Regulation Of Animal Cell Shape

Question 1

What is the function of the cytoskeleton

Answer 1

MPA
Maintain cell shape
Position organelles within the cell
Allows rapid changes in cell shape

Question 2

What allows rapid change in cell shape

Answer 2

The ability for the cytoskeleton to rapidly disassemble and reassemble

Question 3

What 3 components is the cytoskeleton made of

Answer 3

Microtubules
Microfilaments
Intermediate Filaments

Question 4

What is the structure, and function of Microtubules

Answer 4

Composed of tubulin subunits
They may radiate out from an organising centre (centrosome)
Resist compression thus help maintain cell shape

Question 5

How do Microtubules enable cell mobility

Answer 5

Flagella - snake like motion
Cilia - rowing like motion

Question 6

How do fixed cells move fluid past them

Answer 6

The beating of cilia

Question 7

How are Microtubules involved in organelle mobility

Answer 7

ATP powered motor proteins can walk organelles along microtubules
Allow vesicles or other organelles to be transported to specific targets within the cell

Question 8

What is the structure and function of Microfilaments

Answer 8

Microfilaments are a double chain of actin subunits
They form linear strands, and 3 dimensional networks
Microfilaments resist tension

Question 9

How do Microfilaments maintain cell shape

Answer 9

The cortical network (outermost layer under plasma membrane) helps make this region less fluid and thus maintain cell shape
Resist tension

Question 10

How do Microfilaments allow muscle contraction

Answer 10

Actin myosin interactions allow muscle contraction

Question 11

What is the structure and function of Intermediate Filaments

Answer 11

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

Question 12

How permanent are the structures that intermediate filaments form

Answer 12

Relatively permanent structures

Question 13

What are the 3 major types of cell junctions

Answer 13

Tight Junctions
Desmosomes
Gap junctions

Question 14

What are the characteristics of tight junctions
HMP

Answer 14

Hold neighbouring cells tightly
May form a continuous seal
Prevent movement of fluid between cell layers

Question 15

What are the characteristics of desmosomes
CAA

Answer 15

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

Question 16

What are the characteristics of Gap junctions
PIAT

Answer 16

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

Question 17

Where are cells that do not contact other cells found

Answer 17

In the extracellular matrix

Question 18

What is the extracellular matrix composed of

Answer 18

Material secreted (via constitutive exocytosis) by cells

Question 19

What types of proteins are most common in the ECM, and which is the most abundant of these types

Answer 19

Most ECM proteins are Glycoproteins
The most abundant Glycoprotein is Collagen

Question 20

What types of matrix are collagen fibres embedded in

Answer 20

Proteoglycan complex matrix

Question 21

What are proteoglycans and how do they help retain tissue shape
PTW

Answer 21

Proteins with extensive sugar additions
Trap water within the ECM
Water resists compression and thus helps retain tissue shape

Question 22

What are fibronectins

Answer 22

Glycoproteins that attach cells to the ECM

Question 23

What are integrins

Answer 23

Membrane proteins that connect the ECM to cytoskeleton