Cell Cycle

Question 1

why is cell division required?

Answer 1

replace dead or injured cells and for tissue growth

Question 2

what is the process of apoptosis?

Answer 2

no products released, cell breaks into apoptotic bodies and organelles still functional

Question 3

what is the process of necrosis?

Answer 3

structure of the nucleus changes, cell ruptures and organelles are no longer functional

Question 4

what is cell growth controlled by?

Answer 4

suicide genes

Question 5

what makes up interphase?

Answer 5

G1, S and G2 phase

Question 6

what occurs in G1?

Answer 6

protein synthesis, organelles duplicated, centrosome replication begins

Question 7

how long does G1 last?

Answer 7

8-10 hours

Question 8

what is needed to pass G1?

Answer 8

growth factors

Question 9

what happens in S phase?

Answer 9

DNA replicates, assembly of new chromatin

Question 10

how long does S phase last?

Answer 10

8 hours

Question 11

what happens in G2 phase?

Answer 11

synthesis of enzymes an proteins needed for cell division, centrioles replicated

Question 12

how long does G2 last?

Answer 12

4-6 hours

Question 13

what is karyokinesis?

Answer 13

division of nucleus

Question 14

how long does mitosis last?

Answer 14

an hour or less

Question 15

what is the main features of prophase?

Answer 15

chromatin condenses into chromosomes, nucleoli disappear, microtubules disassemble

Question 16

what happens in metaphase?

Answer 16

chromosomes undergo max coiling, arranged along the equator

Question 17

what happens in anaphase?

Answer 17

kinetochore splits, chromatids are now daughter chromosomes nd move to opposite poles

Question 18

what happens in telophase?

Answer 18

begins after each chromatid splits, chromosomes uncoil and nuclear envelope forms

Question 19

what happens in cytokinesis?

Answer 19

cleavage furrow develops separating the two daughter cells

Question 20

what regulates the initiation of cell growth?

Answer 20

cyclin dependant kinases

Question 21

how are cyclin dependant kinases controlled?

Answer 21

switched on and off by cyclins

Question 22

what are growth signals?

Answer 22

proteins that singal a cell to carry out cell growth

Question 23

where do growth factors come from?

Answer 23

often produced by a neighbouring cell that has just died

Question 24

what do the growth factors do?

Answer 24

binds to a receptor on the cell surface and activates a signalling cascade

Question 25

what is anchorage dependance?

Answer 25

cells can only divide when attached to the ECM

Question 26

what are all three cycle checkpoints?

Answer 26

late G1, end of G2 and the M checkpoint

Question 27

what happens in the G1 checkpoint?

Answer 27

determines conditions are favourable for division and if not they move to G0

Question 28

what happens in the G2 checkpoint?

Answer 28

ensures that all chromosomes have been replicated and the DNA is not damaged

Question 29

what happens in the M checkpoint?

Answer 29

determines if all sister chromatids are attached to the spindle otherwise it does not proceed

Question 30

in what cells is G1 checkpoint important?

Answer 30

cells that continuously divide such as gut epithelial cells an stem cells

Question 31

how are cells able to pass the G1 checkpoint?

Answer 31

by the expression of cyclin D proteins which are induced by growth factors

Question 32

what does cyclin D bind to?

Answer 32

CDK4 to form a CDK4-cyclin D complex

Question 33

what do CDK4-cyclin D complexes do?

Answer 33

phosphorylate the tumour suppressor gene called Rb

Question 34

what does phosphorylated Rb then do?

Answer 34

relieves the inhibition of the transcription factor E2F

Question 35

what does E2F do as a result?

Answer 35

express the proteins needed for cell growth