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biology 1001 > cycle 2 > Flashcards

cycle 2 Flashcards

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1
Q

what phase of the cell cycle do most cells stay in?

A

G1 and G0, only cycle if they need to divide

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2
Q

cell cycle of early embryonic cells

A

S phase and mitosis (takes around 30 min)

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3
Q

cell cycle of later embryonic cells

A

G1, S, G2, mitosis

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4
Q

G1

A

period of cell growth before DNA replicates, when cell responds to signals to ensure entry to program differentiation

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5
Q

S

A

period when DNA replicates and chromosomal proteins are duplicates

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6
Q

G2

A

period after DNA replicates, cell prepares for division

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7
Q

mitosis

A

prophase, prometaphase, metaphase, anaphase, telophase

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8
Q

why do cells divide?

A

multicellular growth, tissue repair, regeneration

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9
Q

why is cell division important?

A

cells cannot continue to grow larger and larger because then the volume of the cell increases faster than the SA (SA can’t reach the demands of the cell)

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10
Q

cell cycle checkpoints

A

G1S, G2M, M

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11
Q

G1S checkpoint

A

ensures that there is no damage to the DNA, ensures that there are enough proteins and enzymes for division

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12
Q

G2M checkpoint

A

checks to see if DNA is fully replicated/ if it is damaged, ensures that the cell is large enough and has enough nutrients for mitosis

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13
Q

M checkpoint (metaphase)

A

ensures proper alignment of chromosomes on the metaphase plate, ensures that chromosomes are properly attached to spindle fibres at their centromeres

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14
Q

what are the 2 results of cell cycle checkpoints?

A

fixes the problem or cell death (apoptosis)

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15
Q

what regulates the cell cycle?

A

proteins (positive/negative regulators, balance of the two keeps the cell cycle in check)

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16
Q

how do bacteria/archaea replicate?

A

binary fission

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17
Q

chromosome

A

packaged chromatin (DNA and proteins packaged together)

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18
Q

of chromosomes =

A

of centromeres

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19
Q

of chromatids =

A

of DNA helices

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20
Q

interphase

A

G1, S, G2 (nuclear membrane is still intact)

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21
Q

events of mitosis

A

both nuclear (DNA changes) and cytoplasmic (cytoskeleton, organelles, cell shape)

22
Q

kinetochores

A

proteins that mediate chromatin/cytoskeleton connection when sister chromatids split

23
Q

prophase

A

chromosomal condensation, accomplished by histones (4) to make nucleosomes (pack together to form solenoids), nucleolus breaks down, centrioles travel to opposite poles and spindle fibres assemble

24
Q

prometaphase

A

nuclear envelope breaks down, centrosomes attach DNA to centromere, kinetochores are formed and spindle fibres attach

25
Q

metaphase

A

movement of sister chromatids to metaphase plate (accomplished by kinetochore microtubules), align in centre of cell, time when karyotypes are taken

26
Q

anaphase

A

when each chromatid becomes a chromosome, pulled apart to opposite poles

27
Q

telophase

A

nuclear envelope reappears, chromosomes decondense, spindle fibres disappear, transcription resumes

28
Q

cytokinesis

A

splitting of cytoplasm (cells), animals (furrowing of cell to divide-use of actin on outside), plants (division by cell plate-use of vesicles)

29
Q

cyclins

A

activate/deactivate kinases that control the cell cycle (at checkpoints)

30
Q

CDKs

A

cyclin-dependant protein kinases (assembles with cyclins to create complexes which regulate cell cycle)

31
Q

cyclin-CDK complex formation

A

cyclin binds to CDK, cyclin-CDK complex is phosphorylated, activated cyclin-CDK complex phosphorylates target protein, phosphorylated target protein changes conformation into active form (moves cell into the next stage of the cell cycle)

32
Q

are cyclin-CDK complexes positive/negative regulators?

A

positive (also include enzymes and transcriptional regulators)

33
Q

p53

A

guardian of the genome that detects/regulates DNA damage, majority of cancers have a non-functional p53

34
Q

p21

A

cyclin-CDK inhibitor to prevent progression past G1S checkpoint (repair or die)

35
Q

Rb (retinoblastoma protein)

A

inhibits progression past G1S checkpoint unless it is phosphorylated to release E2F

36
Q

what type of regulators are p53, p21, and Rb?

A

negative

37
Q

how does p53 work?

A

attached to a promoter upstream from DNA damage to activate the p21 gene, p21 inhibits cyclin-CDK by not allowing it to phosphorylate proteins

38
Q

p53 regulation pathways

A

if DNA damage can be repaired (positive pathway, activation of cyclin-CDK), if DNA damage cannot be repaired (negative pathway, apoptosis)

39
Q

meiosis I (reductional)

A
  • prophase I: pairing of homologous chromosomes (at synapsis, tetrad formed), recombination (crossing over) ensures genetic diversity
  • metaphase I: tetrads line up at metaphase plate
  • anaphase I: homologous chromosomes are pulled apart (centromere is not separated, sister chromatids remain intact)
  • telophase I: proceeds to mitosis II (cytokinesis)
40
Q

meiosis II (equational)

A

separation of sister chromatids to produce 4 unique haploid cells

41
Q

recombination

A

homologous chromosomes pair, exchange segments (at chiasma)- have to be in close proximity, sister chromatids are no longer identical (ensures genetic diversity)

42
Q

linked genes

A

genes that are likely to be inherited together (close in proximity)

43
Q

sources of genetic diversity in meiosis

A 
independent assortment (metaphase I, way that tetrads align is random),
lining up of sister chromatids (metaphase II, randomly line up), random fertilization (zygotes bring DNA from 2 different parents into same cell)
44
Q

aneuploidy

A

cells with abnormal numbers of chromosomes after meiosis, occurs due to non-disjunction

45
Q

non-disjunction

A

can occur during meiosis I (homologous chromosomes don’t separate) or meiosis II (sister chromatids don’t separate)

46
Q

trisomy 21

A

down syndrome

47
Q

trisomy 13

A

patau syndrome

48
Q

trisomy 18

A

edward’s syndrome

49
Q

why is aneuploidy increasingly common as the age of the mother increases?

A

oocytes are produced in the fetus and are arrested in meiosis I and sit around and accumulate mutations until fertilized

50
Q

animal life cycle

A

gametes arise by meiosis, zygote divides by mitosis (lives in diploid phase)

51
Q

plant/fungi life cycles

A

gametes arise by mitosis, spores (haploid) are formed by meiosis (have alternate generations, diploid-sporophytes and haploid-gametophytes)

52
Q

some fungi/algae life cycles

A

gametes arise by mitosis, zygote divides by meiosis (have alternate generations, dominant is haploid phase)

biology 1001 (11 decks)

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