Lecture 6: Regulation of animal cell shape Flashcards
Cytoskeleton function:
- maintains cell shape
- can reassemble
- dynamic but still provides stability
Three main components of the cytoskeleton:
Microtubules
Microfilaments
Intermediate filaments
Microtubule composition:
tubular subunits
radiate out from centrosome
Microtubule function:
resist compression
maintain cell shape
Additional functions of microtubules:
cell motility through:
- flagella
- cilia
Organelle motility uses
ATP-powered motor proteins to move along microtubules
Microfilament composition:
double chain of actin subunits, forming:
- liner strands
- 3 dimensional networks (using branching proteins)
Microfilament functions:
resist tension
maintain cell shape
cortisol network makes region less fluid
Additional functions of microfilaments:
myosin, actin interactions allow:
- muscle contraction
- cytoplasmic streaming
- amoeboid movement
Intermediate filament composition:
various proteins super coiled into cables e.g.
- keratins in hair
- lamins in the nucleus
- neurofilaments in neurons
Intermediate filaments functions:
- form relatively permanent structures
- maintain cell shape
- anchor organelles
Three major types of cell junctions:
Tight junctions
Desmosomes
Gap junctions
Tight junctions:
- Hold neighbouring cells together
- may form continuous seal
- prevent movement of fluid
Desmosomes:
- anchoring junction
- provide attachment between sheet of cells
- act like rivets
- connected into the cell by intermediate filaments
Gap junctions:
- point of cytoplasmic contact between two cells
- ions/small molecules can pass from cell to cell
- allows rapid intercellular communication
