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BIOLOGY 130 > Unit 9 - Mitosis, Meiosis, & Cell Cycle > Flashcards

Unit 9 - Mitosis, Meiosis, & Cell Cycle Flashcards

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1
Q

combos of chromosomes in Meiosis =

A

2^n where n = haploid #

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2
Q

32F

A

-gene regulatory protein that binds to promoters of many genes that encode for S-phase re-entry

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3
Q

4 Classes of Cyclins which drive the cell cycle

A
  1. G1-Cdk –> helps with passage through the restriction point
  2. G1/S-Cdk –> commits cells to DNA replication
  3. S-Cdk –> carries out replication
  4. M-Cdk –> promotes events of mitosis (MPF)
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4
Q

Advantages of Sexual Reproduction

A
  • allows natural selection against deleterious alleles of genes
  • species better equiped to survive environmental changes
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5
Q

Anaphase (Mitosis)

A

-sister chromatids seperate

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6
Q

Anaphase 1

A

-homologs begin to seperate

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7
Q

Anaphase 2

A

-sister chromatids begin to seperate

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8
Q

Apoptosis

A
  • programmed cell death
  • getting rid of unwanted cells
  • carried out by caspase family of enzymes
  • present in all cells as inactive precursors
  • all or none signal
  • regulated by Bcl-2 family of proteins
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9
Q

Asexual Reproduction

A

-organism well adapted to its environment can ‘clone’ itself at a rapid rate

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10
Q

Cancer can be a result of…

A

-failure to respect checkpoints

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11
Q

Chromosomes become visible when…

A

-cells are about to divide

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12
Q

Cyclin

A
  • regulatory subunit

- levels oscillate throughout the cell cycle

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13
Q

Cyclin-Dependent Kinase (Cdk)

A
  • catalytic subunit
  • transfers phosphate from ATP to amino acids on target proteins
  • not active unless bound to cyclin partner
  • levels not constant
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14
Q

Cytokinesis in Animal Cells

A
  • ring of actin filaments under plasma membrane are involved

- associated with motor proteins (myosin)

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15
Q

Cytokinesis in Plant Cells

A
  • microtubules and proteins define and organize the regions where the new cell membrane and wall form
  • vesicles (from Golgi) arrive, carrying polysaccharides & glycoproteins to lay down matrix for the new cell wall
  • later cellulose fibres are laid down to complete the wall
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16
Q

Eukaryotic Chromosomes

A
  • multiple linear chromosomes housed in nucleus
  • two copies (each) essential for survival
  • highly variable in number
  • complex packaging of DNA
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17
Q

G1 Phase

A
  • “gap 1”, most of cell’s growth occurs here

- part of interphase

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18
Q

G1/S Checkpoint: Restriction Point

A
  • discovered in yeast
  • integration of external and internal signals
  • inappropriate ‘start’ signals is often associated with answer cells
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19
Q

G2 Phase

A
  • “gap 2”
  • cell completes preparations for mitosis
  • chromosomes start to condense
  • spindle apparatus starts to form
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20
Q

G2/M Checkpoint

A

Checking for internal issues

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21
Q

Growth Factors

A
  • growth often coupled with cell division

- signals exist that negatively regulate growth

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22
Q

How can the Cell Cycle be ‘paused’?

A
  1. Cdk inhibitors can block entry to S phase
  2. inbition of activating phosphatase blocks entry to mitosis
  3. inhibition of APC activation delays exit from mitosis
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23
Q

How can we regulate Cdk activity?

A
  1. change the levels of cyclin partner: increase activity = increase cyclin expression
  2. addition/removal of inhibitory phosphate groups: increase = remove phosphate (activates phosphatase)
  3. presence/absence of inhibitory protein: increase = Cdk inhibitors not bound to cyclin-Cdk
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24
Q

How do we inactivate Cdk activity?

