Chromosomes Flashcards
(29 cards)
autosomes:
22 pairs of normal chromosomes
features: mitochondrial DNA
- high copy number
- from mum
- 13 genes, 22 tRNA
- high mutation rate
endosymbiont theory:
- precursor to eukaryotic cells
- host cell engulf prokaryote which becomes mitochondria
- another photosynthetic= chloroplast
how many bases make up kilobase
1 000 bases
how many make up megabase?
1 000 000 bases
how many bases in human genome:
3000 Mb
chromosome: definition
DNA and proteins
chromatid:
2 sister chromatids join to form chromosome
centromere:
where two chromatids join
how many chromosomes in humans:
23 pairs of chromosomes
features: ploidy
humans have 2n chromosomes (diploid)
- n= haploid
- 3n= triploid
- polyploid more than 2 sets of chromosomes
chromosome structure:
- short (p) and long (q) arm due to uneven centromere
- TP53 gene 17p 13.1
karyotype:
number and appearance of chromosomes of eukaryotic cell
chromatin:
makes up chromosomes: DNA and proteins
euchromatin:
loosely packaged chromatin, actively expressed genes
heterochromatin:
unexpressed (inhibited or silenced) genes
how are they found: euchromatin and heterochromatin
- they could be condensed into heterochromatin and vice versa
- condensed genes are less likely expressed
how is DNA packaged: histones
eukaryotes:
- DNA is wound around histone proteins
- DNA + histones = nucleosome
- 2x of 4 histone proteins = histone core
what are the histone proteins:
H2A
H2B
H3
H4
nucleosome consists of:
- octamer of protein
- 146 bp of DNA
thickness of condensed chromatin fibre:
30 nm thick
chromosome architecture: flow
DNA double helix - (beads on a string) nucleosome - 30 nm fibre - 1 loop - 1 rosette (6 loops) 300 nm fibre - 1 coil (30 rosettes) chromatid 700 nm (10 coils each)
list 4 chromosome mutations:
deletion
duplication
inversion
translocation
deletion:
removes a chromosomal segment
