Genetics Exam 3: Epigenetics

What is epigenetics

the study of the modifications of an organism’s genetic and phenotypic expression that are not attributable to alteration of DNA sequence

What is chromatin

a complex of DNA and proteins (primarily histones)

What are some chromatin functions

package DNA to fit in nucleus

provided important chromosomal architecture

protects integrity of chromosomes

permit faithfully segregation during mitosis and meiosis

serve as a mechanism for regulating gene expression

How can you alter epigenetics

with DNA methylation and histone modifications

T/F: epigenetic modifications are secondary regulators of cell specific functions

False, they are primary regulators

What are the 3 post-translational histone modifications

phosphorylation: addition of phosphate group w/ kinase

methylation: addition of a methyl group w/ methyltransferase

acetylation: addition of acetyl group w/ acetyltransferase

Which component in the histone tails can be modified

amino acids

How does chemical histone modification affect chromatin

alters the structure, making genes accessible or inaccessible for transcription

Which enzyme and modification opens the chromatin structure

Histone acetyltransferase with acetylation

What enzyme closes the chromatin structure and removes the acetyl group

histone deacetylase

Unmethylated DNA is considered __ and methylated DNA is considered __

on ; off

Where is the methyl group added?

on the 5’ position of cytosine

What is methylation catalyzed by

DNA methyltransferase

What makes up CpG dinucleotides and where are they found

cytosine adjacent to guanines

found in CpG islands

Where are CpG islands found

around promoter sequences that are adjacent to genes

How do methyl groups silence genes

by blocking the binding of transcription factors and other proteins necessary to form transcription complexes

When is someone more susceptible to epigenetic modifications?

fetal development

What is developmental programming

process through which a stimulus or insult establishes a permanent response

What is an epigenetics phenotype example

Mastitis + Holstein genetics

What do imprinted genes encode

growth factors or other growth-regulating genes

When would imprinting disorders originate?

during fetal growth & development

What is an example of an imprinting disorder

BWS