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biology 1001 > cycle 2 > Flashcards

cycle 2 Flashcards

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
metaphase
movement of sister chromatids to metaphase plate (accomplished by kinetochore microtubules), align in centre of cell, time when karyotypes are taken
26
anaphase
when each chromatid becomes a chromosome, pulled apart to opposite poles
27
telophase
nuclear envelope reappears, chromosomes decondense, spindle fibres disappear, transcription resumes
28
cytokinesis
splitting of cytoplasm (cells), animals (furrowing of cell to divide-use of actin on outside), plants (division by cell plate-use of vesicles)
29
cyclins
activate/deactivate kinases that control the cell cycle (at checkpoints)
30
CDKs
cyclin-dependant protein kinases (assembles with cyclins to create complexes which regulate cell cycle)
31
cyclin-CDK complex formation
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
are cyclin-CDK complexes positive/negative regulators?
positive (also include enzymes and transcriptional regulators)
33
p53
guardian of the genome that detects/regulates DNA damage, majority of cancers have a non-functional p53
34
p21
cyclin-CDK inhibitor to prevent progression past G1S checkpoint (repair or die)
35
Rb (retinoblastoma protein)
inhibits progression past G1S checkpoint unless it is phosphorylated to release E2F
36
what type of regulators are p53, p21, and Rb?
negative
37
how does p53 work?
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
p53 regulation pathways
if DNA damage can be repaired (positive pathway, activation of cyclin-CDK), if DNA damage cannot be repaired (negative pathway, apoptosis)
39
meiosis I (reductional)
- 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
meiosis II (equational)
separation of sister chromatids to produce 4 unique haploid cells
41
recombination
homologous chromosomes pair, exchange segments (at chiasma)- have to be in close proximity, sister chromatids are no longer identical (ensures genetic diversity)
42
linked genes
genes that are likely to be inherited together (close in proximity)
43
sources of genetic diversity in meiosis
``` 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
aneuploidy
cells with abnormal numbers of chromosomes after meiosis, occurs due to non-disjunction
45
non-disjunction
can occur during meiosis I (homologous chromosomes don't separate) or meiosis II (sister chromatids don't separate)
46
trisomy 21
down syndrome
47
trisomy 13
patau syndrome
48
trisomy 18
edward's syndrome
49
why is aneuploidy increasingly common as the age of the mother increases?
oocytes are produced in the fetus and are arrested in meiosis I and sit around and accumulate mutations until fertilized
50
animal life cycle
gametes arise by meiosis, zygote divides by mitosis (lives in diploid phase)
51
plant/fungi life cycles
gametes arise by mitosis, spores (haploid) are formed by meiosis (have alternate generations, diploid-sporophytes and haploid-gametophytes)
52
some fungi/algae life cycles
gametes arise by mitosis, zygote divides by meiosis (have alternate generations, dominant is haploid phase)

biology 1001 (11 decks)

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