DNA Packaging Flashcards
what is the total length of DNA strands contained in a single cell?
2.04 metres
define karyotypes
images of condensed chromosomes
in eukaryotic dna packaging, what are proteins divided into
histones and non-histone chromosomal proteins
what is a chromatin?
dna + protein complex
what is the nucleosome?
the functional unit of dna packaging
contains 8 histones (2x H2A, H2B, H3, H4)
what surrounds core histones?
146 base pairs of dna
how many times does dna wrap around the histone core?
1.65x
what is ‘string of beads’?
complex of histones and dna
what is the function of histone 1?
plays a role in stacking the two nucleosomes to form a chromatosome
explain the steps required in dna packaging
1) start w/ dna
2) dna wraps around histones to form nucleosomes
3) nucleosomes stack to form chromatin
4) chromatin is then further packed by the addition of scaffold proteins
in interphase what are the two types of chromatin?
euchromatin and heterochromatin
describe euchromatin
less condensed
does not strongly stain
major genes involved in transcription
describe heterochromatin
highly condensed
visible by light microscopy in interphase eukaryotes
gene activity suppressed
