Lecture 2

1) Covalent bonds have 80kcal/mole

2) Polar molecules are able to dissolve certain kinds of compounds.

3) Water has energy 5kcal/mole. Thermal energy has 0.6kcal/mole.

4) micell – lipids form in water

5) lipid bilayer – is the way most biological membranes are organized, because biological membranes separate two hydrophilic spaces. In eukaryotic  cells, you want to separate two aqueous layers. When you see a membrane, implicit is the fact that it’s a bilayer.

6) Esterification. Reverse is hydrolysis, reintroduce water.

7) Selective permeability of membranes. Polar molecules cannot go through. Most of our energy is spent in running pumps that keep these concentrations intact inside and outside of the cell.

8) Carbohydrates – one carbon atom roughly per water molecule. Glucose has 6 carbon atoms. Called a hexose. Pentose has 5. Glycerol is also considered a carbohydrate, but its a triose.There are mechanisms to join two glycerol molecules to form a hexose.

9) Hexose isn’t linear. Because of thermodynamic reasons, it likes to cyclise.

10) Stereochemistry refers to the 3d structure of a molecule. Dictated by which atoms are present (tetravalent, trivalent, etc.) as well as thermodynamic considerations. One of the 6 atoms in the cycle is a oxygen, not a carbon, and a CH2OH is relegated to the outside – called extracyclic.

11) What’s the difference between alpha glucose and beta glucose? Whether the hydroxyl is above the plane or below the plane.

12) Glucose and galactose differ in the spatial arrangement of the atoms – particularly the relative positions of the hydroxyl groups. There exist catalysts, called enzymes that can convert one to another.

13) Monosaccharides converted to disaccharides through esterification reaction.

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