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 (21 cards)
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?
not the specifics but generally
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
Small, non-polar
What is the role of cholesterol in cell membranes?
Provides stability (bind to phospholipid fatty acid tails, causing them to pack more closely together)
How does cholesterol provide stability?
Binds to fatty acid tails, causing them to pack more closely together
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?
3 key roles
- Cell adhesion - This is the attachment of cells to one another.
- Cell recognition - This allows cells to recognise one another.
- Cell signalling - This is communication between cells.
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 between the cell and its environment, controlling which substances enter and leave the cell.
What is the function of membranes around organelles?
Act as a barrier between the organelle and the cytoplasm, dividing the cell into different compartments (this is sometimes called compartmentalisation).
What does partially permeable mean?
Lets some molecules pass through
