Membranes Flashcards
What is the structure of a phospholipid?
Choline
Phosphate
Glycerol backbone
Fatty acid chains
What end of the phospholipid is hydrophilic?
Head
What end of the phospholipid is hydrophobic?
Tail
What is an integral protein?
A protein which is permanently attached to the membrane
An intrinsic protein = passes through the whole membrane
What is a peripheral protein?
A protein that can detach from the membrane
Surface bound
An extrinsic protein = does not pass through the whole membrane
What components of the membrane do peripheral proteins interact with?
Embedded proteins
Phospholipid heads
What is passive diffusion?
Movement of molecules across a membrane down a concentration gradient which does not require energy
What molecules pass through membranes by passive diffusion?
Small nonpolar molecules
What is facilitated diffusion?
Movement of molecules across a membrane down a concentration gradient through channels
- Channels may be gated or through intrinsic proteins
What type of molecules pass through membranes by facilitated diffusion?
Hydrophilic molecules and ions
What is active transport?
Movement across a membrane against a concentration gradient which requires energy
What are the different types of active transport?
ATP driven
Coupled transport - a molecule moving by passive or facilitated diffusion ‘pull’ another molecule through
What is it called when molecules are moving in opposite directions across a membrane by coupled transport?
Antiport
What is it called when molecules are moving in the same direction across a membrane by coupled transport?
Symport
What forms of energy are used for active transport?
ATP
GTP = similar to ATP with a different base
Nucleotide-sugars = nucleotide with the last phosphate replaced with a sugar
