Alberts, Ch 17 - Cell Cycle Flashcards

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1
Q

Anaphase A

A

Stage of mitosis, initial poleward movement of the chromosomes during which kinetocore microtubules shorten

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2
Q

Anaphase B

A

Stage of mitosis when spindle poles separate and daughter chromosomes move toward opposite poles

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3
Q

Anaphase-promoting complex (APC/C)

A

Ubiquitin ligase that catalyzes ubiquitylation and destruction of securin and M- and S-cyclins initiating separation of sister chromatids in metaphase-to-anaphase transition during mitosis, also known as cyclosome

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4
Q

Astral microtubule

A

In the mitotic spindle any of the microtubules radiating from the aster which are not attached to kinetochore of a chromosome

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5
Q

ATM

A

Ataxia telangiectasia mutated protein, protein kinase activated by double-strand DNA breaks, if breaks not repaired ATM initiates signal cascade that culminates in cell cycle arrest

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6
Q

ATR

A

Ataxia telangiectasia and Rad3 related protein, protein kinase activated by DNA damage, if damage remains unrepaired helps initiate signal cascade that culminates in cell cycle arrest

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7
Q

Bi-orientation

A

Attachment of sister chromatids to opposite poles of mitotic spindle so that they move to opposite ends of the cell when they separate in anaphase

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8
Q

Bivalent

A

Four-chromatin structure formed during meiosis consisting of a duplicated chromosome tightly paired with its homologous duplicated chromosome

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9
Q

Cdc20

A

Activating subunit of anaphase-promoting complex

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10
Q

Cdc25

A

Protein phosphatase that dephosphorylates Cdks and increases their activity

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11
Q

Cdc6

A

Protein essential in preparation of DNA for replication, with Cdt1 binds to origin recognition complex on chromosomal DNA and helps load the Mcm proteins onto the complex to form prereplicative complex

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12
Q

Cdh1

A

Activating subunit of anaphase-promoting complex

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13
Q

Cdk inhibitor protein (CKI)

A

Protein that binds to and inhibits cyclin-Cdk complexes, involved in control of G1 and S phases

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14
Q

Cdk-activating kinase (CAK)

A

Protein kinase that phosphorylates Cdks in cyclin-Cdk complexes activating Cdk

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15
Q

Cdt1

A

Protein essential in preparation of DNA for replication, with Cdc6 binds to origin recognition complexes on chromosomes and helps load the Mcm proteins on to the complex forming prereplicative complex

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16
Q

Cell cycle

A

Reproductive cycle of a cell, orderly sequence of events by which cell duplicates its chromosomes and other cell contents and divides into two

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17
Q

Cell-cycle control system

A

Network of regulatory proteins that governs progression of eukaryotic cell through cell cycle

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18
Q

Centrosome

A

Centrally located organelle of animal cells that is primary microtubule-organizing center (MTOC) and acts as the spindle pole during mitosis, contains a pair of centrioles

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19
Q

Chiasma (plu. Chiasmata)

A

X-shaped connection visible between paired homologous chromosomes during meiosis, represents a site of chromosomal crossing-over, form of genetic recombination

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20
Q

Condensin

A

Complex of proteins involved in chromosome condensation prior to mitosis, target for M-Cdk

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21
Q

Contractile ring

A

Ring containing actin and myosin that forms under the surface of animal cells undergoing cell division, contracts to pinch the two daughter cells apart

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22
Q

Cyclin

A

Protein that periodically rises and falls in concentration in step with eukarotic cell cycle, activates protein kinases (Cdks) and helps control progression from one stage of cell cycle to the next

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23
Q

Cyclin-dependent kinase (Cdk)

A

Protein kinase that has to be complexed with cyclin protein in order to act, different cyclin-Cdk complexes trigger different steps in cell-division cycle by phosphorylating specific target proteins

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24
Q

Cyclin-Cdk complex

A

Protein complex formed periodically during eukaryotic cell cycle as level of particular cyclin increases, Cdk then becomes partially activated

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25
Q

Cytokinesis

A

Division of cytoplasm of cell into two, distinct from associated division of its nucleus, part of M phase

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26
Q

E2F protein

A

Transcription regulatory protein that switches on many genes that encode proteins required for entry into S phase

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27
Q

G0

A

State of withdrawal from eukaryotic cell-division cycle by entry into quiescent digression from G1 phase, common, sometimes permanent state for differentiated cells

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28
Q

G1 phase

A

Gap 1 phase of eukaryotic cell cycle, between end of mitosis and start of DNA synthesis

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29
Q

G1-Cdk

A

Cyclin-Cdk complex formed in vertebrate cell by G1-cyclin and corresponding Cdk

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30
Q

G1-cyclin

A

Cyclin present in G1 phase, forms complexes with Cdks that help govern activity of G1/S-cyclins

31
Q

G1/S-Cdk

A

Cyclin-Cdk complex formedby G1/S-cyclin and corresponding Cdk

32
Q

G1/S-cyclin

A

Cyclin that activates Cdks in late G1 and helps trigger progression through Start resulting in commitment to cell-cycle entry, levels fall at start of S phase

33
Q

G2 phase

A

Gap 2 phase, between end of DNA synthesis and beginning of mitosis

34
Q

G2/M transition

A

Point in eukaryotic cell cycle at which cell checks for completion of DNA replication before triggering early mitotic events that lead to chromosome alignment on the spindle

35
Q

Geminin

A

Protein that prevents formation of new prereplicative complexes during S phase and mitosis ensuring that chromosomes are replicated only once in each cell cycle

36
Q

Growth factor

A

Extracellular signal protein that can stimulate a cell to grow, often have other functions as well such as stimulating cell to survive or proliferate, examples epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)

37
Q

Interphase

A

Long period of cell cycle between one mitosis and the next, includes G1, S and G2 phases

