Lecture 4 - Plasma membrane and organelles Flashcards
What is a plasma membrane?
A semi-permeable barrier that allows the passage of nutrients, oxygen and waste.
What is a plasma membrane made out of?
Double layer of phospholipids with
various embedded or attached proteins
What are the requirements for a cell?
- Manufacture cellular materials
- Obtain raw materials
- Remove waste
- Generate the required energy
- Control all of the above functions
What are the three factors that effect the static status of the plasma membrane?
Saturation, temperature, cholesterol
How does saturation effect the static status of the plasma membrane?
- Saturated – packed
tightly together, less
fluidity - Unsaturated – tails
prevent tight packing,
more fluidity
How does temperature effect the static status of the plasma membrane?
- High temps more
fluidity - Low temps less fluidity
How does cholestoral effect the static status of the plasma membrane?
Stabilises membrane
fluidity
Which one of the following statements BEST describes the function of organelles.
They:
(A) provide separate compartments with discrete functions.
(B) increase the amount of membrane in a cell.
(C) allow cells to specialise for a specific function.
(D) allow the cell to manufacture cellular materials.
(A) provide separate compartments with discrete functions.
What is signal transduction?
Signal transduction uses membrane
proteins to relay messages from outside the cell to inside the cell
What are membrane proteins involved in? (5)
Signal transduction, cell recognition, intercellular joining, linking cytoskeleton & Extracellular Matrix (ECM), and membrane transport
Hydrophobic molecules normally move across cell membranes by:
(A) Facilitated diffusion.
(B) Active transport.
(C) Simple diffusion.
(D) Endocytosis.
(C) Simple diffusion.
Which two mechanisms are forms of passive transport?
Simple diffusion, facilitated diffusion
What is osmosis?
Movement from a high water
(low solute) concentration to a
low water (high solute)
concentration through facilitated diffusion
What is the main organelle that animal cells have that plant cells don’t?
Lysosome
What are the two main organelles that plant cells have that animal cells don’t?
Central vacuole and chloroplasts
