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BIOL 1020 > Lecture 17-19: Cell Division > Flashcards

Lecture 17-19: Cell Division Flashcards

1
Q

three reasons why cells divide:

A

reproduction
growth of an organism
repair/replacement of lost cells

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2
Q

the three broad categories cells can be grouped into based on their involvement in the cell cycle:

A
  1. Cells that do not cycle, but stay in a resting state (G0)
  2. Cells that normally do not divide, but can be induced to if needed
  3. Cells that divide regularly
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3
Q

what is a cell’s genetic information called?

A

genome

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4
Q

what is DNA packaged into?

A

chromosomes

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5
Q

chromatin (what makes up chromosomes) is composed of what two things:

A

1 DNA molecule and associated proteins (histones)

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6
Q

______ contain several hundred to thousand genes:

A

chromosomes

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7
Q

what is the actively expressed part of the chromosome? (i.e when cell is not dividing)

A

euchromatin

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8
Q

what are somatic cells?

A

cells that aren’t gametes

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9
Q

how many chromosomes are in human somatic cells?

A

46 chromosomes (2 sets of 23)

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10
Q

cell division results in genetically identical ________

A

daughter cells

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11
Q

a chromosome has a constriction called the _____

A

centromere

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12
Q

what is the centromere composed of?

A

repetitive sequences in the DNA

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13
Q

how are sister chromatids held together?

A

by cohesion proteins

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14
Q

______ separates the sister chromatids into 2 chromosomes and distributes one to each daughter cell

A

mitosis

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15
Q

what separates the cytoplasm?

A

cytokinesis

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16
Q

cell cycle = ?

A

time it takes from one cell division event to the next

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17
Q

the five stages of mitosis:

A

prophase
prometaphase
metaphase
anaphase
telophase
cytokinesis

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18
Q

actin microfilaments and mysoin are used in animal cells for what?

A

cytokinesis: they form a ring in the cytoplasm, which contracts using ATP -> making a cleavage furrow (like a drawstring bag!)

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19
Q

do plant cells have a cleavage furrow?

A

No!

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20
Q

what do plant cells use instead of a cleavage furrow?

A

form a cell plate (using vesicles to deliver materials) in between cell walls (made of carbohydrates/cellulose) which then cuts the cell in half and separates the cells

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21
Q

what is binary fission?

A

a form of asexual reproduction in prokaryotes

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22
Q

how is the DNA replicated using binary fission in prokaryotes?

A

begins replicating DNA from a single point in the circular DNA

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23
Q

what is the origin of replication?

A

the original point where DNA is replicated in prokaryotes using binary fission

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24
Q

is mitosis possible without cytokinesis?

A

yes! results in one huge cell

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25
Q

can cells divide at different rates within the organism?

A

yes! it all depends on cell function and location (ex. skin cells divide all the time, liver cells cand divide but only when needed)

26
Q

three main checkpoints in the cell cycle control system:

A

G1, G2, M

27
Q

why do we have checkpoints in the cell cycle?

A

to make sure everything passes certain conditions before the cycle continues! (i.e to catch mistakes!)

28
Q

the cell cycle control system is regulated by ____ and ________

A

cyclins and cyclin-dependant kinases

29
Q

what are cyclins?

A

proteins with fluctuating concentrations within the cytoplasm

30
Q

when do cyclins attach to cyclin-dependant kinases to form complexes?

A

if the concentration of cyclin is high enough

31
Q

why do cyclins attach to cyclin-dependant kinases to form complexes?

A

the kinase activates other proteins, causing the cell to proceed in the cycle!

32
Q

when is cyclin degraded (inactivating the kinase)?

A

at the end of the cycle

33
Q

what are the three parts of the maturation-promoting factor (MPF)?

A

a kinase, cyclin and a phosphate group

34
Q

when does the G1 checkpoint occur?

A

before the S phase

35
Q

which cells don’t pass the G1 checkpoint?

A

neurons and non-dividing cells

36
Q

when does the G2 checkpoint occur?

A

before mitosis

37
Q

which checkpoint interacts with MPF?

A

G2 checkpoint

38
Q

when does the M checkpoint occur?

A

during metaphase

39
Q

what is aneuploidy?

A

incorrect number of chromosomes

40
Q

what causes cancer?

A

when a group of cells uncontrollably divide

41
Q

what does it mean when a tumor is benign?

A

when abnormal cells cant spread, easily removable by surgery

42
Q

what does it mean when cells are malignant?

A

the cells have enough mutations that they can spread throughout the body, resulting in cancer

43
Q

basic explanation of the Hershey and Chase experiment:

A

showed that the phage T2 DNA was the mechanism for the virus to reprogram host cells, they saw that the DNA entered the cell but the protein remained external

44
Q

DNA has _______ bases

A

nitrogenous

45
Q

what are the two purine bases?

A

adenosine (A) and guanine (G)

46
Q

what are the two pyrmidine bases?

A

thymine (T) and cytosine (C)

47
Q

what kind of bonds hold DNA strands together?

A

hydrogen bonds

48
Q

each DNA strand serves as a template to make _____ new complementary strands

A

two

49
Q

prokaryotes have ______ DNA

A

circular

50
Q

where does replication begin in prokaryotes?

A

origins of replication (ORI’s), a specific sequence of DNA nucleotides

51
Q

_______ is the main enzyme that catalyses the DNA synthesis

A

DNA polymerase III

52
Q

DAN synthesis is only completed in what direction?

A

5’ to 3’

53
Q

when the lagging strand is sythesised, it creates fragments called…?

A

okazaki fragments

54
Q

what is the solution for staggered ends in DAN replication?

A

telomeres!

55
Q

what is a telomere?

A

a short, repeated DNA sequences and specific proetins that protect the ends of chromosomes

56
Q

germline cells that produce gametes make an enzyme called ______ which extends the telomeres to 100% length

A

telomerase

57
Q

What happens when incorrect nucleotides are missed in DNA replication?

A

mismatch repair

58
Q

can errors happen after replication?

A

yes! examples include UV radiation, cigarette smoke and other chemicals

59
Q

what are histones?

A

positively charged proteins that initially pack the chromatin

60
Q

four forms of chromatin during cell division:

A

chromatin -> heterochromatin -> euchromatin -> chromosomes

BIOL 1020 (10 decks)

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