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bisc202 > mitosis > Flashcards

mitosis Flashcards

1
Q

key rolls of cell division (2)

A
  1. reproducibility best distinguishes living things from non living
    2.continuation of life depends on cell division
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2
Q

asexual reproduction in euk vs prok

A

euk=mitosis
prok=binary fission

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3
Q

sexual reproduction in prok (3) *image in notes for clarification

A
  1. transformation– prokaryote
    takes up DNA found within the
    environment that has originated
    from other prokaryotes (antibiotic resistance)
    2.transduction– prokaryote is
    infected by a virus which injects
    short pieces of chromosomal
    DNA from one bacterium to
    anothe
    3.conjugation–dna is transferred between proks by means of sex pilus
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4
Q

chromatin vs chromosomes

A

chromatin=relaxed state, spends most time in this state
chromosomes=tightly wound, for cell division

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5
Q

which human cells dont have 46 chromosomes

A

sex cells

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6
Q

somatic cells vs gametic cells

A

somatic= non-reproductive, mitosis, 2 sets of chromosmes
gametic=reproductive cells, meiosis, 1/2 chromosmes of somatic

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7
Q

cohesins

A

chroms held together by assisatance of protein rings called cohesins

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8
Q

centromere

A

where the two sides of the chroms are most closely attached

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9
Q

2 proteins that help w packaging dna

A
  1. histones-dna gets wrapped around these but doesnt fuly condense
  2. condensins-protien rings that do the most for condensing dna just before cell division
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10
Q

subphases if interphase

A
  1. g1
  2. s
  3. g2

*cell grows in all three phases but chroms duplicated only in s phase

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11
Q

mitotic phase

A

cytokinesis+mitosis

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12
Q

mitotic spindles

A

=appartus of microtubules controllling the chroms movement during mitosis (includes centrosomes, spindle microtubules, and asters)

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12
Q

centrosome

A

-organelle that serves as a microtubule organizing centre (MTOC)
-replication leads to 2 sentrosomes that migrate to opposite ends of the cell as spindles grow out of them
-some spindles are long and make contact w chroms and some are short and make no contact w chroms

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13
Q

aster (astral microtubules)

A

-short microtubules
-connect proteins on inner surface of cell membrane
-dont know much abt these yet but so far a pretty minor role

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14
Q

kinetochore microtubules

A

=capture sister chromatids by binding to kinetochore proteins (that centre circle thing in chroms)

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15
Q

centrosome vs centromere

A

-The centromere is middle of chromosome that serves as the attachment point for spindle fibers (via the kinetochore) during cell division.
-the main microtubule organizing center (MTOC) of the cell. consists of two centrioles
centrosome duplicates before cell division, and each daughter cell inherits one centrosome

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16
Q

non-kinetochore microtubukes

A

aka polar microtubules, dont capture the sister chromatids, but they will help with the cell division process (he will address later in lecture)

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17
Q

gap pase leading into mitotic phase

A

=G2
-muclear enevelope intact and nucleoli present; centrosome is alrd duplicated; chromatin dupliacted during S-phase

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18
Q

prophase (early)

A

nucleolus disaooears; chromatin fibers become tightly coiled and condense to form chroms (which first becoe visible using light microscope); centrosomes move away from eachother as microtubules (mct) lenghten

19
Q

Prometaphase (late prophase)

A

nuclear envelope breaks down; chroms become sompletely condesned; mct (kinetochore and non) invade nuclear space

20
Q

metaphase

A

centrosomes are found completely opposite from eachother (held in place by astral mct); formation of spindle apparatus completed; chroms settle at metaphase (equatorial) plate

21
Q

anaphase

A

sister chromatids move to opposite poles of cell as kinetochore mct shorten’ non-kinetochore mct grow longer which helps elongate cell

22
Q

telophase

A

chroms decondense; nucleolus and nuclear enevelope reform;spindle mcts disapear; middle of cell starts pinching inwards and this is why the non-kin mct had to become longer to make space

23
Q

diploid cell with 6 choms at start of mitotic phase. determine # of chroms and sister chromatids at each phase (PMATC)

