Plasma Membrane Flashcards
What does hydrophilic mean?
Loves water/aqueous
What does bilayer mean?
Consisting of two layers
What fatty acid makes up the plasma membrane?
Lipids
What is the role of the plasma membrane?
The plasma membrane (phospholipid bilateral/lipid bilayer/cell membrane) is a structural component of the cell that isolates the cell components (organelles,cytoplasm) from the extra cellular environment.
What is the phospholipid bilayer?
The structure of the plasma membrane.
Name other functions of the plasma membrane?
- To maintain an internal environment
- To control what enters/exits the cell/organelle
- Gives the cell shape
- Contains important components for cell recognition
- Protection
What is the structure of a phospholipid?
- A phosphate group hydrophilic (so it can form hydrogen bonds with water molecules) head
- Two fatty acid(lipid) tails that face into each other, indicating they’re hydrophobic
- Joined by a glycerol molecule
What is the use of a hydrophilic head and hydrophobic tails?
When placed in water, the phospholipid molecules naturally align into a bilayer, allowing the hydrophobic tails to avoid water whilst the hydrophilic heads form hydrogen bonds with water molecules.
The lipid bilayer will form a closed sphere (liposome) to completely exclude water from the hydophobic tail- so the interior is hydrophobic.
Why is the phospholipid bilayer/plasma membrane said to be drawn in a ‘fluid mosaic’ model?
- Individual phospholipid molecules can move within a layer relative to one another - making it fluid
- The varying proteins embedded in the bilayer make it mosaic
What is the name of the carbohydrate layer around the membrane?
Glycocalyx
What does cholesterol do to the membrane?
It sits between the phospholipids to prevent close packing therefore keeping the membrane rigid; more cholesterol means more rigidity. Also makes it less permeable to small molecules.
At cool temperatures, when other membrane components have reduced kinetic energy, cholesterol keeps the membrane fluid and functioning.
What are the function of glycolipids and glycoproteins on the membrane?
Act as markers for cell recognition and hormone receptors. Made of carbohydrate chains protruding from cell surface.
What does bulk transport refer to?
Exocytosis & endocytosis the movement of substances/large molecules
Definition of hydrophobic
Hates/repels water
How does the phospholipid bilayer form in watery areas?
The hydrophilic/polar phosphate heads of the bilayers align themselves so the hydrophobic fatty acid tales are tucked in the middle away from the water.
