Plasma membrane Flashcards
Membranes are?
flexible and able to break and fuse easily
What do membranes allow?
cellular compartments to have different conditions
What are membranes mainly made of?
phospholipids
Which head is soluble?
Which head is insoluble?
The hydrophilic heads
the hydrophobic tails
Explain why phospholipids form a bilayer in plasma membranes (4).
Phospholipids have a polar phosphate group which is hydrophilic and will face the aqueous solutions
The fatty acid tails are non-polar and will move away from an aqueous environment
As both tissue fluid and cytoplasm is aqueous
phospholipids form two layers with the hydrophobic tails facing inward
phosphate groups outwards interacting with the aqueous environment
How can polar and non-polar molecules pass through the membrane (2).
Polar molecules require proteins to enable them to pass through the membrane
Non-polar molecules can diffuse directly through the phospholipid bilayer
Explain why the model for membrane structure is known as the fluid mosaic model (3)
The phospholipid molecules can move freely laterally and make the membrane fluid.
The proteins are distributed throughout the membrane unevenly and in a mosaic pattern.
The agreed structure is based upon experimental and chemical evidence and so is classed as a model.
Describe the structure and function of the glycocalyx (3)
Consists of glycoproteins
Which are proteins with added carbohydrate chains
Used for cell recognition/receptors
Other than as carrier proteins state two functions of membrane bound proteins (2).
Receptors
Enzymes
Structural (attached to microtubules)
Why does the membrane lose structure?
high temperature or presence of organic solvents such as alcohol, thereby increasing permeability
what do Glycoproteins form ?
What do they allow?
the glycocalyx
cell recognition
