4.1 - Structure of the Cell Membrane Flashcards
The role of cell membranes in living organisms The fluid-mosaic model of cell membranes The structure and function of cell membrane components
What is the fluid-mosaic model?
Model describing cell membrane structure (phospholipid bilayer)
What does “fluid” mean in the fluid-mosaic model?
Phospholipids are constantly moving
What does “mosaic” mean in the fluid-mosaic model?
Proteins of different sizes and shapes are embedded
What are the key components of cell membranes?
5 key componenets
- Phospholipid bilayer - This is made up of phospholipids with hydrophilic heads and hydrophobic tails.
- Cholesterol - This adds stability.
- Proteins - These may be intrinsic and extrinsic proteins.
- Glycoproteins - These are proteins attached to a carbohydrate.
- Glycolipids - These are lipids attached to a carbohydrate.
What are phospholipids made of?
Hydrophilic heads and hydrophobic tails
How do phospholipids arrange themselves in a bilayer?
Hydrophilic heads face out
What type of substances can pass through the phospholipid bilayer?
Lipid-soluble substances
What is the role of cholesterol in cell membranes?
Provides stability
How does cholesterol provide stability?
Binds to fatty acid tails
What are the two categories of proteins in cell membranes?
Intrinsic and extrinsic
What are intrinsic proteins?
Proteins embedded through both sides of the bilayer
What is the function of intrinsic proteins?
Transport large molecules and ions
What are extrinsic proteins?
Proteins present on only one side of the bilayer
What is the function of extrinsic proteins?
Provide support or involved in cell signalling
What are glycoproteins?
Intrinsic proteins attached to carbohydrates
What are glycolipids?
Lipids attached to carbohydrates
What are the functions of glycoproteins and glycolipids?
Cell adhesion
What are the two main types of cell membranes?
Cell-surface membranes and membranes around organelles
What is the function of cell-surface membranes?
Act as a barrier
What is the function of membranes around organelles?
Act as a barrier
What does partially permeable mean?
Lets some molecules pass through
