chapter 2 Flashcards
cytoskeleton is made of 3 components within the cytoplasm:
microtubules
microfilaments
intermediate filaments
cytoskeleton participates in:
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
what is responsible for the maintenance and modifications of the animal cell’s shape and why?
it is the cytoskeleton
because the animal cells lack cell walls
what are pseudopodia?
these are temporary cytoplasmic projections visible in amoeboid movements
how plants can maintain their rigid shape?
maintained by the cell wall !
what are microtubules?
thick hollow(empty) rod(barre en francais) composed of tubulin proteins
tubuline is what type of structure?(trimer or dimer)
and made of what types of tubuline?
dimer
alpha-tubuline
beta-tubuline
a microtubule can grow and shrink in lingth from ….which end? what is the name of this process?
from the + end
polymerisation
the - end of the microtubule is attached to the……
centrosome
the + and - ends means that they are charged?
non
the main functions of the microtubules:
maintenance of cell shape (compression-resisting girders(poutres)
cell motility( for cilia or flagella)
chromosome movements in cell division
organelle movements
which tubulin is on which side of the end?
tubuline alpha on the - end
tubuline beta on the + end
true or false
both beta and alpha tubuline cand bind GTP?
yes
what happens to the GTP linked to both of the tubulins?
the GTP linked to alpha tubuline stays in form of ATP
the GTP linked to beta tubuline can be hydrolyzed en GDP
how the tubulins are added to each other?
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
how the depolymerisation is made?
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
the rate of GTP hydrolysis on which depend the polymerisation and depolymerization depends on….. and why?
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
the microtubules are able to move what kind of structures inside the cytosol?
organelles
vesicles
enzymes
mouvments of the structures in the cytosol are caused by what? what types of energy?
motor proteins powered by ATP
it converts chemical energy to mechanical energy
give examples of motor proteins
kinesin
dynein
at which end it moves the cargo the kinesin?
towards the + end of the microtubules
towards which end it moves the cargo the dynein?
towards the - end of the microtubules
is it possible for a single vesicle to have both proteins(kinesine and dynein) at the same time? but…
yes
but only one will attach to the microtubule depending towards wich end the vesicle has to go
what do microtubules during cell division? and they radiate from where?
they are involved in the separation of chromosomes during mitosis.
from the centrosome
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