Question 1

What do proteins do in the cell membrane?

Accepted Answer

provide structural support act as carrier transporting water-soluble substances function as enzymes form ion channels for sodium, potassium etc. act as energy transducers form recognition sites by identifying cells help cells adhere together act as receptors (e.g. for hormones)

Question 2

What do phospholipids do in the cell membrane?

Accepted Answer

allow lipid-soluble substances to enter and leave the cell prevent water-soluble substances entering and leaving the cell give the membrane fluidity

Question 3

What does cholesterol do in the cell membrane?

Accepted Answer

reduces lateral movement of phospholipids makes membrane less fluid at high temperatures prevents leakage of water and dissolved ions from the cell regulates membrane fluidity

Question 4

What do glycolipids do in the cell membrane?

Accepted Answer

act as recognition sites (e.g. ABO blood system) help maintain stability of the membrane help cells attach to one another and so form tissues cell signalling

Question 5

What do glycoproteins do in the cell membrane:

Accepted Answer

acts as recognition sites for hormones and neurotransmitters help cells attach to one another and so form tissues act as antigens allow mint cells to recognise one another (e.g. lymphocytes can recognise an organism’s own cells) cell signalling

Question 6

Describe a channel protein

Accepted Answer

protein with a specific shape that complements the shape of a substance to be transported across the membrane used in facilitated diffusion

Question 7

Describe a carrier protein

Accepted Answer

protein with specific shape that complements the shape of a substance to be transported across a membrane used in active transport and facilitated diffusion

Question 8

Describe cell signalling

Accepted Answer

• receptors on cells bind to hormones, drugs and other cells, leading to a series of reactions within the cell

Question 9

Describe osmosis

Accepted Answer

water molecules are small enough to pass between phospholipid molecules down a water potential gradient until a dynamic equilibrium is reached

Question 10

Describe the relationship between temperature and permeability

Accepted Answer

high temperature boosts kinetic energy of the component molecules of the membrane and the transported substance, making the membrane more permeable very high temperatures will denature the protein molecules, changing their shape and making the membrane more permeable, eventually the membrane will be destroyed

Question 11

Describe facilitated diffusion

Accepted Answer

large, water-soluble substances cannot pass between lipid molecules and so are carried through the membrane by carrier proteins down a concentration gradient by facilitated diffusion polar, water-soluble substances that cannot pass through the membrane between lipid molecules can be transported via specific channel proteins down a concentration gradient

Question 12

Describe diffusion

Accepted Answer

Small, lipid-soluble substances can pass through the lipid bilayer between the phospholipid molecules, down a concentration gradient

Question 13

Describe active transport

Accepted Answer

Water-soluble substances that must be moved against a concentration gradient require a carrier protein and ATP

Question 14

Describe the glycocalyx

Accepted Answer

the layer of carbohydrates on the outside of the bilayer glycolipids and glycoproteins thickens membrane to 7.5nm

Question 15

Why do phospholipids work well in a membrane?

Accepted Answer

lipids are insoluble in water break up FWPs and watery cytoplasm hydrophilic heads give stability

Cell Membrane Flashcards

(25 cards)