cytoskeleton Flashcards
protofilament
made of tubulin dimers, is the 13 structures that compose a microtubulin
tubulin
protein that makes up protofilaments and thus microtubules
positive versus negative end of microtubule
positive end; construction occurs more rapidly than destruction.
9+0 arrangement
formation of a microtubule. 9 triplets + lumen in the middle
function of intermediate filaments, and example
cell shape and strength . ex: keraton
nuclear lamins
type of intermediate filament. support the nuclear envelope
definition of interphase cell
cell that isn’t dividing. just sits in the cytoplasm.
centrosome
a.k.a. Cell Center, or MTOC (microtubule organizing center) creates microtubules. Cytoplasmic microtubules emanate out from the centrosome
location microtubules/centrosome during DNA replication
Replicated centrosome now the “poles” in the process of Mitosis
microtubule role in cilia
Ciliated cells: have cilium- move around and beat back and forth- move things past cells. Actual motor inside cell.
microtubule role in flagellum
Flagellated Cell- ex: sperm cells that swim- the long tail of sperm has microtubules, beat, lets it swim along.
centrioles
always occur in a pair, 90 degree angles. Always found in centrosome. Made of microtubule triplets- 3 MT’s glued together. And then another set of 3, and another always 9 triplets in a row, in a circle . 9+0 arrangement
Dynamic instability
microtubules are constantly growing and shrinking. When microtubules assemble tend to bind a GTP, turns into GDP + P, lets them pop off.
how does dynamic instability work?
- tubulin dimers bind to GTP, another energy containing molecule. Tubulin dimers with a bound GTP are much more likely to assemble themselves. Grows until cell cell determines its enough- and then cell hydrolyzes GTP, just like ATP. GTP-> GDP + P(i). those dimers bound to GDP are much more likely to disassemble. Peel away. Whole microtubule begins to shrink, disassemble.
tubulin
protein. dimer composed of alpha and beta protein
how do chemo drugs take advantage of dynamic instability?
Taxol prevents the shrinking/rapid dividing- by stabilizing MT’s.
GTP hydrolysis
cell eating the GTP. the microtubule will GROW when it adds stuff to the GTP cap faster than it hydrolyzes
how do microtubules shrink?
when they are bound to GDP. in this form, protofilaments peel away from microtubule wall
what is the role of centrosomes in cellular division?
- Division: centrosomes line up on POLES, pull chromosomes apart
give an example of cilia in your body. and what type of filament is it?
lungs eliminate debris by using cilia . microtubule
what kind of filament do paramecium use for locomotion?
cilia
- difference between cilia and flagella?
- Cilia are short. Come in large numbers. Made of microtubules.
Flagella are long. Come in 1, or 2 on surface (ex: sperm
internal arrangement structure of cilia/flagella?
9+2 arrangement
axoneme
internal structural component of a cilia/flagella composed of DYNEIN PROTEIN- a molecular motor- that uses the energy of ATP to reach out and grab on to the side of the next doublet and try and push it down past them. Source of the waving, beating motion that u see
dynein
protein that connects the internal microtubules and causes motion in cilia/flagellum
9+2 arrangement
arrangement of microtubules in cilia/flagellum
why do flagellum bend and not slide?
dynein- linking protein- causes the microtubule stalks to bend
how do prokaryotic flagellum work?
- Prokaryotic flagellum: not made from microtubules. Not the same thing!!! Rotates differently- like my arm exercise- by using a rotary motor.
kinesins
motor proteins that only move towards the plus end of microtubles. live in axons, and only walk on MT’s
how does a dinein motor protein ‘walk’ ?
binding and hydrolysis of ATP each cause conformational changes in the motor protein, allowing it to “walk” along the MT track):
microvilli are supported by ___ filaments
actin
myesin
Motor protein- myesin- makes muscle proteins move
give an example of an actin binding protein
myesin
where would you find elastin and collagen? what kind of structures are these?
Cells also produce other fibrous structures in addition to cytoskeleton. The difference is these guys are secreted out. Common ones: elastin, collagen.
Elastin: gives elastic effect to tissues. Collagen: resists stretch.
immunoflurescence: how does it work?
common laboratory technique, which is based on the use of specific antibodies which have been chemically conjugated to fluorescent dyes. These labeled antibodies bind directly or indirectly to cellular antigens
antibody
- protein that has specific binding sites for particular targets “antigens”. Part of immune system.
desmosome
connects 2 cells
what does the cell like to have around it, like a blanket?
extracellular matrix is full of elastin, collagen and other Collective fibers that are held in place by integrin/fibronectin proteins and actin filaments.
globular actin vs fibrous actin?
G actin is a little ball, F actin is a long fiber
which way do kinesin vs dynein move?
- Dynein- works towards minus end
- Kinesin- works toward + end