A

P: 6chroms, 12sis
M: 6chroms, 12sis
A: 12, 0
T: 12, 0
C: 6, 0

*once chroms seperate from its duplicated sis, they are no longer sisters. meaning when chroms are in unreplicated form we have no sisters (sisters work better together)

24
Q

cell cycle consists of 2 phases, what are they

A

interphase (90%) mitotic phase (10%)

25
Q

dna replication occurs during which phase in cell cycle

A

s phase

26
Q

a cell in G1 has 8 chroms and 1picogram of dna, in G2 this cell will have…

A

8 chroms and 2 picograms of dna

27
Q

cleavage furrow vs cell plate

A

cytokenisis in animal cells=cleavage
cell plate in plant cells

28
Q

binary fission

A

-in bacteria and archaea
- asexual reproduction
-dna replicates and cell elongates to seperate, no mitosis

29
Q

which checkpoint is the most important for most cells?

A

g1

30
Q

if a cell doesnt complete a checkpoint what happens? (be specific abt each checkpoint)

A
  • if g1 is not completed then cell enteres g0, aptosis if irreperable (likr dna not fixable), or stall
    -g2; cell may pause and repair or aptosis, or rarely, may enter arrest without going into aptosis
    -m is same as g2
31
Q

g1 checkpoint:

A

-dna is undamaged
-cell size is adequate
-enough nutrients
-social signals are present (external signals)

32
Q

g2 checkpoint:

A

-chroms replicated
-undamaged dna
-activated mpf present
(chroms and good dna leads to mpf activation)

33
Q

m checkpoint:

A
  1. chroms attached to spindle apparatus (between metaphase and anaphase)
  2. chroms properly seperated and mpf absent (between anaphase and telphase)
34
Q

which type of cells have the ability to exit g0 phase when needed?

A

eg) liver cells can divide when liver is damaged

35
Q

cyclins and cyclin-dependent kinases (cdks)

A

-2 regulating protiens in cell cycle control
-both form mpf which triggers a cells passgae past g2 checkpoint to m phase when enough is made
- levels of cyclin fluctates not cdk

36
Q

which phase is cyclin made in

A

late s phase

37
Q

internal “stop and go” signal

A

-mpf
-apc
-until all kinetochores are attached, anaphase-promoting complex (apc) stays inactive
- activated apc (past first m checkpoint.) triggers breakdown of securin and activated seperase to degrade cohesin so chromatids can sepreate

38
Q

Maturation-promoting factor (mpf)

A

-cyclin-cdk complex
-enough mpf triggers a cells passage past g2 checkpoint
-promotes mitosis via activation of various proteins like condensins to help further compact chroms before M
-mpf declines before anaphase (cyclin declines)

39
Q

external chemical factors that influence cell division

A

-growth factors=proteins released by certain cells that stimulate other cells to divide
eg) platlet-derived growth factor-stimulated division of human fibroblast cells in culture (controlled, lab settting)
- atleast 50 growth factors

*fibroblasts=cells responsible for making extracellular matrix and collagen

40
Q

external physical factors that influence cell division

A
  1. density dependant inhibtion (crowded cells stop dividing)
  2. anchorage dependence (must be attached to a substratum for division)

*cancer cells exhibit neither of these

41
Q

types of tumours

A

cancer cells proliferate (divide rapidly and in an uncontrolled manner)
1. benign
2. malignant (metastasizes)

42
Q

some differences between normal healthy cells and cancer cells

A
  • c cells dont exhibit density dependent inhibtion or anchorage dependence
    -c cells have loss of cell cycle function (proliferate)
    -c cells either dont repair or dont undergo apoptosis when theyre damaged or get old (p53 protein may be abnormal or inactive in c cells)
  • c cells have no adhesion molecs that keep them bonded to neighboring cells
    -c cells can metastasize
    -c cells do not develop into specialized cells
    -c cells undergo angiogenesis even when growth is unnecessary (healthy cells only do as part of normal growth and when new tissue is needed or to be repaired)
43
Q

andiogenesis

A

small tumour can appear and as it grows it can connect to blood supply by growing capillaries which supply the cells nutrients from blood and allow for the c cells to metastisize

44
Q

which protein check sif a cell is too damaged to repair –> undergoes apoptosis

A

p53

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