Dna Organization And Cell Identity Flashcards
What is differentiation
Cells specialize into different cell types
What is chromatin closure associated with
Differentiation
What does the histone code help with
Organizing chromatin and regulating gene expression
What happens to the chromatin on genes when cells are more differentiated
The chromatin for other cells types close and only the specific cells type genes and general cell function genes are on
Stem cells are
Least differentiated
What is a niche
A thing the allows the cells to keep its identity as a stem cell
Highly specialized cells can’t act as
Stem cells
Gene control cell. _____ and chromatin controls cell _____
Identity
Differentiation
What are bookmarks
A combination of of epigenetic marks and protien partners
that leave instructions on the genes to allow the cell to come back to its original state once changed
Can bookmarks be reprogrammed and how
Yes by the micro environment
The micro environment can control developmental decisions and cell identity
What is heterochromatin
Euchromatin
Tightly packed after mitosis inactive
Loosely packed dispersed active after mitosis
What do chromosomes consist of
Histones
Chromatin fibres
Nucleosomes
What are chromatin fibres
What are histones
What are nucleosome
Fibres. made of dna and is a accosiated protiens that wraps around the histones
Highly conserved protiens
The repeating subunit of dna and histones
What is histone H1
The linker between the dna and histones
A chromsome has a _______
Single dna molecule
What is the core complex
How many times does dna wrap around it
The histone octamer
DNA wraps around this 1.2x
What is the core complex made of
2 of each
H2A
H2B
H3
H4
What is the role of the histones
They have a amino terminal tail that sticks out past the dna
Modification of these tails can change the nucleosomes identity
Histones, regulatory protiens and enzymes can help alter dna transcription, compactions, replication, recombination, and repair
What are epigenetic marks
Modifications to the histone tails
These can act as docking site to help non histone proteins park there
This can change the way that histones of nearby nucleosomes interact with the altered nucleosome
What epigenetic histone modifications occur
Phosphorylation
Acetylation
Methylation
Ubiquitination
What is the histone code hypothesis
The activity of a region of chromatin depends on the amount and specific type of chemical modification of the histone tails
What is another thing that can silence chromatin
Small rnas
They recruit protiens that modify the histones
What is dna methylation
Histone methylation
The 5th carbon of cytosine residues in dna get a methyl group added by dna methyl transferase
Histone methyl transferase add methyl’s (mono or di) to arg and lys residues of the histone protien
What part of a histone get actyleated
How
Lysine residues of histones
HAT (adds)
HDAC (removes)
