Biological Membranes

Question 1

Explain the role of cholesterol snd glycolipids

Answer 1

Cholesterol- connects phospholipids together , reduces fluidity to make the bilayer more stable

Glycolipids- cell signalling and recognition

Question 2

Explain the role of extrinsic + trabsmembrane proteins in membrane

Answer 2

Binding sites
Antigens
Receptors
Involved in cell signalling

Question 3

Explain the role of instrinisic proteibs

Answer 3

Channel proteins (facillitated diffusion£
Carrier proteins (facillitated diffusion/active transport)
Electron carriers

Question 4

Explain the functions of a cell surface membrane

Answer 4

Isolates cyptoplasm from extracellular environnent
Selectively permeable allow transport
Involved in cell signalling and recognition

Question 5

Define osmosis

Answer 5

Water moves from an area eith higher water potential to an area of lower water potential

Question 6

How does osmosis affect animal + plant cells

Answer 6

Osmosis into plant cell = turgid
Osmosis out of plant cell = flaccid

Osmosis into animal cell = lysis
Osmosis out of animal cell = crenation

Question 7

Simple diffusion

Answer 7

Net movement of molecules from an area of high concentration to an area of low concentration
Requires no atp

Question 8

Explain how carrier and channel proteins work

Answer 8

Channel proteins, contain specific hydrophillic channels that bind to specific ions, and opens to release them

Carrier proteins = binds to its contemplentary molecule, this change causes it to release molecule on other side of the membrane, in facillitated diffusion its a passive process, in active transport, it requires ATP

Question 9

Active transport

Answer 9

Specific carrier proteins transports molecules from an area of low concentration to an area of high concentration, requiring atp and it goes against the concentration gradient

Question 10

5 factors rhat affect the rate of diffusion

Answer 10

Temperature
Diffusion distance
Surface area
Size of molecule
Difference in concentration