BIO 321 Lecture Notes - Lecture 5: Chromosome, Transfer Rna, Methionine
Document Summary
Most new mutations, if recessive, and on autosomes, are lost. Initial frequency = 1/2n (n = population size) But if on the x are expressed in males. Most mutations are deleterious => stronger purifying selection on x in males. Mrna - a co(cid:510)ple(cid:510)e(cid:511)t o(cid:479) the 3"-5" dna stra(cid:511)d. Methionine transfer rna brings the methionine amino acid to the ribosome and the polypeptide strand is initiated (or elongated if this is in the middle of the polypeptide sequence) Most gene products work in pathways and/or networks. These networks result in the production of phenotypes (eg production of metabolic heat, storage of fats, etc) Genotype-phenotype relationship often depends critically on the environment. Physical exchange of material between homologous chromosomes. Occurs at the metaphase of first meiotic division. Recombination machinery- many of the same proteins/enzymes as dna repair machinery. Advantages of dna repair may have helped spur the evolution of meiosis/sexual reproduction. On average, one exchange per chromosome per meiosis.
