cytoskelteon part one

Question 1

Microtubules

Answer 1

Subunits: two protein dimers (alpha-tubulin and beta-tubulin)
Arranged: dimers stack to make a filament. Need 13 to make microtubules
Size: 25nm
Polarity: Plus and minus end. Plus end builds(beta). Minus end at bottom (alpha)

Question 2

Microfilaments

Answer 2

Subunit: made of actin monomers (globular proteins)
Arranged: a twisted coil
Size: 7nm
Polarity: growth at plus and disassembly at minus

Question 3

intermediate filaments

Answer 3

fibrous protein (keratin and collagen) into cabels
8-12 nm
Individual protein is long and linear. alpha helix
polarity at single and dimer of filament
2 paris of to is when its not polar

Question 4

Within animal cells, what is the major site of nucleation for Microtubules

Answer 4

Y-tubulin ring complex

Question 5

What special Tubulin Monomer is found here and how does that help Microtubules assemble?

Answer 5

Centrosome. Gives alpha tubulin a place to bind

Question 6

What is the main driver for either assembly or disassembly of Microtubules? What is the basic mechanism for that?

Answer 6

GTP- assembly, ring of tubulin dimers can attach
ADP- disassembly . limits growth and disassembly of fiber

Question 7

What are common drugs that affect Microtubule stability and what are their actions?

Answer 7

Taxol
Colchicine
Vinblastine

Question 8

Actin Filaments:
contrast to Microtubules, what nucleotide drives Actin assembly or disassembly?

Answer 8

ATP

Question 9

What are common roles for Actin Filaments in a cell?

Answer 9

Muscle fibers with myosin
Contravtile ring to separate daughter cells
Forms micrivilli

Question 10

How do actin filaments allow an amoeba to chase after food?

Answer 10

Food sensing activates receptors to to grow in actin filaments and is oriented in the same leading direction forming protruding feet. At back end, actin and myosin work together to pull cell along. Actin mnomers at back end diffuse to front rend for reuse.

Question 11

What role is proposed for the nuclear lamina fibers? what is it made of

Answer 11

Maintence of cell shape.cross linked filaments to form a mesh. made up of intermediate

Question 12

there a polarity to an Intermediate Fiber

Answer 12

There is a polar when the filament
There is polarity. C terminus and N terminis with two pairs of dimers
Next pair will align on the opposite sign to form a nonpolar sing
Finished filament is 8 tertrameres twisted together.

Question 13

general, where in cells do we find a lot of Intermediate Filaments?
What roles do they play?

Answer 13

very long and are under stress. prevents from being broken apart
Epithelial cells:
Neural cells:
Muscles/tissue;