Cell membrane transport COMPLETED

Question 1

Compare and contrast PASSIVE TRANSPORT across cell membranes (e.g., energy source, gradients).

Answer 1

Passive Transport:

Energy Source: No external energy required.
Movement Direction: Moves with the concentration gradient (from high to low).
Types of Transport: Includes simple diffusion and facilitated diffusion.
Examples: Oxygen diffuses through the lipid bilayer; glucose enters cells using facilitated diffusion.

Question 2

Compare and contrast ACTIVE TRANSPORT across cell membranes (e.g., energy source, gradients).

Answer 2

Active Transport:

Energy Source: ATP required
Movement Direction: Moves against concentration gradient (from low to high).
Types of Transport: Includes primary (direct) active transport and secondary (indirect) active transport.
Examples: Sodium-potassium pump actively transports sodium and potassium; sodium-glucose symporter (SGLT) indirectly transports glucose.

Question 3

Compare and contrast the membrane transport processes of SIMPLE DIFFUSION.

Answer 3

Simple Diffusion:
Direction: Solutes move high to low concentration.
Energy Source: Passive
Solute Type: Small, uncharged molecules.
Transport Protein: None.
Example: Oxygen and carbon dioxide.

Question 4

Compare and contrast the membrane transport processes of FACILITATED DIFFUSION.

Answer 4

Facilitated Diffusion:
Direction: Solutes move from high to low concentration.
Energy Source: Passive
Solute Type: Larger or charged molecules.
Transport Protein: Yes (channel or carrier proteins).
Example: Glucose via GLUT transporters.

Question 5

Compare and contrast the membrane transport processes of PRIMARY ACTIVE TRANSPORT.

Answer 5

Primary Active Transport:
Direction: Solutes move against concentration gradient (low to high).
Energy Source: ATP hydrolysis.
Solute Type: Often ions (e.g., Na+ and K+).
Transport Protein: Yes (ion pumps).
Example: Sodium-potassium pump (Na+/K+ pump).

Question 6

Compare and contrast the membrane transport processes of SECONDARY ACTIVE TRANSPORT

Answer 6

Secondary Active Transport:
Direction: Solutes move against the concentration gradient indirectly.
Energy Source: Derived from primary active transport or other energy forms.
Solute Type: Varies, often involves co-transport of solutes.
Transport Protein: Yes (symporters or antiporters).
Example: Sodium-glucose symporter (SGLT).

Question 7

Compare and contrast the basic STRUCTUAL differences of transmembrane proteins involved in cell membrane transport.

Answer 7

Structural Differences:

1. Number of Transmembrane Segments:
   Single-Pass Transmembrane Proteins: Have one transmembrane domain.
   Multi-Pass Transmembrane Proteins: Contain multiple transmembrane domains.
2. Overall Protein Structure: Some transmembrane proteins have globular domains; others are more linear.
3. Amino Acid Composition:
   Transmembrane segments contain hydrophobic amino acids.

Question 8

Compare and contrast the basic FUNCTIONAL differences of transmembrane proteins involved in cell membrane transport.

Answer 8

Functional Differences

Transport Proteins:
Transporters (Carriers): Facilitate specific molecule/ion transport.
Ion Channels: Form pores for passive ion diffusion.

Receptors:
Bind ligands, transmitting signals for cellular responses.

Enzymes:
Catalyse chemical reactions within the cell.

Mechanism of Action:
Active Transport: Requires energy for transport.
Passive Transport: Allows passive movement down gradients.

Regulation:
Regulation by Ligands: Many are regulated by ligand binding.
Voltage or Mechanical Regulation: Some are sensitive to membrane voltage or mechanical stress.