Lecture 3 Flashcards
What determines membrane permeability of the molecule
Lipid solubility/molecular size
What is diffusion?
movement down a gradient from high to low concentration
What are the different roles of proteins?
Structural, regulatory, receptors, signalling, transport, enzymes, binding protiens, immunoglobins
Describe the hierarchy of cellular transport
Goes through membrane: simple diffusion
Goes through protein: facilitated diffusion, primary/secondary active transport
Goes through vesicle: endo/exo cytosis, phagocytosis
What are the two types of membrane transport proteins and describe the difference
1) Channel –> links intra/extra cellular space, passive transport only (facilitated diffusion), water-filled, high throughput
2) Carrier –> open to one side or other, can be passive or active transport, much slower
How can membrane channel proteins be gated?
Voltage gated, ligand-gated, mechanically-gated
Or, can be passive/leak and open all the time
What is channel protein selectivity determined by?
electrical charge of a.a.s around pore, diameter of the pore
What are the three categories of carrier proteins?
Uniport, Cotransport (symport vs. Antiport)
Describe the difference between primary and secondary active transport, give examples
Primary –> directly uses ATP energy source
ex. Na-K pump –> 3 Na out, 2 K in, Na binds (conformation change, then ATP binds and conformation change, releases Na, K binds to high affinity (conformation change) and release of ATP, causes high affinity for Na again
Secondary –> uses concentration gradient of another molecule that is created by ATP (either symport or antiport)
Ex. Sodium-glucose transporter –> Na moves down concentration gradient, glucose moves against gradient
What are the two types of epithelial cell transport?
Transcellular or paracellular
