ch 13 Flashcards
histones
small proteins with a lot of positive amino acids that can attack the DNA
nucleosome
DNA wrapped around 4 core histone proteins
what effect does a super condensed chromosomes have on transcription?
this process happens during cell division but does not allow for transcription to happen
FISH (Florence in situ hybridization):
allows researchers to find locations of specific DNA sequences with respect to the chromosome karyotype
SKY (Spectral karyotyping):
uses a mixture of DNA probes with various fluorescent tags to visually color code individual chromosomes.
what are the two types of regions that are stained to be seen under a microscope?
-Heterochromatin
-Euchromatin
Heterochromatin
-DNA is very tightly packed/condensed.
-does not allow for transcription since the DNA can not be opened up.
-if the gene is rearranged and placed near compact heterochromatin it can be silenced/shut off -> creates a mosiaic indiv
Euchromatin
what are the two kinds of chromosomal modifications?
Acetylation
Methylation
what is a Acetylation?
-adds an acetyl group to the histone tails (histone acety ltransferase HATs) that will loosen the chromatin and promote transcription
-.HDACs (histone deacetylase) will remove the acetyl group and reverse the entire process to create a closed chromatin and repress transcription.w
what happens when a histone complex has a high number of modifcations of acetyl groups?
DNA bound to the istone complex has actively transcribing genes.
Methylation
adds a CH3 grp to the histone tails so it tightens the chromatin and inhibits transcription or it can lose the chromatin and promote transcription either scenario depends on which Amino acid is methylated(hetro or eu).
why does x chromosome inactivation happen?
because of the supercondensing of the inactive X chromosome