38
Q

Interpolar microtubule

A

In mitotic or meiotic spindle, microtubule interdigitating at the equator with microtubules emanating from the other pole

39
Q

Kinetochore

A

Large protein complex that connects the centromere to microtubules of mitotic spindle

40
Q

Kinetochore microtubule

A

In mitotic or meiotic spindle, a microtubule that connects the spindle pole to kinetochore of chromosome

41
Q

M-Cdk

A

Cyclin-Cdk complex formed by M-cyclin and corresponding Cdk

42
Q

M-cyclin

A

Cyclin found in all eukaryotic cells that promotes events of mitosis

43
Q

Meiosis I

A

First chromosome segregation following meiotic chromosome duplication, segregates homologs

44
Q

Meiosis II

A

Second chromosome segregation following meiotic chromosome duplication, segregates sister chromatids of each homolog

45
Q

Metaphase-to-anaphase transition

A

Transition preceding sister chromatid seperation at anaphase, if cell not ready to proceed to anaphase cell cycle halted here

46
Q

Mitogen

A

Extracellular signal molecule that stimulates cells to proliferate

47
Q

Mitotic spindle

A

Bipolar array of microtubules and associated molecules that forms during mitosis and serves to move duplicated chromosomes apart

48
Q

Microtubule flux

A

Movement of individual tubulin molecules in the microtubules of the spindle toward the poles by loss of tubulin at their minus ends, helps generate poleward movement of sister chromatids after they separate in anaphase

49
Q

Myc

A

Transcription regulatory protein that is activated when a cell is stimulated to grow and divide by extracellular signals, activated transcription of many genes, including those that stimulate cell growth

50
Q

Nondisjunction

A

Event occuring occasionally during meiosis in which a pair of homologous chromosomes fails to separate so that resulting germ cell has either too many or too few chromosomes

51
Q

Origin recognition complex (ORC)

A

Large protein complex that is bound to DNA at origins of replication in eukaryotic chromosomes throughout the cell cycle

52
Q

p53

A

Transcription regulatory protein that is activated by damage to DNA and is involved in blocking further progression through cell cycle, also a tumor suppressor gene that is mutated in about half of human cancers (the gene encoding the protein)

53
Q

Pairing

A

In meiosis lining up of the two homologous chromosomes along their length

54
Q

Prereplicative complex (preRC)

A

Multiprotein complex that is assembled at origins of replication during late mitosis and early G1 phases, prerequisite to license assembly ofpreinitiation complex and subsequent initiation of DNA replication

55
Q

Ras

A

Monomeric GTPase of Ras superfamily that helps to relay signals from cell-surface receptor tyrosine kinase receptors to nucleus in response to signals that stimulate cell division, also family of proto-oncogenes that frequently mutate in cancer (code for the protein)

56
Q

Replicative cell senscence

A

Phenomenon observed in primary cell cultures in which cell proliferation slows down and finally irreversibly halts

57
Q

Restriction point

A

Important transition at end of G1, commits cell to enter S phase

58
Q

Retinoblastoma (Rb) protein

A

Tumor suppressor protein involved in regulation of cell division, mutated in cancer retinoblastoma and other tumors, normal activity is to regulates cell cycle by binding to and inhibiting E2F proteins blocking progression to DNA replication and cell division

59
Q

S-Cdk

A

Cyclin-Cdk complex formed by S-cyclin and corresponding Cdk

60
Q

SCF

A

Family of ubiquitin ligases formed as complex of several different proteins, one involved in regulating cell cycle, directing destruction of inhibitors of S-Cdks in late G1 and promoting activation of S-Cdks and DNA replication

61
Q

S-cyclin

A

Member of class of cyclins that accumulate during late G1 and bind Cdks soon after progression through Start, help stimulate DNA replication and chromosome duplication, levels remain high until late mitosis after which destroyed

62
Q

Separase

A

Protease that cleaves cohesin protein linkages that hold sister chromatids together, acts at anaphase enabling chromatid separation and segregation

63
Q

Sister chromatids

A

Tightly linked pair of chromosomes that arise from chromosome duplication during S phase, they separate during M phase and segregateinto different daughter cells

64
Q

Spindle assembly checkpoint

A

Regulatory system that operates during mitosis to ensure that all chromosomes are properly attached to the spindle before sister chromatid separation starts

65
Q

Start

A

Important transition at end of G1 in eukaryotic cell cycle, passage through commits cell to enter S phase

66
Q

Synaptonemal complex

A

Structure that holds paired homologous chromosomes tightly together in pachytene of prophase I in meiosis and promotes final steps of crossing over

67
Q

Syncytium

A

Mass of cytoplasm containing many nuclei enclosed by single plasma membrane, typically result of cell fusion or series of incomplete division cycles in which nuclei divide but cell does not

68
Q

Telomerase

A

Enzyme that elongates telomere sequences in DNA

69
Q

Telophase

A

Final stage of mitosis in which two sets of separated chromosomes decondense and become enclsoed by nuclear envelope

70
Q

Wee1

A

Protein kinase that inhibits Cdk activity by phosphorylating amino acids in Cdk active site, important in regulating entry into M phase

71
Q

Prophase

A

First stage of mitosis during which replicated chromosomes condense, mitotic spindle assembles

72
Q

Prometaphase

A

Second stage of mitosis, nuclear envelope breaks down, enables spindle attachment to chromosomes

73
Q

Metaphase

A

Third stage of mitosis, chromosomes aligned at equator of spindle, kinetochore microtubules attach sister chromatids to opposite poles of spindle

74
Q

Anaphase

A

Stage of mitosis during which sister chromatids separate and move away from each other, in meiosis chromosome homolog pairs separate (I) and sister chromatids separate (II)