Exam 2: Genetic Regulation by Chromatin Structure Flashcards
all eukaryotes have their DNA packed by…
protein in chromosomes made of chromatin
fundamental unit of chromatin
nucleosome with its histone octamer core
2 functions of histone octamers
DNA packaging
gene regulation
histones are as important in gene regulation as…
transcription factors
do histones and TFs interact?
yes
how does DNA packing control gene expression?
genes can’t be expressed when they are wound tightly
2 ways histones help control chromatin structure
histone type switching
histone tail modification
protein tails are where…
modification occurs
HFD
histone fold domain where histones bind to each other
histone type switching
some histones have special alternative versions (varients)
switching to a different type of histone can have a big effect on the chromatin
macro-H2A
completely represses transcription
shuts down genes that make a stem cell able to differentiate
where is macro H2A found
heterochromatin near the centromere
inactivated x-chromosomes (barr body histone varient)
genes required for reprogramming cells
what happens if macro-H2A is removed from the genes that make a stem cell able to differentiate?
the cell becomes an induced stem cell
special feature of histone modification
have loose tails (n-terminal ends) that hang out of nucleosome
programmable by histone modification
modifications occur most often on the aa…
lysine, which is common in histone tails
