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Cell Cycle Flashcards

1
Q

When a cell reproduces by performing an orderly sequence of events in which it duplicates its contents and then divides in two.

A

Cell Cycle

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2
Q

Chromosome duplication occurs during _____

A

S phase (S for DNA synthesis)

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3
Q

Requires 10–12 hours and occupies about half of the cell-cycle time in a typical mammalian cell.

A

S Phase

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4
Q

Chromosome segregation and cell division occur in _____

A

M Phase

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5
Q

M phase comprises two major events:

A

Mitosis (nuclear division) & Cytokinesis (cytoplasmic division)

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6
Q

Rigid, compact rods formed from duplicated DNA molecules during prophase; these remain linked by sister-chromatid cohesion.

A

Sister chromatids

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7
Q

Specialized protein linkages that tightly hold sister chromatids together.

A

Sister-chromatid Cohesion

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8
Q

An early stage of mitosis where DNA molecules are disentangled and condensed into sister chromatids.

A

Prophase

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9
Q

A giant bipolar array of microtubules that attaches to sister chromatids and facilitates their movement during mitosis.

A

Mitotic Spindle

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10
Q

A stage in mitosis where sister chromatids align at the spindle equator, attached to opposite poles of the mitotic spindle.

A

Metaphase

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11
Q

A stage of mitosis where the destruction of sister-chromatid cohesion separates the sister chromatids, which are pulled to opposite spindle poles.

A

Anaphase

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12
Q

A stage of mitosis where segregated chromosomes are packaged into separate nuclei.

A

Telophase

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13
Q

The process of cell division that cleaves the cell into two, with each daughter cell inheriting one of the two nuclei.

A

Cytokinesis

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14
Q

The Eukaryptic Cell Cycle is divided into __ , __ , __ , and __ phases.

A

G1, S, G2, and M

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15
Q

The combination of G1, S, and G2 phases; a period of growth and preparation for mitosis, excluding M phase.

A

Interphase

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16
Q

A specialized resting state that cells can enter from G1 if extracellular conditions are unfavorable; cells can remain in this state for varying lengths of time or permanently.

A

G0 Phase

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17
Q

The gap phase between M phase and S phase, where the cell grows and monitors conditions to determine if it can proceed to DNA replication.

A

G1 Phase

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18
Q

The gap phase between S phase and mitosis, where the cell continues to grow and prepares for mitosis.

A

G2 Phase

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19
Q

If extracellular conditions are favorable and signals to grow and divide are present, cells in early G1 or G0 progress through a commitment point near the end of G1 known as

A

Start (yeasts) or Restriction Point (mammalian cells)

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20
Q

An artificial thymidine analog incorporated into newly synthesized DNA during S phase, allowing S-phase cells to be identified using anti-BrdU antibodies.

A

Bromodeoxyuridine (BrdU)

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21
Q

A device used for rapid and automatic analysis of large numbers of cells, often to measure DNA content for determining cell-cycle stages.

A

Flow Cytometer

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22
Q
  • operates like a timer that triggers the events of the cell cycle in a set sequence.
  • based on a connected series of biochemical switches which initiates a specific cell cycle event.
A

Cell-Cycle Control System

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23
Q

Characteristics of the Cell-Cycle Control System

A
  1. Binary (on/off)
  2. Remarkably robust and reliable
  3. Highly adaptable
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24
Q

The Cell-Cycle Control System governs the cell-cycle progression at three major regulatory transitions:

