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Introduction to cell biology uottawa > chapter 2 > Flashcards

chapter 2 Flashcards

1
Q

cytoskeleton is made of 3 components within the cytoplasm:

A

microtubules
microfilaments
intermediate filaments

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2
Q

cytoskeleton participates in:

A

mechanical( physical forces and changes in the mechanical properties of cells and tissues contribute to development, cell differentiation, physiology, and disease.)

structural
transport
motility
signalling functions

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3
Q

what is responsible for the maintenance and modifications of the animal cell’s shape and why?

A

it is the cytoskeleton

because the animal cells lack cell walls

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4
Q

what are pseudopodia?

A

these are temporary cytoplasmic projections visible in amoeboid movements

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5
Q

how plants can maintain their rigid shape?

A

maintained by the cell wall !

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6
Q

what are microtubules?

A

thick hollow(empty) rod(barre en francais) composed of tubulin proteins

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7
Q

tubuline is what type of structure?(trimer or dimer)

and made of what types of tubuline?

A

dimer

alpha-tubuline
beta-tubuline

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8
Q

a microtubule can grow and shrink in lingth from ….which end? what is the name of this process?

A

from the + end

polymerisation

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9
Q

the - end of the microtubule is attached to the……

A

centrosome

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10
Q

the + and - ends means that they are charged?

A

non

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11
Q

the main functions of the microtubules:

A

maintenance of cell shape (compression-resisting girders(poutres)

cell motility( for cilia or flagella)

chromosome movements in cell division

organelle movements

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12
Q

which tubulin is on which side of the end?

A

tubuline alpha on the - end

tubuline beta on the + end

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13
Q

true or false

both beta and alpha tubuline cand bind GTP?

A

yes

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14
Q

what happens to the GTP linked to both of the tubulins?

A

the GTP linked to alpha tubuline stays in form of ATP

the GTP linked to beta tubuline can be hydrolyzed en GDP

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15
Q

how the tubulins are added to each other?

A

the alpha tub binds to the beta tube forming a dimer.

and a dimer will to another dimer like this: the + end of one dimer will link to the - end of an another dimer

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16
Q

how the depolymerisation is made?

A

both tubuline are linked to an GTP. this is a very strong link. So, to do it, the GTP from the beta-tubuline has ti be hydrolyzed and the interaction between the beta and alpha tubulin becomes weak and easier to break

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17
Q

the rate of GTP hydrolysis on which depend the polymerisation and depolymerization depends on….. and why?

A

on the rate of addition of dimers tubulins

the more we have of dimers, the more they will link together forming the microtubules and stabilizing them if needed(not depolymerization), but if there is a lack of dimers, then the dimers on the microtubules will depollarize. faster on slower, the faster we will be able to add them = polymerization et l’inverse aussi

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18
Q

the microtubules are able to move what kind of structures inside the cytosol?

A

organelles

vesicles

enzymes

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19
Q

mouvments of the structures in the cytosol are caused by what? what types of energy?

A

motor proteins powered by ATP

it converts chemical energy to mechanical energy

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20
Q

give examples of motor proteins

A

kinesin

dynein

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21
Q

at which end it moves the cargo the kinesin?

A

towards the + end of the microtubules

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22
Q

towards which end it moves the cargo the dynein?

A

towards the - end of the microtubules

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23
Q

is it possible for a single vesicle to have both proteins(kinesine and dynein) at the same time? but…

A

yes

but only one will attach to the microtubule depending towards wich end the vesicle has to go

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24
Q

what do microtubules during cell division? and they radiate from where?

A

they are involved in the separation of chromosomes during mitosis.
from the centrosome

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25
Q

in which cells are the centrosome present? and where in the cell?
what is its function?

A

in animal cells

near nucleus

function: MTOC: microtubule -organizing center

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26
Q

the centrosomes are made of 2 components? which are composed of?

A

centrioles

9 microtubules triplets(9+0)

27
Q

after mitosis, what happens to centrioles?

A

it separates them to each daughter cell

28
Q

what means the arrangement 9+0

A

1 centriole is made of 9 triplets of microtubules

the 0 is the number of microtubules that we can see inside the center of the centriole

29
Q

who is long and short? cilia and flagella?

A

flagella long

cilia short

30
Q

both cilia and flagella are what? and made of what?

and their function?

A

are appendages in eukaryotic cells

made of microtubules

function: for locomotion, move around the fluid and feed(cilia only not flagella)

31
Q

both flagella and cilia have a core named….

