Cell Membranes

Question 1

Function of lipid bilayer

Answer 1

Provides barrier for water-soluble molecules

Question 2

Function of membrane proteins

Answer 2

For carbohydrates to bond to these

Question 3

Integral membrane proteins

Answer 3

Have hydrophobic regions of amino acids that penetrate or entirely cross the phospholipid bilayer

Question 4

Transmembrane proteins

Answer 4

Have specific orientation, showing different ‘faces’ on each side of the membrane

Question 5

Peripheral membrane proteins

Answer 5

Lack hydrophobic regions and are not embedded in the bilayer

Question 6

Anchoring of restricted molecules

Answer 6

Either anchored to cytoskeleton or trapped within lipid rafts

Question 7

Carbohydrate-bound lipid

Answer 7

Glycolipid

Question 8

Carbohydrate-bound protein

Answer 8

Glycoprotein

Question 9

Tight junctions

Answer 9

Link adjacent epithelial cells, restrict migration of membrane proteins and phospholipids, prevent substances from moving through intracellular space

Question 10

Gap junctions

Answer 10

Facilitate communication between cells, made of connexons (specialised protein channels that span plasma membranes and protrude sightly).

Question 11

Desmosomes

Answer 11

Dense plaques attached to both cytoplasmic fibres and to membrane cell adhesion proteins which bind to proteins of an adjacent cell

Question 12

Diffusion

Answer 12

Random movement towards state of equilibrium (slow)

Question 13

Factors that impact diffusion rates

Answer 13

Temperature, size, electrical charge, concentration gradient

Question 14

The more lipid-soluble the molecules…

Answer 14

The faster they diffuse

Question 15

Hypertonic

Answer 15

Dehydrated

Question 16

Isotonic

Answer 16

Average

Question 17

Hypotonic

Answer 17

Over hydrated

Question 18

Three types of protein that use active transport

Answer 18

Uniport, symport, antiport

Question 19

Primary active transport

Answer 19

Only cations such as sodium, potassium, and calcium

Question 20

Secondary active transport

Answer 20

Uses established gradients to move substances (e.g. Symport system in intestinal cells)

Question 21

Types of endocytosis

Answer 21

Phagocytosis, pinocytosis, receptor-mediated endocytosis

Question 22

Pinocytosis

Answer 22

Used to acquire fluids from blood

Question 23

Phagocytosis

Answer 23

Defends body from invasion by foreign cells

Question 24

Receptor-mediated endocytosis

Answer 24

Highly specific pinocytosis

Question 25

Exocytosis

Answer 25

Vesicle membranes fuse with plasma membrane and release vesicle contents into the environment