Chromatin Structure Part 2 Flashcards
1
Q
In a “normal” nucleosome
A
- DNA coils around the histone octomer in a left handed coil
- and negatively supercoiled (right handed supercoils)
2
Q
nucleosome core
A
- histone octomer
- 146 bp DNA
- 1 3/4 turns
- results from a limit digest of chromatin by micrococcal nuclease
3
Q
complete nucleosome
A
- contains 146 bp DNA + octomer (nucleosome core)
- spacer of ~54 bp DNA
- room enough for H1 histone to bind
- definition does not include H1
4
Q
linker DNA
A
- variable
- holds cores together
5
Q
linker histones
A
facilitates folding of 10 nm fiber (beads on a string) into 30 nm fiber
6
Q
chromatin containing H1
A
- nucleosomes with regular zigzag orientation
7
Q
no H1
A
- beads on a string
8
Q
nucleosome ladders
A
- microccal nuclease-generated nucleosome ladder of chromatin
- if chromatin was uniform you would get a smear of DNA
- provided evidence for particulate structure of chromatin.
9
Q
transgenic marker genes
A
- used to determine if piece of DNA has been successfully inserted into the genome of the host organism
- gene from one organism put into another
10
Q
selective markers
A
- genes that protect the transformed organism or cell from a selective agent (usually an antibiotic)
11
Q
screenable markers
A
- genes that give transformed cells an identifiable characteristic to distinguish them from untransformed cell
- do not confer resistance to a selective agent
12
Q
example of screenable markers
A
- GFP - fluoresces green when excited by UV light
- luciferase - enzyme that converts energy of ATP into light
- B-gal - convert colorless substrates into colored compounds that can be easily observed
- can be used as reporter genes
13
Q
reporter genes
A
- usually attached to regulatory sequences of another gene of interest to test the effects of the regulatory sequences
- products are readily quantifiable
- measure genes activity level
