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Histology > Cytoskeleton and Cell Division > Flashcards

Cytoskeleton and Cell Division Flashcards

1
Q

what are the functions of the cytoskeleton

A
  • provide support for plasma membrane and organelles
  • intracellular movement/ transport of substances
  • cell locomotion
  • Mm contractions
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2
Q

what are the 3 main elements of the cytoskeleton

A

microfilaments, intermediate filaments, and microtubules

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3
Q

-what is the function of microfilaments

A

maintain cell shape and facilitates shape changes during movement

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4
Q

what are actin strands made of

A

G-actin subunits

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5
Q

what are protofilaments

A

when G-actin polymerizes

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6
Q

what makes up F-actin

A

2 protfilaments twisting together

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7
Q

what does filamin do

A

forms support meshwork under plasma membrane call cell cortex

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8
Q

what does the cell cortex do

A

prevents cell from deformaition

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9
Q

what are microfilaments made of

A

actin and myosin

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10
Q

what is required for movement of microfilaments with myosin

A

Ca and ATP

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11
Q

what cell types are intermediate filaments found in

A
  • (cyto)keratin
  • vimentin
  • desmin
  • neurofilament proteins
  • GFAP
  • lamin
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12
Q

where are keratin cells found

A

epithelial cells, forms tonofibrils

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13
Q

where is vimentin found

A

mesodermal cells of mesenchymal origin (endothelial cells, muscle, and neuroectodermal cells)

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14
Q

where is desmin found

A

unique to muscle cells, mesodermal origin

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15
Q

where are neurofilament proteins found

A

present in nerve cells

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16
Q

where are GFAP proteins found and what does it stand for

A
  • glial fibrillary acidic protein

- found in glial cells of nervous system

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17
Q

where is lamin found

A

forms layer of inside of nuclear membrane

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18
Q

what are microtubules made of

A

alpha and beta tubulin

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19
Q

what are the functions of microtubules

A
  • cell movement
  • maintenance of cell shape
  • intracellular transport of substances
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20
Q

how do microtubules move

A

via addition or subtraction of tubulin subunits from microtubules

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21
Q

what molecules attach microtubules to organelles

A

dynein and kynsein

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22
Q

how are microtubules stabilized

A

capping proteins

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23
Q

what inhibits microtubule polymerization and cell division

A

colchicine, vincristine and vinblastin

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24
Q

where are microtubules found

A
  • cilia and flagella
  • centrioles
  • basal bodies of cilia
  • mitotic spindles
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25
Q

what are axoneme

A

9 pairs of microtubules containing dynein arms arranged in a circle with central doublet in the middle

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26
Q

how is the central doublet connected to peripheral doublet

A

radial spokes

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27
Q

how are peripheral doublets connected to each other

A

nexin

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28
Q

where are axonemes found

A

cilia and flagella

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29
Q

where are centrioles located

A

in the centrosome near the nucleus and functions in cell division

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30
Q

what is a diplosome

A

centrioles orient at right angles to make a “T” shape

31
Q

what is a centriole made of

A

9 triplets of microtubules arranged in a cylinder

32
Q

how do movement of chromosomes occur in cell division

A

addition and subtraction of tubulin subunits and attachment of proteins to chromatids at the kinetochore

33
Q

what are the phases of mitosis

A

interphase, prophase, metaphase, anaphase, telophase

34
Q

what is interphase and what are the parts in it

A

time between divisions, G1, S, G2

35
Q

what occurs in G1

A

longest of cell phase, hypertrophy

36
Q

what happens in the S phase of interphase

A
  • replication of DNA prior to division
  • at beginning chromosome # is 2n at end it is 4n
  • following replication in S phase, each chromosome contains 2 chromatids connected by centromere
  • 2 diplosomes
37
Q

what happens in G2

A
  • preparation for mitosis

- synthesis of ATP and tubulin for mitotic spindle

38
Q

what happens in the M phase of the cell cycle

A

mitosis

  • 2 daughter cells form
  • nucleus divides (karyokinesis) followed by cytoplasmic division (cytokinesis)
39
Q

