Epigenetics

What is Proportionate Heritability?

when an organisms phenotype is partly explained by genes and partly by environmental factors

How do environmental factors influence phenotype? (+example)

They modify the performance of proteins, not the level of gene expression itself. eg. tyrosinane is a heat-sensitive enzyme and is inactive at normal body temp. It becomes activated when exposed to low temp, causing it to produce melanin.

What are epigenetic modifications?

changes that affect how genes are turned on or off without changing the DNA sequence

What is translation?

mRNA instructs the ribosomes how to build the specific protein for which the DNA sequence codes

What is transcription?

involves reading and copying out a gene sequence from a DNA molecule

How do Epigenetics work?

molecules increase or decrease the amount of transcription of a particular gene, which alters the amount of protein that is produced

What is DNA methylation?

methyl groups attach to certain nucleotides and generally silence them

What is DNA demethylation?

removal of methyl groups from a DNA sequence that leads to a gene being expressed

What is Histone Modification?

When HMT joins methyl groups and modifies how tightly DNA is being wrapped around it. If it is tighter it is more difficult for genes to be transcribed and expresses. If less tightly packed the genes are easier to transcribe and express