Flashcards in Cytoskeleton (introduction) Deck (35):
What is the cytoskeleton?
Structural framework of the cytoplasmic matrix in eukaryotic cells
Do prokaryotes have a cytoskeleton?
What are the major roles of the cytoskeleton?
1)Act as a scaffold
2)responsible for the internal positioning of of organelles within the cell
3)required for cellular trafficking
4)force generating elements responsible for movement of the cell
5) sites for anchoring mRNA and facilitating translation
6)role in signal transduction
7)roles are accomplished by various proteins associated with the cytoskeleton
What is its function when it acts as a scaffold?
provides structural support that determines the shape of the cell
What is the cytoskeleton function when it functions in cellular traffic?
1)transports vesicles/ organelles to specific sites in the cell
2)invagination of membrane w/ endocytosis
3)separation of chromosomes during endocytosis
What is the force generating elements responsible for movement of cells from one place to another?
1) extending process of fibroblast
2)cilia and flagella
What is the extending process of fibroblast function in?
crawling on the surface
What is the cytoskeleton role in signal transduction?
deformation of cytoskeletal elements when it comes in contact with another cell or object
What are some roles of accessory protein of the cytoskeleton?
assembly/disassembly of cytoskeletal filaments
What are the role of the motor proteins?
move things along filaments
What does the cytoskeleton consist of?
filamentous protein structures that are held together by noncovalent bonds.
What are cytoskeletal filamentous structures composed of?
multiple protein subunits
What are protofilaments?
linear arrangements of cytoskeletal monomers
What does multiple protofilaments form?
they interact to form the final cytoskeletal structure
What are key points of regarding the structural arrangement of cytoskeletal structures?
1)protein subunits are relatively small
2)multiple protofilaments provides stability to the whole structure
Why are the protein subunits small?
they can move rapidly to region where cytoskeletal elements are growing
What does rapid movement of cytoskeletal subunits allow?
The cell to break down filament at one site and build it back up in the other part of the cell
What does non covalent bonds of cytoskeletal subunits allow for?
rapid growth and breakdown
How does individual protofilament subunits interact to stabilize?
end to end to form protofilaments
side by side to hold protofilaments together
What does the side by side and end to end interaction allow?
Stabilization in the middle of the of the filament while allowing the ends to polymerize/depolymerize easily
What does multiple protofilaments convey?
added strength and resistance to bending
(especially for intermediate filaments)
What are the main types of cytoskeletal filaments?
What are characteristics of all intermediate filaments?
tough rope like fibers
several different proteins that have similar structures
What is the diameter of intermediate filaments?
intermediate between microtubules and actin/microfilaments
What are characteristics of microtubules?
hollow cylindrical structure
make a single type of structure (13 protfilament tube)
What are some structures made up of microtubules?
What family of proteins that microtubules belong?
tubulin protein family
there are 3 different types of tubulin proteins
What is the diameter of microtubules?
25nm in diameter
What are characteristics of microfilaments ?
solid, thinner structures
make single type of structure (a two stranded helical filament)
What are the proteins that microfilaments are composed of?
Globular actin (g-actin)
What is microfilaments also called?
actin filaments (f-actin)
What is the diameter of microfilaments?
Where are intermediate filaments located?
dependent upon specific form/protein that makes up the specific intermediate filament
What does microtubules form?
Tracks through the cell
radiate from out from centrosome near center of cell (not always)