chromosome structure Flashcards
(25 cards)
Where is the DNA located?
chromosomes
what is chromatin made of?
DNA and protein
What are the types of interphase chromatin?
euchromatin and heterochromatin
what is euchromatin?
transcriptionally active DNA
what is heterochromatin?
inactive DNA
types of heterochromatin
constitutive and facultative
what is constitutive DNA
mostly repetitive, never expressed, near centromere
acrocentric chromosome
p arm barely seen
metacentric
centromere in middle
telocentric
centromere at end
submetacentric
short p arm long q arm
what is a karyotype?
the complete set of diploid chromosomes
geimsha staining
reveals g banding patterns and discriminates between chromosomes
what is the centromere made of?
highly repeated satellite DNA
What is satellite DNA?
repeating non coding DNA
Where is the telomere located?
at the ends of the chromosomes
function of telomere?
prevent degradation, maintains chromosomal integrity, molecular marker of ageing process
by how much is DNA condensed
by a factor of 10^5
what is the structural unit of DNA packing in eukaryotes
nucleosomes
what is a histone?
positively charged arginine or lysine rich proteins that joined together by ionic bonds with neg phosphate backbone
types of histone
H1. H2A. H2B. H3. H4.
how many histones form a nucleosome
8
number of base pairs in octamer
200
solenoid
6 nucleosomes per turn
