Lecture 9

Question 1

each lamp brush chromosome consists of two aligned sets of –

Answer 1

paired chromatids

Question 2

arrested at the diplotene stage of meiosis

Answer 2

oocyte

Question 3

genes present in the loops are being

Answer 3

actively expressed

Question 4

the – method of determing the position of loops in interphase chromosomes

Answer 4

chromosome conformation capture (3C)

Question 5

cells treated with formaldehyde –>

Answer 5

covalent DNA-protein and DNA-DNA cross links

Question 6

DNA is then treated with a restriction nuclease that chops the DNA into many pieces, cutting at strictly defined nucleotide sequences and forming sets of –

Answer 6

identical “cohesive hends”

Question 7

cohesive end are made to join through their

Answer 7

complementary base pairing

Question 8

Prior to the ligation step, DNA is diluted so that the fragments that have been kept in – )through cross-linking) are the ones most likely to join

Answer 8

close proximity

Question 9

Reverse cross links (by heat treatment and proteolysis) and the newly ligated fragments of DNA are – and – by PCR

Answer 9

identified and quantified

Question 10

DNA product is only observed by 3C if proteins hold the two DNA sequences –

Answer 10

close together in the cell

Question 11

chromosome is folded into a series of –

Answer 11

looped domains

Question 12

each loop domain contains

Answer 12

50,000 -200,000 nucleotide pairs

Question 13

DNA keep replicating but cell not dividing –>

Answer 13

synthesize large amount of certain proteins

Question 14

about – of the polytene DNA is in 3700 bands

Answer 14

95%

Question 15

about – of the polytene is in 3700 interbands

Answer 15

5%

Question 16

– in polytene chromosome puffs

Answer 16

RNA synthesis

Question 17

chromatin loops – when the genes within them are expressed

Answer 17

decondense

Question 18

each of the 46 human chromosomes tend to occupy – within the nucleus

Answer 18

its own discrete territory

Question 19

nucleolus =

Answer 19

assembly of ribosome subunit and rRNA synthesis

Question 20

heterochromatic regions are often associated with the –

Answer 20

nuclear lamina

Question 21

T/F: the gene-rich regions are largely absent in the DNA near the nuclear envelope

Answer 21

true

Question 22

most regions of our chromosome are folded into a conformation called

Answer 22

fractal globule every 5 megabase

Question 23

fractal globule is a knot-free conformation that permits dense packing yet

Answer 23

retains an ability to easily fold and unfold

Question 24

chromatin can move to specific sites to

Answer 24

alter gene expression

Question 25

T/F: the position of a gene changes when it becomes highly transcribed

Answer 25

true

Question 26

large loop of chromatin – when a gene is on

Answer 26

expands

Question 27

network of – form a set of distinct biochemical environments inside the nucleus

Answer 27

proteins and RNA

Question 28

Each chromosome at metaphase contains

Answer 28

two sister chromatids

Question 29

each chromatid contains – generated by DNA replication

Answer 29

one of two identical sister DNA molecules

Question 30

short region of DNA double helix

Answer 30

2 nm

Question 31

histone core

Answer 31

11 nm

Question 32

zig zag model of chromatin fiber of packed nucleosomes during interphase

Answer 32

30 nm

Question 33

each DNA molecule has been packaged into a mitotic chromosome that is – shorter than its fully extended length

Answer 33

10,000 fold