A

axoneme

32
Q

the axoneme is made of what type of arrangement and explain it
and it is covered by….

A

9+2

9 outer doublet microtubules

2 inner single microtubules

the axonema is covered by the plasma membrane

33
Q

the sliding of microtubules onto each other depends on which motor protein?

A

dynein

34
Q

during infection, sars-cov 2 causes what?

A

losses/shortening of cilia(axoneme) in trachea epithelial cells
misorientation of the basal body???demande prof

35
Q

if the % of ciliated area decreases, the means clearance of viral particles………

A

decreases

36
Q

La position de alpha et beta dans le dimère?

A

Beta en haut vers le +end et alpha en bas du dimère vers le - end

37
Q

what are microfilaments?composed of what?

A

thin filament composed of actin proteins acting alone or with myosin to cause cell contraction

38
Q

what is the structure of microfilaments?

A

double chain of actin subunits(2 intertwined strands of actin)

39
Q

function of microfilaments

A

resist compression

maintains the shape of the cell(the cortex: thin region directly beneath the plasma membrane)

interact with a protein myosin to cause muscle cells contraction

cytoplasmic streaming in plant cells

cell motility(as in amoebid movements)

division of animal cells

40
Q

the sliding of microfilaments(thin) into each other is powered by the

A

myosin

41
Q

donne l’ordre croissant, de la plus petite longeur vers la plus grande, des intermediate filaments, microtubules, microfilaments

A
  1. plus courte : microfilament
  2. intermediate filament
  3. microtubules(le plus long)
42
Q

what are intermediate filaments?

A

Strong and flexible filaments of intermediate size that provide mechanical support of the cell against physical stress(pressure)

43
Q

intermediate filaments are only found in the cells of some

A

animal, including vertebrates

ex: keratin found in epithelium, scales, hair, nails, feathers, horns, claws, hooves, skin

44
Q

who has a more permanent structure? microtubules, microfilaments or intermediate filaments?

A

intermediate filaments (not disassembled and reassembled as much as microtubules and microfilaments

45
Q

function of intermediate filaments

A

can bear tension(like microfilaments)

maintain shape of the cell and the nucleus(nuclear lamina)

fix the position of organelles

46
Q

intermediate filaments are made of what?

A

keratin proteins and others proteins

47
Q

plasmodesmata is found

A

ONLY in plants

48
Q

neighbouring cells of multicellular organisms ….. and …..to one another

A

adhere

communicate

49
Q

in plants, neighbouring cells are connectec by cytoplasmic channels called

A

plasmodesmata

50
Q

what does plasmodesmata?

A

it goes through the cell walls, making the membrane continuous between cells
letting then many substances to pass through to another cell

51
Q

in animals, there are 3 types of cell junctions

A

tight junctions

desmosomes

gap junctions

52
Q

what are tight junctions

A

plasma membranes of adjecent cell are bound together by proteins

53
Q

function of tight junctions

A

prevents leakage of fluid through the epithelium layers

this is impermeability

54
Q

give where we could find tight junctions?

A

epithelial cells such as skin cells and enterocytes(epithelial cell of intestines) or endothelial cells such as blood vessels cells

55
Q

what are the components of a tight junctions and they differ in what?

A

occludin

claudin

these 2 differ in their transmembrane domain

56
Q

what are desmosomes?

A

anchors adjacent cells together through transmembrane proteins (that velong to the cadherins family) that are linked to the intermediate filaments

57
Q

function of desmosomes

A

keep adjacent cells tight together, especially in tissues that can stretch like myocyte(muscle cell)

58
Q

cadherins of desmosomes can attach to what inside the cell?

A

intermediate filaments

59
Q

who is similar to plasmodesmata(in plants)?

A

gap junctions(animals)

60
Q

gap junctions are made of what?

A

6 proteins (connexins) form a channel and allow the communication of adjacent cells

61
Q

function of gap junctions

A

allow communication between animal cells

letting thorugh ions and small molecules such as amino acids, sugars

coordination of their contraction with the molecules that they let through

62
Q

where we could find gap junctions?

A

heart muscles cells

63
Q

what is a connexon

A

is made of 2 pairs of 6 connexins and this represents the gap junctions between 2 cells

connexons is a link between 2 cells that allow molecules to pass-through

Introduction to cell biology uottawa (2 decks)

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