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general biology I > test 2: lecture 8 - cell division & dna replication > Flashcards

test 2: lecture 8 - cell division & dna replication Flashcards

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1
Q

somatic cells go through which process? mitosis or meiosis?

A

mitosis (ex: skin cells) - more common

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2
Q

sexual cells go through which process? mitosis or meiosis?

A

meiosis (ex: eggs, sperm)

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3
Q

who discovered DNA?

A

waston, crick and franklin

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4
Q

what is always the first step of mitosis or meiosis?

A

DNA replication

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5
Q

DNA replication

A
  • DNA unzips and gets copied
  • happens in nucleus
  • result: 2 identical copies of DNA
  • replication is semiconservative: 1 parent strand + 1 new strand
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6
Q

semiconservative model

A

two strands of the parental molecule seperate and each functions as a template for synthesis of a new, complementary strand

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7
Q

base pairing in DNA

A

adenine - thymine

guanine - cytosine

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8
Q

what does DNA copying start with?

A

RNA primer

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9
Q

in which direction does replication occur?

A

5’ to 3’ (nucleotides added onto 3’ end)

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10
Q

what enzyme helps DNA replication?

A

DNA polymerase

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11
Q

what is the mechanism that checks for & corrects mistakes?

A

mismatch repair

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12
Q

what are the 4 noncoding DNA sequences?

A
  • transcription/translation regulators
  • origins of DNA replication
  • centromeres
  • telomeres
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13
Q

what are telomeres?

A

special noncoding sequences added onto the end of eukaryotic chromosomes to protect them from being eroded

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14
Q

true or false? when eukaryotic cells divide, chromosomes get shorter

A

true - ends of chromosomes do not get fully replicated

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15
Q

facts about telomeres

A
  • do not contain genes
  • provide protective function by postponing erosion of genes located near ends of DNA molecules
  • shrink every time cell divides
  • proposed that shortening telomeres is connected to the aging process
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16
Q

what is the name of the special enzyme germ cells have and what does it do?

A

telomerase - catalyzes the lengthening of telomeres in eukaryotic germ cells

17
Q

cell cycle

A

G1, S, G2, mitosis

18
Q

what is interphase?

A

G1, S, G2

19
Q

what is the shortest phase of the cell cycle?

A

mitosis

20
Q

what happens during G1 and G2?

A

cells grows and makes proteins, organelles

21
Q

what happens during S phase?

A

only DNA replication going on

22
Q

G1 phase:

A
  • beginning of cell’s life
  • centrioles divide
  • cytokinesis
  • cell grows to full size
  • transcription and translation occur
  • DNA in single strands
23
Q

what causes the area around centrioles to be thicker than rest of cytoplasm? what is this called?

A

it’s called the centrosome - the helper proteins used by centrioles to help make spindle fibers cause this area to be thicker

24
Q

S phase:

A
  • DNA replicates - 2 double stranded DNA molecules
  • diploid and haploid
  • no more RNA (leftovers used for repairs)
  • centrosomes, centrioles still replicating
  • WITHOUT THIS PHASE CELLS CANT DIVIDE
25
Q

G2 phase:

A
  • well defined nucleus with membrane
  • centrosomes present, centriole copying complete
  • DNA has duplicated, but it in chromatin form
  • RNA transcribed to make proteins (spindle fibers)
  • leftover RNA used for repairs
26
Q

which is the most important permission point of the cell cycle?

A

G1 checkpoint

27
Q

centrosome

A

area for production and organization of microtubules

28
Q

true or false? plant has centrioles

A

FALSE - plant has centrosome, but no centrioles

29
Q

explain how centrioles and centrosome act in animal cells

A

centrioles replicate
centrosome divides
— result: two centrosomes (each with a pair of centrioles), move to opposite ends of nucleus, microtubules grow into spindle from each centrosome

30
Q

what are spindle fibers responsible for?

A

seperating the dividing cell and contents into new cell

31
Q

nerve and muscles cells are always in which phase?

A

G0

32
Q

liver cells are in which phase?

A

G0, but can be activated to come out of it

33
Q

true or false? cancerous cells obey checkpoint control

A

false

34
Q

what are check points controlled by?

A

regulatory protein - p53

35
Q

what is p53?

A

most important regulatory protein, classified as a tumor suppressor protein

36
Q

how does p53 fight cancer?

A

1- pause cell cycle and initiate DNA repair

2- if DNA cannot be repaired, it will induce apoptosis

37
Q

apoptosis

A

programmed cell death

38
Q

how can cells lead to cancer?

A

if a damaged cell does not undergo apoptosis and divides

general biology I (20 decks)

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