Cell Biology 2

Question 1

List the components of cell membranes

Answer 1

1. Phospholipids- phosphoglycerides
2. Cholesterol- sphingolipids
3. Proteins
4. Carbohydrate groups

Question 2

What is the role of cholesterol in the cell membrane?

Answer 2

Fluidity buffer
Enhances permeability- barrier properties
Makes the bilayer less deformable
Tightens the package of lipids
Does not influence the fluidity of the lipid layer

Question 3

What are the factors affecting membrane fluidity?

Answer 3

Temperature
Cholesterol
Fatty acids- saturated vs unsaturated

Question 4

What are the cell membrane functions?

Answer 4

1. Compartmentalisation
2. scaffold for biochemical activities
3. platform to exchange contents with the environment

Question 5

What is the function of integral or intrinsic proteins?

Answer 5

Unique orientation
Different function of its cytosolic and non-cytosolic domains- acts in the both sides of the bilayer
- Signalling and transport from extracellular into intracellular
- Single-pass or multi-pass
- Either alpha helix or beta sheets
- Most are glycosylated on extracellular space
- Reducing environment in the cytosol leads to reduce sulfhydryl groups

Question 6

what do peripheral or extrinsic proteins do?

Answer 6

Attach to one side of the membrane

Question 7

What is the function of glyco-proteins?

Answer 7

Glycolipids are on the extracellular surface of the cell

Question 8

What are the functions of glycolipids?

Answer 8

1. Crucial for cell recognition
2. Interacts with other cells and extracellular matrix
3. Protect against the harsh conditions

Question 9

What is cystic fibrosis?

Answer 9

A genetic disorder affecting mostly the lungs and the pancreas, liver, kidneys and intestine

Question 10

What are long-term issues?

Answer 10

Difficulty breathing and coughing up mucus due to frequent lung infections

Question 11

How is the disease diagnosed?

Answer 11

A sweat test and genetic testing

Question 12

What is cell homeostasis?

Answer 12

Maintenance of a stable, relatively constant internal environment eg. pH, temperature, concentration of salts etc.

Question 13

What is passive transport?

Answer 13

Small molecules
Goes from higher concentration to lower concentration
Does not need energy
simple diffusion vs. facilitated diffusion

Question 14

What is active transport?

Answer 14

Goes against the concentration gradient
Needs energy
Small molecules

Question 15

What is transporter and active membrane transport?

Answer 15

Coupled transporter
ATP-driven pump
light-driven pump

Question 16

Coupled transport- what is uniport, symport and antiport?

Answer 16

Uniport- goes one direction only
Symport- transports 2 molecules simultaneously in the same direction
Antiport- transports 2 molecules simultaneously in the opposite direction
Symport + antiport = coupled transport

Question 17

What is exocytosis?

Answer 17

Secreting and excretion of substances from the cell
Constitutive secretory pathway
Lysosomal secretory pathway
Regulated secretory pathway

Question 18

What is endocytosis?

Answer 18

Engulfing of extracellular substances and bring them into the cytoplasm in membrane-limited vesicles- cell-eating, cell-drinking, triggered by ligand signals