Cellular Processes [Transport - Membranes] Flashcards
Ion channels - passive or active, description, speed
Water filled pores, ions & small molecules, no binding, amino acids lining the pore determine selectivity of ions (specific). Harness the energy stored in gradients. Can be gated.
Name the stimuli that can control channel opening and closing in ion channels
Voltage, ligand binding, cell volume, pH, phosphorylation.
What does the diffusion of ions across ion channels generate?
Current
Can be measure by patch clamp technique
Features of carrier proteins
Passive or active. Conformational change. Slower. Proteins are like enzymes - mediate not catalyse.
What 4 things do membrane proteins and enzymes share?
Specificity, inhibition, competition, saturation.
Facilitated diffusion - type of transport, details, name of Eg.
Carrier. Passive. Down conc gradient. Protein changes shape. Example is glucose coming in and being converted to glucose-6-phosphate.
Active transport - type of transport, description
Utilise metabolic energy. Carrier. Active. Against gradient. 2 types - primary which energy is directly derived from ATP hydrolysis. 2ndary where energy released by a substance diffusing down its conc gradient is used to transport another substance against.
What is the sodium potassium pump good for?
Maintains membrane potential. Contraction of muscle Maintains cell volume. Uptake of nutrients via secondary transport. Maintains pH by secondary transport.
What is the pump leak hypothesis?
Primary. The sodium potassium pump (active transport) works continuously.
Secondary active transport
Uses energy stored in ion gradient created by primary transport. Eg. Na+ anti porter and Na+ symporters are powered by Na+ gradient established by Na/K pump.
Na+ anti porter / exchanger
Na+ in, Ca2+ or H+ out.
Na+ symporters/ cotransporters
Glucose or amino acids in with Na+
