1.3 Membrane Proteins

Question 1

Name the chemical components of a cell membrane

Answer 1

Phospholipid
Intrinsic proteins/transmembrane proteins
Peripheral proteins

Question 2

Explain how different proteins bind to membranes of cells

Answer 2

Transmembrane bound by hydrophobic interactions
Hydrophilic bound on surfaces
Peripheral bound to transmembrane proteins/phospholipid

Question 3

Describe the roles of membrane proteins in facilitated diffusion

Answer 3

Act as channels and transporters

Question 4

Explain the difference between a ligand-gated channel and a voltage-gated channel in a cell membrane

Answer 4

Ligand gated channels have a receptor, specific to a ligand and open when ligand bound.
Voltage gated channels open or close in response to changes in membrane potential.

Question 5

Describe how an ATPase transporter protein works

Answer 5

ATP dephosphorylated by transporter protein
Energy released
To move substances against their concentration gradient

Question 6

Describe how the sodium-potassium pump creates an ion concentration gradient across a cell membrane.

Answer 6

Binds three sodium ions from inside cel
Phosphorylated by ATP and changes conformation
Releases sodium outside and binds two potassium ions from outside
Dephosphorylated and changes conformation
Releases potassium on inside

Question 7

Explain how the glucose symport allows the movement of glucose molecules against their concentration gradient.

Answer 7

Sodium moves through symport down its concentration gradient.
Energy released and used to move glucose in the same direction (even against its concentration gradient)

Question 8

Give examples of a substances that can pass through the phospholipid layer of a cell membrane

Answer 8

Oxygen
Carbon dioxide
Hydrophobic signal molecule

Question 9

Are heads or tails of phospholipids hydrophobic?

Answer 9

They have hydrophobic heads