Plasma membrane is semi permeable, only certain molecule can move across it. Certain molecule can move across it.

According to fluid mosaiz model plasma membrane

Composed mainly of phospholipids & protein.

Each phospholipid consists of two parts:

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A polar head- hydrophilic- attracted to water.

Non polar tail-hydrofobic- repel water

Phospholipid bilayer also contain cholesterol

Function to strenten the plasma membrane & more flexible.

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It also contain two type of protein: pore protein: form a channel allows small

Molecules or ions through them.

Carier protein: transport bigger molecules such as glucose, amino acid & vit C.