what do chromosomes look like during the S and M phases

A

chromosomes condense, become visible, look like coiled snakes

40
Q

what do chromosomes look like during G1 and G0

A

chromosomes exist in an unraveled mass

41
Q

what are facultative dividers

A

cells that retain capacity for division with proper stimulus

42
Q

what are terminally differentiated cells

A

cells that have lost the capacity to divide

43
Q

what happens in prophase

A

chromosomes visibly condense

  • microfilaments and microtubules of cytoskeleton disaggregate
  • centrioles migrate to poles of cell, form spindle apparatus with interpolar microtubules between them
44
Q

what happens in prometaphase/ late prophase

A

nuclear membrane and nucleoli disappear at end of prophase

- mitotic spindle attached to chromosomes at kinetochore

45
Q

what is the major distinction between prophase and prometaphase

A

the nuclear membrane does not exist in prometaphase

46
Q

what happens during metaphase

A

chromosomes line up along the equator

47
Q

what happens during anaphase

A

centromeres split apart, chromosomes migrate to opposite ends of the cell
- pulled by microtubules connecting centriole and kinetochore

48
Q

what happens in telophase

A
  • mitotic spindle disaggregates
  • nuclear envelope reassembles, nucleoli reappear,
  • plasma membrane forms either cleavage furrow (animal cell) or cytokinesis ( plants)
49
Q

what is the mitotic index

A

a tool used to describe proportion of cells in a tissue in mitosis at any given time

50
Q

what is a normal mitotic index

A

1 or less

51
Q

what happens in meiosis

A

chromosomal duplication followed by two consecutive cell divisions

52
Q

what are the phases of the first meiotic division

A

prophase, metaphase, anaphase, and telophase

53
Q

what does the first meiotic division result in

A

two daughter cells

54
Q

how does meiosis differ from mitosis

A
  • in prophase I, homologous pairs of chromosomes form tetrads, with exchange of chromatin via crossing over. it results in hybrid chromatids different from parents
  • centromeres do not split during anaphase I
55
Q

when does crossing over occur

A

only in prophase I

56
Q

what happens before the second meiotic division

A

brief interphase II with no replication of DNA

57
Q

what happens in each phase of the second meiotic division

A

prophase II- no crossing over
anaphase II- centromeres split
telophase II- cytokinesis yields four haploid gametes

58
Q

how many viable gametes does spermatogenesis produce

A

3 or 4

59
Q

how many viable gametes does oogenesis create

A

1

60
Q

what are the non-functional gametes in oogenesis called

A

polar bodies

61
Q

when does spermatogenesis begin

A

at puberty

62
Q

when does oogenesis begin

A

during fetal development

63
Q

when do female germ cells enter prophase I

A

about 5th month of gestation during fetal development then they stop

64
Q

what are the triggers for apoptosis

A
  • programmed cell death
  • some cells have finite life spans
  • growth and regression of ovarian follices
  • destruction of virus or tumor cells
  • clonal deletion
65
Q

what is clonal deletion

A

in thymus it is the removal of t-cells that react to self molecules

66
Q

describe what happens in apoptosis

A
  • begins with condensation of nuclear chromatin and shrinkage of nucleus
  • cell swells
  • lysosomes release catalytic enzymes into cytoplasm
  • autolysis
  • cell becomes bright pink
  • caspace cascade
67
Q

what is pyknosis

A

shrinkage of nucleus

68
Q

why does the cell swell in apoptosis

A

because the mitochondrial membrane is disrupted so it cannot produce ATP for the sodium potassium pump and sodium gets stuck inside the cell and water rushes in

69
Q

why does the cytoplasm of the cell become pink in apoptosis

A

because the enzymes from lysosomes decrease the pH and denature proteins

70
Q

how can you decipher a pyknotic nucleus

A

its very dark black from condensation of chromatin

71
Q

what is the caspace cascade

A

enzymes that trigger the activation of the next to destroy the cell in apoptosis

72
Q

what is karyolysis

A

chromatin in nucleus begins to degenerate

73
Q

what is karyorhexis

A

nuclear material begins to fragment and nuclear membrane disintegrates

74
Q

what are apoptotic bodies

A

fragmented nuclear debris

Histology (27 decks)

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