Cell Membrane Structure and Function

Overview

• All cells are surrounded by a cell membrane, also known as the plasma membrane.
• The membrane acts as a barrier that regulates the entry and exit of substances in the cell.
• It is described as semi-permeable or selectively permeable.

Composition of the Cell Membrane

Phospholipid Bilayer

• Phospholipids: The primary component of the membrane.
  • Structure: Consist of a hydrophilic (water-loving) phosphate head and two hydrophobic (water-fearing) fatty acid tails.
  • Arrangement: Form a bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward towards water.
  • Function: Primarily responsible for the membrane's selective permeability.

Cholesterol

• Role: Stabilizes the membrane.
• Function: Enhances the membrane's ability to control the passage of substances.

Proteins

• Function: Facilitate transport of materials across the membrane, especially those difficult to pass through the phospholipid bilayer.

Carbohydrates

• Function: Involved in cell identification.
  • Example: Blood type is determined by carbohydrates attached to proteins in the membrane, helping to identify self from non-self.

Importance

• The plasma membrane is a crucial barrier for all life on Earth.

Additional Information

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