Biology 3.3 Flashcards

Phospholipids and Cell Membrane Structure

• Phospholipids are composed of three major parts: a phosphate group, glycerol, and two fatty acid tails.
• The phosphate group and glycerol are charged or polar, making them hydrophilic (water-attracting).
• The fatty acid tails are nonpolar, hydrophobic (water-repelling) components.

Cell Membrane Interaction with Water

• Cell membranes interact with water at two locations: the cytoplasm inside the cell and the extracellular fluid outside the cell.

Bilayer Formation

• Phospholipids arrange into a bilayer because the polar heads face outward towards the watery environments while the nonpolar tails face inward, minimizing contact with water.

Role of Cholesterol

• Cholesterol molecules are embedded within the phospholipid bilayer and serve to strengthen the cell membrane, enhancing its stability and fluidity.

Protein Functions

• Membrane proteins assist in transporting materials across the membrane and are integral to maintaining the cytoskeleton structure.

Carbohydrate Functions

• Carbohydrates attached to proteins and lipids in the membrane play a crucial role in cell recognition and identifying different cell types.

Membrane Fluidity

• The membrane exhibits fluidity, allowing phospholipids to move laterally and slide past one another, contributing to the dynamic nature of the membrane.

Selective Permeability

• Cell membranes possess selective permeability, regulating which substances can enter or exit the cell, a critical function for maintaining homeostasis.