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
