Epigenetics Flashcards
what do epigenetic effect
how accessible sections of DNA are
what happens if a section of a DNA is inaccessible
genes in that section are not transcribed so will not be expressed
how does DNA methylation modify the activation of certain genes
addition of methyl groups attach to DNA bases
stops enzyme RNA polymerase binding to DNA
gene is switched off and transcription cannot take place
no mRNA is formed
no protein made
gene not expressed
how does histone modification modify the activation of certain genes
addition of methyl or acetyl groups attach to histone tail
this effects how tightly the DNA winds around the histone proteins
Tightly-
gene is inaccessible
gene is switched off
cannot be transcribed so no mRNA is formed
no protein formed
gene is not expressed
Loosely-
gene is accessible
can be transcribed so mRNA is formed
protein formed
gene is expressed
what does the agouti gene in mice do to the phenotype if expressed
what is a female mouse with agouti gene capable of
mouse is yellow and obese
has the capability of having offspring where agouti gene is not expressed
what is the effect of diet (environment) on the phenotype of the offspring of a mother who expresses the agouti gene
mother who expresses agouti gene is fed a methyl rich diet during pregnancy
DNA methylation of the agouti gene occurs
gene is switched off
no transcription so no mRNA formed
agouti gene is not expressed
offspring makes melanin so is brown
does not overeat so is slim
what are the effects of behaviours of the mouse mothers on its offspring from good mothers were swapped to bad mothers and vice versa
good mother with bad mother offspring-
offsping had high glucorticoid levels (stress)
high licking and grooming from mother
means no methylation of GR gene in offspring
GR protein is made so binds to glucorticoid
means GR gene is expressed
so low anxiety in offspring
bad mother with good mother offspring-
offspring had high glucorticoid levels (stress)
low licking and grroming from mother
means methylation of GR gene in offspring
mean no GR receptor protein made
GR gene not expressed so glucorticoid levels remain high
so high anxiety in offspring
what does the GR gene produce in mice
receptor protein that binds to the stress hormone glucocorticoid
this stops the stress response causing the mouse to relax
what happens in mice when they are exposed to high levels of stress
(good mother with bad offspring)
high glucocorticoid levels
high licking and grooming from good mother
no methylation of GR gene in offspring
GR receptor protein is made so binds glucocorticoid
gene is expressed
low anxiety and high licking and grooming in mouse offspring
what happens in mice when they are exposed to high levels of stress
(bad mother with good offspring)
high glucocorticoid levels
low licking and grooming from bad mother
methylation of GR gene in offspring occurs
no GR receptor protein made so cannot bind to glucocorticoid
glucocorticoid levels remain high
gene is not expressed
high anxiety and low licking and grooming in mouse offspring
