L2 Mitosis Flashcards Preview

BMS242 Cell & Molecular > L2 Mitosis > Flashcards

Flashcards in L2 Mitosis Deck (50)
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1

How does DNA normally exist in cells

decondensed, spread out

2

What are the two forms of decondensed DNA

heterochromatin and euchromatin

3

What is a chromosome

linear DNA molecule

4

What is the centromere

region where the spindle attaches

5

What are homologous chromosomes

same genes arranged in same order

6

How are homologous chromosomes inherited

one from mother, one from father

7

What are chromatids

newly copied DNA strands joined to each other by a centromere

8

What is pulled apart

chromatids

9

Describe prophase

condensation of sister chromatids

10

Describe metaphase

attachment of mitotic spindle to kinetochore by microtubules

11

Describe anaphase

separation of sister chromatids to opposite poles

12

Describe telophase

nuclear envelope reassembly, start of cytokinesis

13

Why is prophase important

gets chromosomes into the right form for mitosis

14

During what phase can chromosomes get tangled

anaphase

15

What checks chromosome tangling

decatenation check point

16

What can chromosome tangling lead to

aneuploidy and chromosome rearrangements in daughter cells

17

What is a genetic model for the cell cycle

yeast

18

What are the advantages of yeast as a genetic model

rapid division, cell cycle control genes highly conserved, haploid or diploid

19

What is a use of haploid and diploid yeast

diploids are used to maintain lethal mutations - then studied in haploids

20

Why is yeast more flexible than mammalian cells

temperature sensitive mutations - allows growth at permissive temperature

21

What is used as a biochemical model for the cell cycle

xenopus

22

What are the advantages of xenopus as a biochemical model

easy to collect eggs, large size, rapid division, manipulated by injection

23

What complex is degraded quickly part way through M phase

Cyclin B complex

24

What drives the cell through M phase

M-Cdk

25

What must M-Cdk trigger

mitotic spindle assembly, chromosome condensation, breakdown of nuclear envelope

26

What is the effect of the inhibitory phosphate on the M-Cdk complex

keeps the protein complex inactive

27

What removes the inhibitory phosphate from the M-Cdk complex

phosphatase Cdc25

28

What activates phosphatase Cdc25

S-Cdk complexes

29

What is the effect of removing the inhibitory phosphate from M-Cdk complex

activates the M-Cdk

30

What is the effect of an active M-Cdk complex

positive feedback - build up of active M-Cdk complexes

31

What is the effect of active M-Cdk complexes

rapid activation of mitosis

32

What does APC stand for

anaphase promoting complex

33

What is progression through metaphase/anaphase transition driven by

protein destruction

34

What is loss of heterozygosity

cross chromosomal event that results in loss of the entire gene

35

Name the three ways that loss of heterozygosity can be induced

non-disjunction, mitotic recombination, gene conversion

36

Describe non-disjunction

wrong number of chromosomes

37

What can cause non-disjunction

lagging chromosomes

38

When can non-disjunction occur

anaphase

39

What is central to separation of chromosomes

spindle

40

What is the function of kinetochore microtubules

attach to chromosomes at the kinetochore

41

What is the function of astral microtubules

position the spindle

42

How does the cell detect incorrectly lined up kinetochores

low tension

43

True or false - properly lined up kinetochores are unstable

false - stable - therefore higher tension

44

What is the function of separase

destroy bridges between chromatids

45

What is a problem if a cell is hemizygous

if the allele is mutant there is no normal copy of the gene

46

What are the downstream consequences of no normal gene copy

no active proteins are made

47

Describe mitotic recombination

DNA swaps between chromatin arms

48

What can some mitotic recombinations cause

two mutant alleles on one set of chromatids

49

What enzyme causes gene conversion

DNA polymerase

50

Describe gene conversion

DNA polymerase jumps between 2 DNA molecules, replicates another allele