Regulation Of Animal Cell Shape Flashcards
What is the function of the cytoskeleton
MPA
Maintain cell shape
Position organelles within the cell
Allows rapid changes in cell shape
What allows rapid change in cell shape
The ability for the cytoskeleton to rapidly disassemble and reassemble
What 3 components is the cytoskeleton made of
Microtubules
Microfilaments
Intermediate Filaments
What is the structure, and function of Microtubules
Composed of tubulin subunits
They may radiate out from an organising centre (centrosome)
Resist compression thus help maintain cell shape
How do Microtubules enable cell mobility
Flagella - snake like motion
Cilia - rowing like motion
How do fixed cells move fluid past them
The beating of cilia
How are Microtubules involved in organelle mobility
ATP powered motor proteins can walk organelles along microtubules
Allow vesicles or other organelles to be transported to specific targets within the cell
What is the structure and function of Microfilaments
Microfilaments are a double chain of actin subunits
They form linear strands, and 3 dimensional networks
Microfilaments resist tension
How do Microfilaments maintain cell shape
The cortical network (outermost layer under plasma membrane) helps make this region less fluid and thus maintain cell shape
Resist tension
How do Microfilaments allow muscle contraction
Actin myosin interactions allow muscle contraction
What is the structure and function of Intermediate Filaments
Various proteins supercooled into “cables”
They help maintain cell shape, and anchor organelles
Also remain after cell death, as hair or outer layer of skin
How permanent are the structures that intermediate filaments form
Relatively permanent structures
What are the 3 major types of cell junctions
Tight Junctions
Desmosomes
Gap junctions
What are the characteristics of tight junctions
HMP
Hold neighbouring cells tightly
May form a continuous seal
Prevent movement of fluid between cell layers
What are the characteristics of desmosomes
CAA
CAA
Connected into the cell by intermediate filaments
Anchoring junction
Act like rivets/Velcro to attach sheets of cells and prevent cells being pulled apart
What are the characteristics of Gap junctions
PIAT
PIAT
Point of cytoplasmic contact between two cells
Ions and small molecules can pass from cell to cell
Allows rapid cell to cell (intercellular) communication
Tunnel/passage between cells
Where are cells that do not contact other cells found
In the extracellular matrix
What is the extracellular matrix composed of
Material secreted (via constitutive exocytosis) by cells
What types of proteins are most common in the ECM, and which is the most abundant of these types
Most ECM proteins are Glycoproteins
The most abundant Glycoprotein is Collagen
What types of matrix are collagen fibres embedded in
Proteoglycan complex matrix
What are proteoglycans and how do they help retain tissue shape
PTW
Proteins with extensive sugar additions
Trap water within the ECM
Water resists compression and thus helps retain tissue shape
What are fibronectins
Glycoproteins that attach cells to the ECM
What are integrins
Membrane proteins that connect the ECM to cytoskeleton
