2.2 Surface Area and Plasma Membrane Flashcards
Surface Area VS Volume
The surface area to volume ratio determines the efficiency of the cell in performing cell transport activities
Small Cells
Higher surface area = easier exchange of materials
Bigger surface-to-volume ratio
Bigger Cells
Surface to Volume ratio decreases = smaller surface area = other ways to manage heat exchange
Prokaryotic cells size
They are smaller than Eukaryotes because they rely on diffusion to bring materials in and out
Diffusion
Moving materials across membranes from high to low concentration
Cell Membranes
-Made of Phospholipid bilayer
- Heads = hydrophilic (inside and outside of cell)
- Tailes = Hydrophobic = interior of membrane)
- Known as Fluid Mosaic model = flexible and have many parts
Cholesterol in Cell Membrane
Provided Fluidity and increased stability
High temp = decreases fluidity, making it more rigid
Low Temp = Increases fluidity making it more flexible
Transfer Proteins
Move ions across membrane
Receptor proteins
Allow the cell to receive signals from enviroment
Integral Membrane Proteins
cannot separate from membrane
Peripheral Membrane Proteins
temporarily associated with membrane
Transmembrane proteins
Span the lipid bilayer
Functions of Proteins in Membrane
-Transport
- Enzymatic activity
- Signal Transduction
- Cell-Cell recognition
- Intercellular joining (help cells stick together and form connections)
- Connect the cytoskeleton (inside) to ECM (outside) to keep the cell shape
HIV infection and cell surface proteins
HIV needs to bind to two cell-surface proteins, CD4 and CCR5, to infect immune cells. People without CCR5 are resistant to HIV because the virus can’t enter their cells. Drugs are being developed to block or mask CCR5, preventing infection.
