Lecture 4 - Plasma Membrane and Organelles Flashcards
What is the tree of life?
A tree that shows how everything is connected
What must a cell do?
- manufacture cellular materials
- obtain raw materials
- remove waste
- generate the required energy
- control all the above
What are organelles and what do they do?
Organelles are seperate compartments in the cell. Organelles provide special conditions for the different processes in the cell and keep incompatible processes apart. It also allows certain substance to be concentrated and packages substances for transport and export.
Why is it important to seperate internal and external environments?
So the two different environments don’t leech into one another
What does the plasma membrane do?
The plasma membrane acts as a boundary for the cell and provides special conditions within the cell
How many membranes does mitochondria have?
2
What organelles are found in both plant and animal cells?
Endoplasmic reticulum (ER)
Mitochondrion
Golgi apparatus
Nucleus
What are organelles unique to plants?
Central vacuole
Chloroplast
What organelle is unique to animal cell?
Lysosome
Why is the cells maximum size limited?
Due to the plasma membrane
What is the membrane made of?
A very thin continuous phospholipid bilayer
Why does the membrane have to have some fluidity to it?
So we can change things as is needed for the cell
What makes a membrane more fluid or viscous?
It depends on how tightly the phospholipids are packed together
Describe unsaturated vs saturated hydrocarbon tails
Unsaturated tails prevent packing -Fluid
Saturated tails pack together - viscous
What is a saturated and unsaturated hydrocarbon?
Saturated: only single carbon bonds
Unsaturated: contains double or triple carbon bonds
What is the role of cholesterol in animal cells?
To sit and fill in the spaces between unsaturated carbon tails. This helps stabilise membrane fluidity and strengthen membrane.
What are the different ways substance moves across membrane?
Diffusion Facilitated diffusion Osmosis Active transport Co-transport
What is passive diffusion?
Transport with no energy required
What is active diffusion?
Transport with energy used
What are forms of passive transport?
Diffusion
Facilitated diffusion
Osmosis
What are forms of active transport?
Active transport
Co-transport
Describe diffusion
Small hydrophobic molecules that can travel down their concentration gradient through the membrane without energy
(Steroid hormones and gasses)
Describe facilitated diffusion
The use of membrane proteins called channels and carriers to allow movement of bigger molecules and hydrophilic molecules through the membrane down their concentration gradients without energy.
Describe osmosis
A type of facilitated diffusion but for the movement of water through aquaporins in the cell membrane.
