Regulation of animal cell shapes - L6

Question 1

What is the function of the cytoskeleton?

Answer 1

*Maintains cells shape
*Protects
*Maintains the position of organelles in the cell
* its dynamic i.e constantly dis and re- assembling to change its shape to need/ to divide
* It’s dynamic but still provides stability

Question 2

3 key components of the cytoskeleton

Answer 2

Microfilaments, microtubules and intermediate filaments

Question 3

Microtubules

Answer 3

*tiny, hollow, cylinder shaped, 25nm, alpha and beta
*cylinder resists compression
* made of tubulin subunits
*can be independent or radiate from a centrosome
* These give a cell its shape

*gives motility
- Flagella - snake like
-Cillia - rowing - if cells are fixed, the cillia just move fluid past them

*Gives motility inside the cell where motor proteins attatched to the vesicle “walk”along the microtubule, allows them to reach specific targets in the cell

Question 4

Microfilaments

Answer 4

*Made of thin threads of actin, that twist to form a rope of actin subunits.
*Play tug of war, it resists tension
*Can run individually or form the 3D cortical network right under the plasma membrane –> if cells gets pulled on it resists tension

Actin and myosin (motor protein) react to support cell movement and muscle contraction

Question 5

Intermediate filaments

Answer 5

• Made of keratin that form bundles and strong cables of fibrous subunits
  *it isnt dynamic and does’t break down and build often hence it is relatively permanent in the body. Sometimes its stays even after cell dies.
• Called lamins in nucleus and neurofilaments in neurons. Keratin in hair under the cuticle, looks rougher if cuticle is damaged

Question 6

3 types of cell junctions

Answer 6

Tight
Desmosome

Question 7

Tight junction

Answer 7

*keeps cells pressed tightly together
*not good at resisting tension
*continuous seal i.e prevents fluids from leaking through, allows some stuff through or not depending on need
*Attatches to the cortical network

Question 8

Desmosome

Answer 8

*Connections between sheets of muscle, torn muscle are torn desmosomes
*Acts as rivets into muscle
*Connects to intermediate filaments
*Anchor junctions and resists tension

Question 9

Gap junctions

Answer 9

*Has a gap through them
*Cytoplasm of one cell conects to cytoplasm of another
*Send info i.e small ions etc v quickly, comms are quick no need for vesicles

Question 10

ECM

Answer 10

where cells aren’t connected to each other, connected by ECM and fibres in ECM. Components of ECM made by cell itself and different cells make different components.

Secretion by constitutive exocytosis

Glycoproteins have little sugar are abundant i.e collagen
Proteoglycan - has lots of sugar, collagen are held in place embedded by these, traps H2O in its branches, helps to resist compression, gives bulk tissue and helps tissues to retain shape

Question 11

Good for skin

Answer 11

Bovine (cow collagen)