L3

Question 1

DNA methylation and gene expression

Answer 1

Methylation prevents transcription because transcription factors can’t get to it - thus decreased gene expression

Question 2

Early life modifications to DNA methylation

Answer 2

• cellular/genetic
• stress
• food/nutrition
• maternal behaviour

Question 3

Genomic imprinting and examples

Answer 3

Silencing of one parental copy of each gene, depending on the sex of the parent from which it was inherited

eg timing of parturition denoted by paternally imprinted genes
placenta made by paternally imprinted genes

Question 4

X silencing

Answer 4

turn off expression of one copy of X chromosome in each cell to avoid producing double quantities - varies cell-to-cell whether it is maternal or paternal X that is silenced (CALICO CATS)

Question 5

Paternal diet effects on daughters

Answer 5

Paternal environmental expression can induce intergenerational transmission of impaired glucose-insulin homeostasis in female offspring

Question 6

Maternal depression

Answer 6

Increased methylation in foetal cord blood so decreased expression of glucocorticoid receptor gene and ths heightened infant stress response

Question 7

Imprinting genes

Answer 7

Genes that, when expressed in offspring, retain their identity regarding their parent of origin