7. Plasma membranes and transport

Question 1

Name the structural components of cell membrane

Answer 1

Question 2

What are the types of ECM?

Answer 2

• interstitial ECM (connecting between the cells that are close but not attached - communication space)
• basement membrane (firm, solid structure, stability for cells and attachmement - ex epithelial cells)

Collagen important ECM component

Question 3

What are the functions of glycoproteins and glycolipids on the outside surface of the cell?

Answer 3

• cell to cell recognition (immune system, blood type - sugars on the membrane)

Question 4

Describe the structure of a phospholipid

Answer 4

Question 5

What determines the fluidity of plasma membrane? How was it worked out?

Answer 5

• unsaturated lipids in the phospholipid tails - kinks - prevents packing - spaces created - membrane more fluid -> more viscous - components of the membrane are more free to move around - faster protein interaction
• cholesterol ​- resist temperature effect on the fluidity

Fluidity disovered: mouse and human membranes were marked by different coloured proteins - proteins fused together -> plasma membrane is fluid

Question 6

Explain membrane selectivity

Answer 6

Membrane is selective in molecules which pass through

• very small in size molecules (O2) can pass through no matter hydrophilic / hydrophobic
• small hydrophobic just pass through
• hydrophilic - need specialised channels as inside of membrane is hydrophobic
• big hydrophilic / hydrophobic another mechanism as channels too small - endocytosis / protein pumps

Question 7

What are the types of membrane transport?

Answer 7

Question 8

Explain diffusion

Answer 8

Diffusion - a process during which an equilibrium of concentrations is reached between two environments - not specialised transport (non-specific)

Question 9

Explain osmosis

Answer 9

A special type of diffusion

Aquaporins - channels for water - osmotically regulated cells

Question 10

Explain gated proteins

Answer 10

Question 11

Differentiate uniporter vs symporter vs antiporter membrane transport proteins

Answer 11

Uniporter - transports single species

Symporter - fast transport of two molecules ta the same time in the same direction

Antiporter - changes in conformation, transport slower, two different species - cotransporter

Question 12

What is needed to transport against the concentration gradient?

Answer 12

Energy is needed - ATP

Question 13

What is an example of an active transport?

Answer 13

Question 14

Differentiate between endocytosis and exocytosis

Answer 14