Unit 1- Membraine Proteins Flashcards
Describe a phospholipid.
Hydrophilic charged head with a hydrophobic tail. Phospholipids are arranged in a bilayer in the membrane.
Describe integral proteins.
Proteins within the membrane which interact with the hydrophobic tails by hydrophobic interactions. (Hydrophobic R groups).
Describe peripheral proteins.
Peripheral proteins are on the surface of the membrane and are bound by ionic and hydrogen bonding.
Describe facilitated diffusion.
The passive transport of substances across the membrane through specific transmembrane (integral) proteins, channel proteins and transporter proteins.
What are the 2 types of channel proteins?
Ligand gated, voltage gated.
Describe a ligand gated channel protein.
When the correct signal molecule binds, the gate opens allowing ions to flow through.
Describe a voltage gated channel protein.
Voltage gated channels are controlled by changes in ion concentration.
Describe a transporter protein.
Transporter proteins bind to the specific substance to be transported then undergo a conformational change to transfer the substance across.
Describe a protein pump.
Transporter proteins that carry out active transport while coupled to an energy source. Against the concentration gradient.
What are ATPases?
Proteins which hydrolyse ATP directly to provide energy for a conformational change.
Describe the process of the sodium potassium pump.
1) Pump has a high affinity for sodium ions inside the cell so they bind.
2) Pump hydrolyses ATP, phosphate attaches to pump (phosphorylation).
3) Phosphorylation causes conformation change.
4) Affinity for sodium now decreases so sodium ions are released outside cell.
5) Pump now has high affinity for potassium ions, so they bind.
6) De phosphorylation causes conformation change.
7) Affinity for potassium decreases so they are released into cell and sodium affinity increases.
What is the exchange of Na and K ions.
3 Na ions out AND 2 K ions into the cell.
[ 3SOUT —> 2KIN ] Going.