A

-targeted destruction of cyclin

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25
Q

Interphase (Mitosis)

A
  • 90% of a proliferating cell’s time
  • cell grows by producing proteins & organelles
  • copies chromosomes and prepares for cell division
26
Q

Interphase (Meiosis)

A

-chromosomes are replicated but remain as chromatin (not condensed)

27
Q

Leland Hartwell

A

-START gene, checkpoint concept

28
Q

M Phase

A
  • mitosis & cytokinesis
  • subdivided according to state of chromosomes
  • chromosomes finally condensed enough to become visible at prophase
29
Q

Meiosis

A
  • division of genetic material to produce daughter cells with half hereditary material found in parent cell
  • involved in production of gametes
  • basis of sexual reproduction & genetic inheritance
30
Q

Meiosis produces cells which have…

A
  • different combo. of chromosomes
  • different complement of genes
  • offspring which are genetically distinct from each other and their parents
31
Q

Metaphase (Mitosis)

A

-chromosomes migrate to the ‘equator’ of the cell –> metaphase plate

32
Q

Metaphase 1

A

-tetrads migrate to the metaphase plate

33
Q

Metaphase 2

A

-chromosomes line up

34
Q

Metazoans

A

-many cell divisions required to generate new organism from fertilized egg

35
Q

Mitogens

A

-push cells past the G1/S restriction point

36
Q

Mitosis

A
  • division of genetic material that produces daughter cells genetically identical to parent cell
  • usually accompanied by cytokinesis
37
Q

Mitosis vs Meiosis 1 (differences)

A

Mitosis: homologs line up independently, each cell gets same genes
Meiosis 1: homologs line up in pairs, positioning is random

38
Q

Mitosis-Promoting Factor (MPF)

A
  • discovered in mammalian cells
  • induces mitosis in all eukaryotic cells
  • hetero dimeric protein
39
Q

oncogenes/oncoproteins

A

-mutated versions of normal genes/proteins involved in driving cell division/proliferation

40
Q

p53

A
  • detects DNA damage at G1/S checkpoint

- leads to synthesis of inhibitor of G1/S-Cdk and S-Cdk

41
Q

Prophase 1

A
  • chromosomes condense and nuclear envelope breaks up
  • spindle forms and synapsis of homologs occurs
  • crossing over of non-sister chromatids, recombo. of genes
42
Q

Prophase 2

A

-spindle apparatus forms

43
Q

Rb (retinoblastoma) protein

A
  • binds to E2F during G1
  • blocks transcription of S-phase genes
  • blocks cell cycle progression
44
Q

S Phase

A
  • “Sythesis” phase
  • DNA copied here
  • chromosomes attached at centromeres, still fully extended
45
Q

Sexual reproduction involves both…

A
  1. haploid cells and

2. diploid cells

46
Q

Sir Paul Nurse

A

-cyclin-dependent kinase

47
Q

Sister chromatids

A
  • replicated homolog

- one chromosomes consisting of 2 sister chromatids

48
Q

Spindle Checkpoint

A

Metaphase –> Anaphase

49
Q

Telophase & Cytokinesis (Mitosis)

A
  • nuclear envelope re-forms

- spindle apparatus disintegrates

50
Q

Telophase 1 & Cytokinesis

A
  • chromosomes move to the opposite sides of cell

- cell divides

51
Q

Telophase 2 & Cytokinesis

A
  • chromosomes separate

- cells divide

52
Q

terminally differentiated

A

-when cells become highly specialized and can no longer divide

53
Q

Tim Hunt

A

-discovery of cyclins (sea urchins)

54
Q

Tumor Suppressors

A
  • link cell cycle to DNA damage
  • proteins that detect DNA damage and initiate events that halt the cell cycle
  • typically transcription factors that drive expression of genes that code for proteins which inhibit Cdks
55
Q

Unicellular

A

generates complete new organism

56
Q

what 2 transient cytoskeletal structures are required for cell division in eukaryotes?

A
  • microtubules of the mitotic spindle

- actin and myosin filaments of the contractile ring

57
Q

What mistakes can occur in meiosis?

A

-improper distribution of chromosomes to each daughter cell - “non-disjuction” = gametes with abnormal # chromosomes –> “aneuploidy”

58
Q

When is the cell ready to complete mitosis?

A

-when all chromosomes are properly attached to spindles

59
Q

When should a cell divide?

A

when it receives an external signal

60
Q

When should a cell undergo mitosis?

A
  • when the DNA is properly replicated

- when no DNA is damaged

61
Q

where does genetic variability occur in meiosis?

A
  1. recombo. during prophase 1
  2. independent assortment of homologs during meta/ana/telophase of meiosis 1
  3. independent assortment of chromatids during meta/ana/telophase of meiosis 2

BIOLOGY 130 (11 decks)

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