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CMB > Cell Cycle > Flashcards

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
Q

The protein family that are the central components of the cell-cycle control system.

A

Cyclin-dependent kinases (Cdks)

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26
Q

Regulatory proteins that control the cyclical changes in Cdk activity.

A

Cyclins

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27
Q

Classes of Cyclins

A
  1. G1/S-Cyclins
  2. S-Cyclins
  3. M-Cyclins
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28
Q

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.

A

G1/S-Cyclins

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29
Q

Binds to Cdks soon after the Start transition; promote chromosome duplication during S phase.

A

S-Cyclins

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30
Q

These cyclins activate Cdks that drive entry into mitosis at the G2/M transition.

A

M-Cyclins

31
Q

Help govern the activities of the G1/S-Cyclins.

A

G1-Cyclins

32
Q

Two main roles of cyclins:

A
  1. Activate Cdk partner.
  2. Guide the Cdk to specific target proteins.
33
Q

Functional units formed when a cyclin binds to a Cdk.

A

Cyclin-Cdk Complexes

34
Q

Enzymes (kinases) that control progression through the cell cycle by phosphorylating specific proteins.

A

Cyclin-Dependent Kinases (Cdk)

35
Q

Proteins that regulate the cell cycle by activating Cdks.

A

Cyclins

36
Q

Enables full activation of the Cyclin-Cdk Complex

A

Cdk-activating Kinase (CAK)

37
Q

Cyclin binding to the active site of Cdk results in _____ _____ .

A

Partial Activation

38
Q

The primary determinant of Cdk activity during the cell cycle.

A

Cyclin levels

39
Q

Additional mechanisms that help control Cdk activity at specific stages of the cell cycle:

A
  1. Inhibitory Phosphorylation
  2. Cdk Inhibitor Proteins
40
Q

Bind directly to cyclin-Cdk complexes and change their shape, making them inactive.

A

Cdk Inhibitor Proteins (CKIs)

41
Q

Addition of phosphate groups to specific amino acids in the Cdk’s active site hat can turn off Cyclin-Cdk Complexes

A

Inhibitory Phosphorylation

42
Q

Adds phosphate groups inhibiting Cdk activity

A

Wee 1 Kinase

43
Q

Removes phosphate groups, reactivating Cdk activity

A

Cdc25 Phosphatase

44
Q

Used primarily to help govern the G1/S-Cdks and S-Cdks

A

Cdk Inhibitor Proteins (CKIs)

45
Q

Used for the regulation of M-Cdk activity at the onset of mitosis.

A

Inhibitory Phosphorylation

46
Q
  • The key regulator of the metaphase-to-anaphase transition.
  • A member of the ubiquitin ligase family
A

anaphase-promoting complex or cyclosome (APC/C)

47
Q

The progression through the metaphase-to-anaphase transition is triggered by ______ ______ .

A

Protein destruction

48
Q

The APC/C catalyzes the ubiquitylation and destruction of two major types of proteins:

A
  1. securin
  2. S- and M-cyclins
49
Q

A protein that protects the linkages that hold sister-chromatid pair together in early mitosis.

A

Securin

50
Q
  • 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
A

SCF

51
Q

Regulates APC/C activity

A
  1. Cdc20 (mid-mitosis)
  2. Cdh1 (late mitosis thru early G1)
52
Q

Regulates SCF activity

A

F-box Proteins

53
Q

protein complex that plays a crucial role in holding sister chromatids together after DNA replication.

A

Cohesin

54
Q

Unwinds the double helix

A

DNA helicase

55
Q

Chromatids are compacted

A

Chromosomes condensation

56
Q

Two sisters are resolved into distinct, separable units

A

Sister-chromatid resolution

57
Q

consists of a cloud of
pericentriolar matrix that surrounds a pair of
centrioles

A

Centrosome

58
Q

move toward the plus ends; slide the two antiparallel microtubules past each other toward the spindle poles, pushing the poles apart

A

Kinesin-5

59
Q

are minus-end directed motors; cross-link antiparallel interpolar microtubules at the spindle midzone and tend to pull the poles together

A

Kinesin-14

60
Q

Chromokinesins; plus-end directed motors that associate with chromosome arms and push the attached chromosome away from the pole

A

Kinesin-4/10

61
Q

minus-end directed motors; motors pull the spindle poles toward the cell cortex and away from each other

A

Dynein

62
Q

Persists as a tether between the two daughter cells and contains the remains of the central spindle

A

Midbody

63
Q

membranes are created around each nucleus in one round of coordinated cytokinesis

A

Cellularization

64
Q

segregate the homologs; duplicated paternal and maternal homologs pair up alongside each other

A

Meiosis I

65
Q

No further DNA replication; the sister chromatids pulled apart and segregated; produces four haploid daughter cell

A

Meiosis II

66
Q

homologs condense and pair and genetic recombination begins

A

Leptotene

67
Q

synaptonemal complex begins to assemble at sites where the homologs are closely associated and recombination events are occurring

A

Zygotene

68
Q

assembly process is complete, and the homologs are synapsed along their entire lengths

A

Pachytene

69
Q

disassembly of the synaptonemal complexes and the concomitant condensation and shortening of the chromosomes

A

Diplotene

70
Q

segregation of homologs

A

Diakinesis

71
Q

the individual crossover events between non-sister chromatids can be seen as inter-homolog connections

A

Chiasmata

72
Q

cohesins near the centromeres are protected from separase in meiosis I by a kinetochore-associated protein called

A

Shugoshin

73
Q

Functions of crossing-over

A
  1. Hold homologs together
  2. Genetic diversification
74
Q

When homologs fail to separate; some of the resulting haploid gametes lack a particular chromosome, while others have more than one copy of it

A

Nondisjunction

CMB (5 decks)

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