism. Every dna nucleotide consists of 3 key components: a deoxyribose (5-carbon) sugar, a phosphate group and a nitrogenous base. There are 4 possible bases present in all dna structures: adenine, guanine, cytosine, and thymine. The first two bases, adenine and guanine, are known as purines as they both contain double-ring structures.