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Module 1 CB > Cell Division and Death II > Flashcards

Cell Division and Death II Flashcards

1
Q

name the 2 phases of the cell cycle

A
  • Interphase
    • Gap1 (G1)
    • DNA Synthesis (S)
    • Gap2 (G2)
  • Mitosis (M)
    • Karyokinesis
      • Division of nucleus
    • Cytokinesis
      • Division of cell cytoplasm
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2
Q

describe the centromere

A
  • Centromere
    • Constricted region that holds sister chromatids together
    • Centric HC
    • Persists throughout interphase
    • Site of kinetochore formation
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3
Q

describe the kinteochore

A
  • Large protein complex (>80 proteins)
  • Forms near the centromere
  • Attach chromosome to mitotic spindle
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4
Q

describe the centrosome

A
  • Microtuble organizing center (MTOC)
    • Contains a pair of centrioles
      • Position of centrioles determines location of mitotic spindle poles
    • Numerous gamma-tubulin rings
      • Nucleating sites for growth of microtubules
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5
Q

describe the mitotic spindle

A
  • Mitotic spindle microtubules will attach to each kinteochore as chromosomes are moved apart later
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6
Q

describe interphase

A
  • S phase
    • replication of DNA
    • replication of centrosome
  • G2 to M transition
    • centrosomes separate
    • move to opposite poles
    • orientation determines the cell’s plane of division
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7
Q

describe prophase

A
  • Beginning of mitosis
  • Condensation of replicated chromosomes
  • chromatids connected at centromere
  • Kinetochores form near centromeres
  • Mitotic spindle assembly
  • Nucleolus disassembles
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8
Q

describe prometaphase

A
  • breakdown of NE
    • dissolution of nuclear lamins
  • Spindle microtubules bind to kinetochores
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9
Q

describe metaphase

A
  • chromosomes align at the equatorial, metaphase plate
    • Kinteochore microtubules
      • Attach sister chromatids to opposite poles
    • Motor proteins
      • Move chromatids into position
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10
Q

describe anaphase

A
  • Anaphase promoting complex (APC)
  • Sister chromatids separate
    • Each pulled to opposite spindle poles
      • motor proteins dyneins
    • Anaphase A
      • Kinetochore microtubules get shorter
    • Anaphase B
      • Overlap microtubules lengthen
      • Spindle poles move apart
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11
Q

describe telophase

A
  • Sister chromatids arrive at opposite poles and decondense
  • Nuclear envelope reassembly
    • Completion of nuclear divions (karyokinesis)
  • Assembly of the contractile ring
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12
Q

describe cytokinesis

A
  • Division of cytoplasm
    • cleavage furrow
    • separation due to the contractile ring
      • actin
      • Myosin II
    • Creation of 2 daughter cells
      • Genetically identical
      • Diploid (2n)
  • Completion of cell cycle
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13
Q

name the cyclin and Cdks at each phase of the cell cycle

A
  • G1
    • Cyclin D, Cdk4/6
    • Retinoblastoma protein (Rb)
    • p53
  • S
    • Cyclins E & A
    • Cdk2
  • G2
    • Cyclin A, Cdk1
  • M
    • Cyclin B, Cdk1
    • APC
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14
Q

describe retinoblastoma protein (Rb) and when it is active/inactive

A
  • Tumor suppressor gene
  • Stable G1
    • Resting cells
    • Rb active
      • Hypophosphorylated Rb binds gene regulatory protein E2F
      • Inhibitor of cell cycle progression
      • Tumor suppressor
  • G1 to S progression
    • Cycling cells
    • Rb inactive
      • ​Hyperphosphorylated Rb due to increased Cyclin D/cdk4/6 activity
      • Dissociates from E2F
      • E2F free to activate gene expression
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15
Q

describe regulation between G2 to M

A
  • Cdc25 phosphatase (takes off phosphate)
    • Removes inhibitory phosphorylation of CDK1
    • Proto-oncogene
  • CDK1 can then bind cyclin B
  • Cyclin B - CDK1 complex activates mitosis
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16
Q

describe p53

A
  • Tumor suppressor gene
  • Mutations in TP53 found in at least 50% of human cancers
  • p53 protein
    • transcription factor, regulates >100 genes
  • Dual role
    • Regulating cell cycle
      • Stimulates transcription of Cdk inhibitory proteins (CDKIs)
    • Initiation of apoptosis
17
Q

describe APC

A
  • Anaphase promoting complex activation
    • makes sure separation of sister chromatids
      • degradation of securin
      • activation of separase
      • cleavage of cohesin complexes
      • pulls sister chromatids apart
    • Degradation of M-phase cyclin B
18
Q

define proto-oncogenes and oncogenes

A
  • Proto-oncogenes
    • Genes whose protein products control cell growth, proliferation and differentiation
    • Normal regulatory molecules
  • Oncogenes
    • Mutated proto-oncogenes
19
Q

describe the funciton of telomerase

A
  • An enzyme complex that elongatest telomere sequences in chromosomal DNA
  • Most somatic cells lack telomerase
    • As a result, when cells divide, telomeres shrink
    • After many division, telomeres cease to function
    • p53 activated and cell cycle arrest; cell senescence
  • Some cancer cells are able to reactivate telomerase
20
Q

describe meiosis I

A
  • separation of homologous chromosomes
  • reduction division
  • chromosome number reduced from 2n to 1n
  • DNA content reduced from 4d to 2d
21
Q

describe meiosis II

A
  • Separation of sister chromatids
  • Equatorial division
  • DNA content reduced from 2d to 1d
22
Q

list and the 5 phases of prophase 1

A
  1. liptotene
  2. zygotene
  3. pachytene
  4. diplotene
  5. diakinesis
23
Q

describe liptotene

A
  • Leptotene
    • Characterized by chromatin condensation
    • Sister chromatids condense & connect to each other
    • Pairing of homologous maternal/paternal chromosomes begins
24
Q

describe zygotene

A
  • Zygotene
    • Synapsis
      • Close association of homologous chromosomes
      • Involves formation of a Syanptonemal Complex
        • Binds chromosomes together
25
Q

describe pachytene

A
  • Pachytene
    • Synaptonemal complex complete
    • Crossing over
      • Transposition of DNA strands between 2 different chromosomes
26
Q

describe diplotene

A
  • The synaptonemal complex begins to break down
  • Homologous chromosomes begin to separate
  • Newly formed junctions between chromosomes (chiasmata) may be apparent
    • Chiasmata indicate crossover may have occurred
  • Sister chromatids remain closely associated
27
Q

describe diakinesis

A
  • Homologous chromosomes condense
  • Nucleolus disappears
  • Nuclear envelope disintegrates
28
Q

describe metaphase I

A
  • Homologous chromosomes randomly align at the equatorial plane
    • Still connected via chiasmata
  • Spindle microtubules attach to kintechores of the sister chromatids
29
Q

describe anaphase I

A
  • Sister chromatids held together at centromere
  • Homologous maternal/paternal chromosomes pulled to opposite poles
    • Random assortment
    • Increases genetic diversity
30
Q

describe aneuploidy

A
  • Abnormal number of chromosomes in a cell
  • Nondisjunction during mitosis or meiosis
    • A chromosome may fail to separate during anaphase
    • Trisomy
      • Gain of extra chromosome
    • Monosomy
      • Loss of 1 chromosome
    • Nullisomy
      • Loss of both chromosomes
31
Q

describe polyploidy

A
  • Whole sets of extra chromosomes
  • Triploids (3n)
  • tetraploids (4n)
32
Q
A

Module 1 CB (18 decks)

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