Plasma Membrane and Organelles Flashcards
What are the functions of a cell?
- manufacture cellular materials
- Obtain raw materials
- Remove waste
- generate the required energy.
How do we keep a cell inside alive and the outside dead?
To keep these conditions we use a plasma membrane.
- provides special condition within the cell.
- Acts as a semi- permeable barrier.
Do organelles vary in functions?
Yes, not all cells do the same thing.
What are the functions of organelles?
Provide special conditions for specific processes.
Keep incompatible processes apart.
Allow specific substances to be concentrated
Form concentration gradients
Package substances for transport of export.
What are some examples of organelles:
Mitochondrion Endoplasmic reticulum Golgi lysosome (only found in animal cells) Nucleus Chloroplast and central vacuole (only found in plants).
What is the phospholipid bilayer?
Separates the outside of the cell with the inside of the cell we use a phospholipid bilayer.
Hydrophilic head will face the water
Hydrophilic tail will face towards each other (hydrophobic).
Why are cells bounded to the plasma membrane?
This interaction with the environment limits the maximum size of a cell. A small cell has a greater surface to volume ratio than a larger cell (more ability to let substances pass through the membrane as the cell gets bigger, there will be no surface area to allow the movement across the membrane.
Why do phospholipids swap place?
Fluid- unsaturated tails prevent packing (spread out)
Viscous- Saturated tails pack together
A cholesterol stabilises membrane fluidity.
Diffusion movement:
Hydrophobic molecules and (at a slow rate) very small un-charged polar molecules can diffuse through lipid bilayer.
Facilitated Diffusion
Many hydrophilic substances diffuse through membranes with the assistance of transport proteins either channel proteins or carrier proteins.
Active Transport:
Some transport portions acts as pumps, moving substances across a membrane against their concentrations gradients. Energy for this work is usually supplied by ATP.
What happens with defect transport proteins:
Are responsible for many diverse diseases.
Functions of membrane proteins
Signal transduction
Cell recognition
Intercellular joining
Linking cytoskeleton and extracellular fluid.
