Lecture Notes: Cell Biology and Membrane Structure

Course Announcements

Quiz grades have been updated; check and understand mistakes.
First exam is next Tuesday in class, same format as quizzes.
- Bring CAS SE ID for identification due to class size (131 students).
- Exam duration is 85 minutes.

Definition: The cell membrane is described as a fluid mosaic.
- Fluidity: Phospholipids can move within their layer, giving the membrane an olive oil-like consistency.
- Mosaic: Composed of various components like gates, channels, pumps, aquaporins, and proteins.

Hydrophilic: Water-loving (interacts well with water).
Hydrophobic: Water-fearing (repels water).
Amphipathic: Molecules with both hydrophilic and hydrophobic parts.
Hydrocarbon: Long chains of hydrogen and carbon, forming phospholipid tails.
Fluidity: Flexibility and movement of phospholipids within their layer.
Transmembrane Protein: Spans the entire membrane, allowing material passage.
Peripheral Membrane Protein: Attached to only one side of the membrane.
Diffusion: Movement of solutes with their concentration gradient.
- Types include simple and facilitated diffusion.

Phospholipids: Fundamental building blocks.
- Head: Phosphate-containing, hydrophilic.
- Tails: Two hydrophobic fatty acid tails.
  - Importance of kinked tails: Prevents tight packing, enhances fluidity.
Cholesterol: Increases membrane fluidity and decreases permeability.
Glycoproteins: Proteins with carbohydrate chains.
- Functions in cell recognition and signaling.
Proteins in the Membrane
- Transmembrane proteins enable movement and signaling.
- Channels form continuous aqueous pores for transport.
- Can increase or decrease in number as needed.

Cell membranes are dynamic and adaptable, integral for cell survival in varying environments.
Course materials and definitions are posted for student review.