bio 130 lec 5 onwards

Question 1

Repeated Sequences

Answer 1

50%
mobile genetic elements:
LINE
SINE
retrotransposons
dna only transposons

simple repeats
segment duplication

Question 2

unique seueqnces

Answer 2

50%
Protein encoding genome (exons)
Introns
non repetitive DNA that is neither introns nor exons

Question 3

packaging dna, prokaryotes vs eukaryotes

Answer 3

prokaryotes: DNA condensed 1000 fold and complexed with proteins to form nucleoid
eukaryotes: requires chromosome solution

Question 4

The chromosome solution

Answer 4

packaging DNA while keeping accessible for central dogma (dynamic)
process:
23 chromosomes (22 autosome, 1 pair heterosoe XY male)
beads on a string chromatin
Chromatin fiber of packed nucleosome (30nm fiber)
chromatin fiber folded into loops
DNA double helix

Question 5

Histones

Answer 5

Histones are small proteins (rch in lysine & arginine)

Positive charge nutralises negative charge of DNA

Four core histone proteins H2A with H2B
H3 with H4

Histones pair up in octomer core (as dimers)

N-terminal tail (histone tails) sticks out of each protein → can be modified covelently (reversible)

H1 Histone acts like paper clip for nucleosome ( changes direction of linker DNA, helps supercoiling)

Question 6

Interphase
30 nm fibre (cohesins and sequence specific clamp proteins)

Mitosis:
condensins

Answer 6

cohesins draw strands of loops together and sequence specific clamp protein help form chromatin loops

condensins replace cohesins to form double loops

Question 7

Degree of condensation - the spectrum

Answer 7

check goodnotes heterochromatin vs euchromatin

Question 8

interphase chromosomes

Answer 8

chromosomes occupy discrete areas
chromosome cannot directly be seen during interphaser

Question 9

nucleolus

Answer 9

transcription factory where rRna is transcribed

Question 10

haploid genome
vs
diploid genome number of base pairs

Answer 10

3 mil, 6 mil