7. The Cytoskeleton Flashcards
what is the cytoskeleton
3D system of fibres running through the cytosol
what is the cytoskeleton important for (3)
cell mobility
cell shape
cell division
describe the structure of microfilaments
- 7nm
- 2 G-actin chains twisted around each other
what is the purpose of microfilaments
structural & locomotor functions
muscle contraction
describe the structure of intermediate filaments
8-10nm in diameter
composed of a diverse group of proteins
what are intermediate filaments involved in
maintaining shape of cell
maintaining position of organelles
describe the structure of microtubules
straight hollow rods 25nm in diameter
20 microns long
constructed of globular proteins called tubules
what is the purpose of microtubules
maintenance of cell shape cell mobility (cilia/ flagella) chromosome movement
describe the different types of actin in microfilaments
G-actin monomers polymerise to form filamentous actin (F- actin) - this is a helical molecule
g actin = monomer
f actin= polymer
what effect foes phallodin have on F-actin
prevents disassembly
what are the two types of microtubules
axonemal
cytoplasmic
describe axonemal microtubules
highly organised & stable
found in cilia and flagella
describe cytoplasmic microtubules
dynamic and loosely organised- found in the cytoplasm
microtubules act as tracks which allow vesicle transportation, what two proteins facilitate this
kinesin and cytoplasmic dynein
how does kinesin move along microtubules
using ATP
from -end to +end
how does dynein move along vesicles
using ATP
from + end to - end
the cancer drug taxol treats cancer how
prevents microtubule disassembly and therefore cell division in cancer cells
describe the structure of cilia and flagella
a core of axonemal microtubules
-9+2 arrangement
9 doublets of microtubules in a ring connected to 2 central microtubules by radial spokes
in cilia and flagella, each doublet is connected to sidearms composed of what?
dynein
true or false:
intermediate filaments are not capable of dynamic movement
true
what is the diameter of intermediate filaments
8-12 nm
