cell cycle lecture 1

Question 1

cell replication occur via elaborate series of events - stages

Answer 1

S and M

Question 2

stage S of cell replication

Answer 2

DNA synthesis - replication

Question 3

stage M

Answer 3

divide and distribute into 2 daughter cells

Question 4

difference between Xenopus and Drosophilia embryo

Answer 4

Drosphoilis embryo does not have cytokinesis so membrane does not separate nuclei

Question 5

chromatin - contain

Answer 5

complex of histones, non-histone proteins and nuclear DNA

Question 6

chromatin function

Answer 6

DNA compaction and involved in regulation of DNA activities

Question 7

nucleosome contain

Answer 7

DNA and protein (4 histones)

Question 8

nucleosome

Answer 8

basic structural units of chromatin

Question 9

histone contain

Answer 9

tails - no specific structure

has 2 functional domain

Question 10

2 functional domains in histones

Answer 10

amino-terminal

histone fold

Question 11

histone folds

Answer 11

interacting with each other to form dimers

has a hand-shake like interaction

Question 12

histone octamer

Answer 12

formed from dimers H3-H4 and H2A-H2B - 2 copies of each

Question 13

linker histones function

Answer 13

bind to DNA and nucleosome core

changes path of DNA that exits nucleosome

Question 14

DNA exiting nucleosome

Answer 14

affects linker DNA accessibility

organisation of higher order chromatin fibre and chromatin compaction

Question 15

30nm fibre

Answer 15

found in in vitro but not in in vivo

interphase nucleus

Question 16

11nm fibre

Answer 16

beads on a string

unpacked/decondensed

Question 17

unknown form of 30nm fibre

Answer 17

zig-zag model

determined by x-ray crystallography

Question 18

non-histone protein function

Answer 18

binds to areas of chromatin

play regulatory role

Question 19

non-histone protein structural function

Answer 19

50% protein mass of nuclei

Question 20

higher order organisation of chromatin

Answer 20

chromatin arranged in loops and from higher loops

Question 21

protein used in the higher order organised chromatin

Answer 21

CTCF and Cohesin

Question 22

CTCF

Answer 22

protein that binds to DNA

Question 23

Cohesin

Answer 23

4 proteins that circles the DNA keeps loop strands

regulate size of loop

Question 24

TADs

Answer 24

topologically associating domain

groups of loops

Question 25

compartments

Answer 25

grouped TADS | can be transcriptionally active or inactive

Question 26

compartments belong to

Answer 26

individual chromosomal territories - occupied by single chromosomes decondensed after mitosis

Question 27

staining individual chromosomes

Answer 27

using fluorescent staining | multi-colour FISH

Question 28

visualising chromosomes shown

Answer 28

occupied certain areas of nucleus during interphase | not random

Question 29

placement of chromosome territories

Answer 29

some towards periphery - nuclear membrane and other towards centre of nucleus

Question 30

patterns of chromosome arrangement

Answer 30

specific to both cell and tissue type

Question 31

structure of mitotic chromosomes during mitosis

Answer 31

differs from organisation of interphase chromosome

Question 32

structure of mitotic chromosomes during metaphase

Answer 32

individual chromatid containing 1DNA molecule | joined by centromere

Question 33

region where DNA ends

Answer 33

telomeres

Question 34

organisation of folding of DNA

Answer 34

``` DNA sequence - 2nm beads of string - 11nm chromatin fibre - 30nm folded into loops - 700nm entire mitotic chromosome - 1400nm ```

Question 35

condensin

Answer 35

multiprotein complex

Question 36

condensin function

Answer 36

compresses fibres

Question 37

condensing list using condensin complex

Answer 37

linear fibres linear looping axial compression lateral compression

Question 38

formation of chromatin looping in mitotic chromosomes

Answer 38

randomly formed

Question 39

looping structure

Answer 39

scaffolding through the centre of chromatid

Question 40

loops in interphase and mitosis

Answer 40

loops have different formations in interphase

Question 41

cohesin

Answer 41

organises interphase genome

Question 42

codensin

Answer 42

organises genomes during mitosis

Question 43

G1 phase

Answer 43

cell cycle gap phase between M and S phase

Question 44

G2

Answer 44

cell cycle gap phase between S to M phase

Question 45

interphase

Answer 45

period between end of M phase and beginning of the next

Question 46

mitosis

Answer 46

nuclear division in early M phase - duplicated chromosomes are segregated by mitotic spindle and package into nuclei

Question 47

cytokinesis

Answer 47

cell division | in late M phase - duplicated nuclei cytoplasmic components are distributed into daughter cells

Question 48

M phase

Answer 48

duplicate chromosomes segregated and packages into daughter nuclei and distributed into daughter cells

Question 49

S phase

Answer 49

DNA replication and chromosomes duplication occurs