cell cycle

Question 1

division in specific cells

Answer 1

cells divide at different rates eg embryonic vs adult cells depends for necessity for renewal eg intestinal cells

Question 2

cell division in tumours

Answer 2

apart from mutations in TMS/aneuploidy, solid tumours are aneuploidy (abnormal chromosome number)- contact inhibition of growth (when cells know when to stop growing) not present, of protein levels of cell cycle regulators affected

Question 3

stages of cell cycle

Answer 3

interphase (duplication)- not just DNA, but also organelles and protein synthesis M phase ie mitosis: nuclear and cytoplasmic (cytokinesis) division coordination

Question 4

vulnerable period of cell cycle and why

Answer 4

M phase, as cells more easily killed, and DNA damage can’t be repaired

Question 5

phases of interphase

Answer 5

G0- cell cycle machinery broken down, cell resting G1 (gap)- decision point S- DNA/protein synthesis+ replication of organelles G2 (gap)- is all DNA produced

Question 6

centrosome

Answer 6

double barrel composed of 2 centrioles- forms microtubule organising centre and (polymerisation of them occurs from them) mitotic spindle

Question 7

DIAGRAM what occurs in prophase

Answer 7

chromatin condense- forms two sister chromatids with a centromere in the middle, with kinetochores on each side centrosomes also go on opposite side

Question 8

DIAGRAM spindle formation and interaction

Answer 8

radial microtube arrays (called asters) from AROUND each chromosome, and meet in the middle to form polar microtubles

Question 9

early prometaphase

Answer 9

early- nuclear breaks down, which spindle formation having already occurred: chromosomes attach to spindle microtubules via KINETOCHORES

Question 10

late prometaphase

Answer 10

chromosomes attached to each pole go to middle

Question 11

DIAGRAM anaphase and subphases

Answer 11

sister chromatids separate (COHESIN hold chromatids together) anaphase A- cohesion broken down, microtubules contract and get shorter anaphase B- DAUGHTER CHROMOSOMES pulled to opposite poles AND spindle poles (centrosomes) move outwards

Question 12

telophase

Answer 12

daughter chromosomes arrive at spindle, nuclear envelope forms again, and contractile ring forms (needed for cytokinesis)

Question 13

spindle assembly checkpoint and proteins needed- also where occurs

Answer 13

make sure that chromosomes are aligned at equator, and that chromosomes are attached to microtubules- occurs between prometaphase and metaphase needs BUB kinases and CENP-E

Question 14

DIAGRAM misattachment of microtubules to kinetochores- types and overall

Answer 14

monotelic attachment- only 1 sister chromatid attaches syntelic- both chromatids attach to same tubule= go to same daughter cells/pole merotelic- multiple microtubules attach to same sister chromatid= chr LOSS in cytokinesis leads to aneuploidy amphelic- normal

Question 15

aberrant centrosome/DNA duplication

Answer 15

leads to more than 2 centrosomes= more than 2 daughter cells= aneuploidy

Question 16

how anti-cancer therapy works and examples and their mechanisms

Answer 16

cause GROSS chromosome missegregation, meaning cells is unviable so dies chekpoint kinase (checkpoint in G2) inhibitors taxons and vinca alkaloids change microtubule mechanicsms, unattached kinetochores, and long term mitosis (ie more vulnerable)

Question 17

what happens in sth goes wrong during cell cycle

Answer 17

cell cycle arrest at checkpoints: often temporary OR apoptosis if DNA damage too great/chromosome abnormalities

Question 18

DIAGRAM how tumours affects checkpoint

Answer 18

growth factors affect G1 checkpoint, allowing S phase to occur- tumour affect this tumours also effect G2 checkpoint (for DNA damage) or metaphase checkpoint (for alignment)

Question 19

G0 and how tumours affect it

Answer 19

tumours also prevents exit of cell cycle at G0, so no resting state in this stage, cells are not dividing, but are NOT dormant the exit from G0 back into cell cycle needs growth factors, which activates a signalling cascade

Question 20

DIAGRAM how peptide growth factors work

Answer 20

dimeric ligand binds to a monomeric receptor, forming dimers, as the 2 kinase domains brought together and are phospohrylated receptor protein tyrosine kinase involved, activating the receptor

Question 21

how phosphorylation occurs

Answer 21

negative phosphate from ATP added to hydroxyl group of serine, threonine or tyrosine- causes change in shape- doesn’t just phosphorylate kinase domain, but also other sites too, causing a kinase cascade

Question 22

kinase cascade

Answer 22

kinases are regulated by other kinases- 1 kinase is phosphorylated, and it phosphorylates a second kinase this phosphorylation is reverse by PHOSPHATASES