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
in which cells are the centrosome present? and where in the cell? what is its function?
in animal cells near nucleus function: MTOC: microtubule -organizing center
26
the centrosomes are made of 2 components? which are composed of?
centrioles 9 microtubules triplets(9+0)
27
after mitosis, what happens to centrioles?
it separates them to each daughter cell
28
what means the arrangement 9+0
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
who is long and short? cilia and flagella?
flagella long cilia short
30
both cilia and flagella are what? and made of what? | and their function?
are appendages in eukaryotic cells made of microtubules function: for locomotion, move around the fluid and feed(cilia only not flagella)
31
both flagella and cilia have a core named....
axoneme
32
the axoneme is made of what type of arrangement and explain it and it is covered by....
9+2 9 outer doublet microtubules 2 inner single microtubules the axonema is covered by the plasma membrane
33
the sliding of microtubules onto each other depends on which motor protein?
dynein
34
during infection, sars-cov 2 causes what?
losses/shortening of cilia(axoneme) in trachea epithelial cells misorientation of the basal body???demande prof
35
if the % of ciliated area decreases, the means clearance of viral particles.........
decreases
36
La position de alpha et beta dans le dimère?
Beta en haut vers le +end et alpha en bas du dimère vers le - end
37
what are microfilaments?composed of what?
thin filament composed of actin proteins acting alone or with myosin to cause cell contraction
38
what is the structure of microfilaments?
double chain of actin subunits(2 intertwined strands of actin)
39
function of microfilaments
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
the sliding of microfilaments(thin) into each other is powered by the
myosin
41
donne l'ordre croissant, de la plus petite longeur vers la plus grande, des intermediate filaments, microtubules, microfilaments
1. plus courte : microfilament 2. intermediate filament 3. microtubules(le plus long)
42
what are intermediate filaments?
Strong and flexible filaments of intermediate size that provide mechanical support of the cell against physical stress(pressure)
43
intermediate filaments are only found in the cells of some
animal, including vertebrates | ex: keratin found in epithelium, scales, hair, nails, feathers, horns, claws, hooves, skin
44
who has a more permanent structure? microtubules, microfilaments or intermediate filaments?
intermediate filaments (not disassembled and reassembled as much as microtubules and microfilaments
45
function of intermediate filaments
can bear tension(like microfilaments) maintain shape of the cell and the nucleus(nuclear lamina) fix the position of organelles
46
intermediate filaments are made of what?
keratin proteins and others proteins
47
plasmodesmata is found
ONLY in plants
48
neighbouring cells of multicellular organisms ..... and .....to one another
adhere communicate
49
in plants, neighbouring cells are connectec by cytoplasmic channels called
plasmodesmata
50
what does plasmodesmata?
it goes through the cell walls, making the membrane continuous between cells letting then many substances to pass through to another cell
51
in animals, there are 3 types of cell junctions
tight junctions desmosomes gap junctions
52
what are tight junctions
plasma membranes of adjecent cell are bound together by proteins
53
function of tight junctions
prevents leakage of fluid through the epithelium layers this is impermeability
54
give where we could find tight junctions?
epithelial cells such as skin cells and enterocytes(epithelial cell of intestines) or endothelial cells such as blood vessels cells
55
what are the components of a tight junctions and they differ in what?
occludin claudin these 2 differ in their transmembrane domain
56
what are desmosomes?
anchors adjacent cells together through transmembrane proteins (that velong to the cadherins family) that are linked to the intermediate filaments
57
function of desmosomes
keep adjacent cells tight together, especially in tissues that can stretch like myocyte(muscle cell)
58
cadherins of desmosomes can attach to what inside the cell?
intermediate filaments
59
who is similar to plasmodesmata(in plants)?
gap junctions(animals)
60
gap junctions are made of what?
6 proteins (connexins) form a channel and allow the communication of adjacent cells
61
function of gap junctions
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
where we could find gap junctions?
heart muscles cells
63
what is a connexon
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