The structure and function of membranes Flashcards
What does compartmentalisation mean
The formation of separate membrane-bound areas in a cell
Why is compartmentalisation necessary
It allows for the different and specific environments for the chemical reactions to exist even if they are not compatible with one another
What is the name for the cell surface membrane?
The plasma membrane
What is the main function of the plasma membrane?
It separates the cell from its external environment
What are membranes formed from?
Describe and draw how the phospholipids create a bilayer (and thus the cell wall)
The many phospholipids aramge themselves in a way in which the hydrophilic phosphate heads are both on the inner and outer surface of the membrane, sandwiching the hydrophobic, fatty acid tails in the middle
What type of environment do cells normally live in?
An aqueous environment
What evidence in 1950s arose which supported the theory of the lipid bilayer?
The invention of the electron microscope showed the cell membrane as two black lines.
During 1972 what did the two scientists Singer and Nicolson propose?
The fluid-mosaic model
Why was it called the fluid-mosaic model?
Because the phospholipids are free to move within the layer relative to each other and because the proteins within the layer vary in shape,size and position.
Where are intrinsic proteins located on the membrane?
Through both layers of the membrane
Draw a diagram of an intrinsic protein
What is anther name for an intrinsic protein?
An integral protein
How do intrinsic proteins keep themselves in place?
Hydrophobic R-groups on their external surfaces of the protein interact with the hydrophobic core of the membrane, keeping them in place
What are the three different types of intrinsic proteins?
Channel, carrier proteins, glycoporoteins