Study Notes
The membrane structure is primarily composed of a phospholipid bilayer with embedded proteins, allowing for fluidity and flexibility. Phospholipids — molecules with hydrophilic heads and hydrophobic tails that form a bilayer in water. Example: The bilayer forms because the tails avoid water while the heads are attracted to it. Membrane proteins — diverse proteins that serve various functions such as transport and communication. Example: Integral proteins span the membrane, while peripheral proteins attach temporarily. Cholesterol — a steroid that modulates membrane fluidity and permeability. Example: Cholesterol prevents phospholipid tails from crystallizing, maintaining flexibility.
Exam Tips
Key Definitions to Remember
- Phospholipid
- Amphipathic
- Integral protein
- Peripheral protein
- Cholesterol
Common Confusions
- Confusing the roles of integral and peripheral proteins
- Misunderstanding the fluidity role of cholesterol
Typical Exam Questions
- What is the structure of a phospholipid bilayer? Phospholipids form a bilayer with hydrophilic heads facing outwards and hydrophobic tails facing inwards.
- How do membrane proteins contribute to cell function? They assist in transport, communication, and maintaining cell structure.
- What role does cholesterol play in the cell membrane? Cholesterol modulates fluidity and reduces permeability to certain molecules.
What Examiners Usually Test
- Understanding of the fluid mosaic model
- Differences between types of membrane proteins
- The impact of cholesterol on membrane properties