What are the three components that help to regulate the cell shape?
Extracellular Matrix
Junctions with other cells
Cytoskeleton
What are the three types of components that are part of the cytoskeleton?
Microtubules
Intermediate Filaments
Microfilaments
What is the purpose of the cytoskeleton?
To help maintain cell shape and the position of the organelles.
Microtubules
- Compose of…
- May radiate out…
- Resist…
- Provide…
Composed of tubulin subunits
May radiate out from an organizing centre (centrosome)
Resist compression
Provide cell mobility.
Whole cell mobility - what are the two ways and how do they work?
- Flagella - whole cell mobility, snake-like movement and in the direction of movement.
- Cilia - rowing like motion, perpendicular to the direction of movement. Power then recovery stroke.
- When cells are fixed in pace, the beating of cilia can move fluid past the cells.
What is involved in organelle mobility?
This is where ATP powered motor proteins, and can walk organelles across the microtubules, then to destination.
Microfilament properties?
Double chain of actin subunits
Resists tension
Cortical network under plasma membrane helps maintain cell shape.
Gel-like substance consistency to outer cytoplasm.
What example is microfilaments in the body
Muscle cells, where they are arranged in a parallel with the motor protein myosin.
Intermediate filaments
- Composed of…
- Look like…
- More/Less Dynamic than MT or MC
- Function…
- Various proteins including keratin, vimentins etc.
- Supercoiled ‘cables’
- Less dynamic than MT or MC
- Maintain cell shape and anchor organelles.
What are the major types of cell junctions?
Tight junctions
Desmosomes
Gap junctions
Tight junctions are:
- Are what…
- May what…
- Prevent what…
- Neighbouring cells tightly pressed together
- May form a continuous seal
- Prevent movement of fluid across cell layers
Desmosomes are:
- Are what..
- Attachments of…
- Act like …
- Anchoring junctions
- Attachments between sheets of cells
- Act like rivets (a torn muscle is a desmosome)
Gap junctions are:
- Are what…
- Ions are able to…
- Allows for…
- A point of cytoplasmic contact between cells
- Ions and molecules may pass from cell to cell
- Allow for rapid intercellular communication
What does the ECM consist of?
Glycoproteins (mainly collagen fibres)
Fibroconectins
Proteoglycan Matrix
Properties of Collagen (3)
Great tensile strength
Collagen must be replaced
Over 50% of total body protein is made from collagen
Properties of the Proteoglycan Matrix
They are proteins with extensive sugar additions
Traps water in ECM
Resists compression and retains shape
What provides the communication link between ECM to the cell interior?
Membrane proteins link ECM with cytoskeleton.
What attaches cells to ECM?
Fibroconectins
