HMB265H1 Lecture Notes - Lecture 19: Earthbound, Dna Supercoil, Pleiotropy

• School: UTSG
• Department: Human Biology
• Course: HMB265H1
• Professor: Maria Papaconstantinou

Document Summary

Lecture 19 outline: definition of epigenetics, molecular mechanisms, examples, effect of diet, x-chromosome inactivation, parental imprinting. Examples of how the environment can change phenotype: x-chromosome inactivation connects with the barr body and discussion of chromosomal abnormalities with sex chromosomes. Identical twins easy to see how genotypes equate with phenotypes, with a 1:1 relationship: however, these two mice are also genetically identically (practically clones), yet they look very different fur colour and body weight. They both carry an allele of the agouti gene, which is responsible for the variability in phenotype, and the difference is due to an epigenetic change. Epigenetics plays a huge role in shaping organisms. But, these mice are genetical identical: all have genotype = avy/a, differences due to epigenetic changes. In vivo (i. e. , within the nuclei of living eukaryotic cells), dna molecules are found carefully packaged into structures known as chromosomes.