Topic 5- Diffusion and membrane transport Notes PDF

Preview

Summary

Topic 5 - Diffusion and Membrane Transport Notes...

Description

TOPIC 5: Diffusion and Membrane Transport Electrochemical Gradient 

These pumps work against 2 gradients at the same time: o The concentration gradient:  Inside = low concentration of sodium ions (Na+) o The electrochemical gradient (dif. in charge on either side of cells membrane):  Inside = Negative (-)  Outside = Positive (+)



Pump works against both of these gradients: take in 3 (+) charged Na+ and pushes them outside into the Na+ rich environment.



To get the energy to do this, the protein pump breaks up a molecule of ATP. o When ATP (3 P, 1 A) connects to the protein pump an enzyme breaks a covalent bond of one of the phosphate groups, releasing a burst in excited energy. o The bond break releases enough energy to change the shape of the pump so that it opens outward and releases 3 Na+. o This new shape allows it to transport 2 potassium ions (K+) in.



Topic 2c: Carbohydrates (Polysaccharides) Monosaccharides 

1 sugar unit



Typically sweet-tasting



Function as an immediate energy source for cells. o Glucose o Galactose o Fructose

Disaccharides 

2 sugar units



Small enough to be soluble in water



Function as a transport form. o Lactose ( B-D-galactose + B-D-glucose = B glycosidic bond)  B-glycosidic bond: cause the hydroxyl groyp on C-atom 1 of the galactose is in the B-configuration.  Some ppl lack the enzyme needed to hydrolyze this Bglycosidic bond and are considered lactose intolerant (have difficulty metabolizing this disaccharide). o Maltose (a-D-glucose + a-D-glucose = a glycosidic bond)  Both in a-form: glycosidic bond forms between C atom 1 of one glucose and C atom 4 of the other. o Sucrose (a-D-glucose + B-D-fructose = a glycosidic bond)

2



a-Glycosidic Bond: involves a C-atom 1 with its hydroxyl group in the aconfiguration.



B-Glycosidic Bond: the hydroxyl group on C-atom 1 is in the Bconfiguration.



In polysaccharides, the 3-D configuration and the biological role of the polymer depend critically on the nature of the bond between the repeating monosaccharide units.

3...