A
  1. Start (restriction point)
  2. G2/M transition
  3. Metaphase-to-Anaphase Transition
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25
The protein family that are the central components of the cell-cycle control system.
Cyclin-dependent kinases (Cdks)
26
Regulatory proteins that control the cyclical changes in Cdk activity.
Cyclins
27
Classes of Cyclins
1. G1/S-Cyclins 2. S-Cyclins 3. M-Cyclins
28
These cyclins activate Cdks in late G1, facilitating the cell's commitment to enter the cell cycle and begin DNA replication. Their levels decline in S phase.
G1/S-Cyclins
29
Binds to Cdks soon after the Start transition; promote chromosome duplication during S phase.
S-Cyclins
30
These cyclins activate Cdks that drive entry into mitosis at the G2/M transition.
M-Cyclins
31
Help govern the activities of the G1/S-Cyclins.
G1-Cyclins
32
Two main roles of cyclins:
1. Activate Cdk partner. 2. Guide the Cdk to specific target proteins.
33
Functional units formed when a cyclin binds to a Cdk.
Cyclin-Cdk Complexes
34
Enzymes (kinases) that control progression through the cell cycle by phosphorylating specific proteins.
Cyclin-Dependent Kinases (Cdk)
35
Proteins that regulate the cell cycle by activating Cdks.
Cyclins
36
Enables full activation of the Cyclin-Cdk Complex
Cdk-activating Kinase (CAK)
37
Cyclin binding to the active site of Cdk results in _____ _____ .
Partial Activation
38
The primary determinant of Cdk activity during the cell cycle.
Cyclin levels
39
Additional mechanisms that help control Cdk activity at specific stages of the cell cycle:
1. Inhibitory Phosphorylation 2. Cdk Inhibitor Proteins
40
Bind directly to cyclin-Cdk complexes and change their shape, making them inactive.
Cdk Inhibitor Proteins (CKIs)
41
Addition of phosphate groups to specific amino acids in the Cdk’s active site hat can turn off Cyclin-Cdk Complexes
Inhibitory Phosphorylation
42
Adds phosphate groups inhibiting Cdk activity
Wee 1 Kinase
43
Removes phosphate groups, reactivating Cdk activity
Cdc25 Phosphatase
44
Used primarily to help govern the G1/S-Cdks and S-Cdks
Cdk Inhibitor Proteins (CKIs)
45
Used for the regulation of M-Cdk activity at the onset of mitosis.
Inhibitory Phosphorylation
46
- The key regulator of the metaphase-to-anaphase transition. - A member of the ubiquitin ligase family
anaphase-promoting complex or cyclosome (APC/C)
47
The progression through the metaphase-to-anaphase transition is triggered by ______ ______ .
Protein destruction
48
The APC/C catalyzes the ubiquitylation and destruction of two major types of proteins:
1. securin 2. S- and M-cyclins
49
A protein that protects the linkages that hold sister-chromatid pair together in early mitosis.
Securin
50
- Ubiquitylates certain CKI proteins in late G1, helping to control the activation of S-Cdks and DNA replication. - Also destructs G1/S-cyclis in early S-phase
SCF
51
Regulates APC/C activity
1. Cdc20 (mid-mitosis) 2. Cdh1 (late mitosis thru early G1)
52
Regulates SCF activity
F-box Proteins
53
protein complex that plays a crucial role in holding sister chromatids together after DNA replication.
Cohesin
54
Unwinds the double helix
DNA helicase
55
Chromatids are compacted
Chromosomes condensation
56
Two sisters are resolved into distinct, separable units
Sister-chromatid resolution
57
consists of a cloud of pericentriolar matrix that surrounds a pair of centrioles
Centrosome
58
move toward the plus ends; slide the two antiparallel microtubules past each other toward the spindle poles, pushing the poles apart
Kinesin-5
59
are minus-end directed motors; cross-link antiparallel interpolar microtubules at the spindle midzone and tend to pull the poles together
Kinesin-14
60
Chromokinesins; plus-end directed motors that associate with chromosome arms and push the attached chromosome away from the pole
Kinesin-4/10
61
minus-end directed motors; motors pull the spindle poles toward the cell cortex and away from each other
Dynein
62
Persists as a tether between the two daughter cells and contains the remains of the central spindle
Midbody
63
membranes are created around each nucleus in one round of coordinated cytokinesis
Cellularization
64
segregate the homologs; duplicated paternal and maternal homologs pair up alongside each other
Meiosis I
65
No further DNA replication; the sister chromatids pulled apart and segregated; produces four haploid daughter cell
Meiosis II
66
homologs condense and pair and genetic recombination begins
Leptotene
67
synaptonemal complex begins to assemble at sites where the homologs are closely associated and recombination events are occurring
Zygotene
68
assembly process is complete, and the homologs are synapsed along their entire lengths
Pachytene
69
disassembly of the synaptonemal complexes and the concomitant condensation and shortening of the chromosomes
Diplotene
70
segregation of homologs
Diakinesis
71
the individual crossover events between non-sister chromatids can be seen as inter-homolog connections
Chiasmata
72
cohesins near the centromeres are protected from separase in meiosis I by a kinetochore-associated protein called
Shugoshin
73
Functions of crossing-over
1. Hold homologs together 2. Genetic diversification
74
When homologs fail to separate; some of the resulting haploid gametes lack a particular chromosome, while others have more than one copy of it
Nondisjunction

CMB (5 decks)

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