Topic 1.3: Membrane Structure

Question 1

What is the structure of a phospholipid?

Answer 1

Consist of a polar head (hydrophilic) composed of a glycerol and a phosphate molecule

Consist of two non-polar tails (hydrophobic) composed of fatty acid (hydrocarbon) chains

Question 2

Is the head of a phospholipid hydrophilic or hydrophobic?

Answer 2

hydrophilic head

Question 3

Is the tail of a phospholipid hydrophilic or hydrophobic?

Answer 3

hydrophobic tail

Question 4

Define hydrophilic

Answer 4

attracted to water

Question 5

Define hydrophobic

Answer 5

repelled by water

Question 6

What is the polar head of a phospholipid composed of?

Answer 6

composed of a glycerol and a phosphate molecule

Question 7

What is the non-polar tail of a phospholipid composed of?

Answer 7

composed of fatty acid (hydrocarbon) chains

Question 8

Define amphipathic

Answer 8

contain both hydrophilic (water-loving) and lipophilic (fat-loving) regions

Question 9

How are phospholipids arranged in membranes?

Answer 9

Phospholipids spontaneously arrange into a bilayer

The hydrophobic tail regions face inwards and are shielded from the surrounding polar fluids, while the two hydrophilic head regions associate with the cytosolic and extracellular fluids respectively

Question 10

How are integral proteins attached to the membrane?

Answer 10

Integral proteins are permanently attached to the membrane and are typically transmembrane (they span across the bilayer)

Question 11

How are peripheral proteins attached to the membrane?

Answer 11

Peripheral proteins are temporarily attached by non-covalent interactions and associate with one surface of the membrane

Question 12

What proteins are permanently attached to the membrane and are typically transmembrane (they span across the bilayer)?

Answer 12

integral proteins

Question 13

What proteins are temporarily attached by non-covalent interactions and associate with one surface of the membrane?

Answer 13

peripheral proteins

Question 14

What are the six functions of membrane proteins?

Answer 14

junctions, enzymes, transport, recognition, anchorage, and transduction

Question 15

Define junction in terms of membrane protein function

Answer 15

Serve to connect and join two cells together

Question 16

Define enzymes in terms of membrane protein function

Answer 16

Fixing to membranes localises metabolic pathways

Question 17

Define transport in terms of membrane protein function

Answer 17

Responsible for facilitated diffusion and active transport

Question 18

Define recognition in terms of membrane protein function

Answer 18

May function as markers for cellular identification

Question 19

Define anchorage in terms of membrane protein function

Answer 19

Attachment points for cytoskeleton and extracellular matrix

Question 20

Define transduction in terms of membrane protein function

Answer 20

Function as receptors for peptide hormones

Question 21

What is cholesterol?

Answer 21

Cholesterol is a component of animal cell membranes, where it functions to maintain integrity and mechanical stability