📚 Seth MB


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Cell Membranes: The Fluid Mosaic Model

Last updated Jun 29, 2023 Edit

A cell membrane is roughly 7nm wide

# Biological Membranes

# Phospholipids

A phospholipid has a hydrophilic head and 2 hydrophobic tails.

The hydrophilic heads are in contact with the cytoplasm or the extracellular fluids, and the hydrophilic tails stay away from water in the centre of the membrane.

# Membrane Proteins

# Glycoproteins

# Glycolipid

# Cholesterol

# Channel Proteins

# Carrier Proteins

# More depth on Plasma Membrane Composition

Phospholipids can have slightly different tails. Their tails are made from fatty acids, but not always the same. A straight tail is made of saturated fatty acids and a tail with a kink in it (caused by a C=C double bond) is an unsaturated fatty acid.

The purpose of a kinked tail is increased membrane stability. It separates phospholipids out and prevents them from becoming too tightly packed.

Cholesterol fits in with the phospholipids and helps to regulate the fluidity of the membrane. It does this by increasing fluidity at low temperatures by keeping the phospholipids apart and preventing a cease in motion. At higher temperatures, they have the opposite effect and reduce the fluidity of the membrane by holding the phospholipids in place and stopping them from moving too much.