u1: chemistry of life

surface tension

water molecules near the surface are more attracted to each other than to surrounding air

result of cohesion

solvent

substance that dissolves a solute

solute

substance that dissolves in solvent

nonpolar

eg. oxygen, carbon dioxide

passes through phospholipid bilayer

polar

eg. water, ethanol

small polar can pass through phospholipid bilayer

exergonic

negative ∆G (LOSE ENERGY)

releases free energy

is catabolic; breaks down

adhesion

attraction for molecules of a different kind

cohesion

attraction for molecules of the same kind

universal solvent

high heat capacity

high heat of vaporization

cohesion and adhesion

polar

importance of water for life

endergonic

positive ∆G (GAIN ENERGY)

requires input of energy

anabolic; forms products

ΔG = ΔH - TΔS

gibbs’ free energy formula

enthalpy (order)

∆H - energy stored in bonds

entropy (disorder)

∆S

positive = more disordered

negative = more ordered

change in free energy

ΔG

organic molecules

molecules with carbon in it

hydrocarbon

molecules with hydrogen and carbon

isomers

same atoms, different arrangement

structural isomer

different covalent arrangement of atoms

geometric isomers

trans (opposite side) cis (some side)

different arrangement around bilayer

enantiomers

3d placement of atoms different

hydrogen bonds

hydrogen attracted to negative charges

weakest bond

dehydration synthesis

condensation reaction releases 1 water molecule

anabolism (requires energy)

glycosidic linkage

hydrolysis

catabolism (releases energy)

adds water molecule to break bond

rings forms

5- or 6- carbon sugars exist as either linear chains or in ring form

prefers ring form (esp aqueous solutions)

disaccharides

2 monosaccharides linked by dehydration synthesis

glycosidic linkage

oligosaccharides

a few monosaccharides together

additional functional groups bonded to proteins and lipids

polysaccharides

long chain of monosaccharides linked by glycosidic linkage

starch (storage polysaccharide)

stores energy in plants

glycogen (storage polysaccharide)

stores energy in animals

cellulose (structural polysaccharide)

structure in cell walls

chitin (structural polysaccharide)

exoskeleton for organisms (eg. fungi, bees)

lipids

made up of nonpolar and hydrophobic hydrocarbons

triglycerides

3 fatty acids + 1 glycerol

forms ester bonds (covalent)

saturated fatty acids

solid at room temp (no kink in chain)

packs tightly to build up plaque

unsaturated fatty acids

kink in cis-fat, can’t pack closely

liquid at room temperature

essential fatty acids

fatty acids needed in humans but not synthesized in the body

phospholipids

2 fatty acid + phosphate group + glycerol backbone

partially negative charge

hydrophilic heads attracted to aqueous solution

hydrophobic fatty acid tails cluster in the middle

waxes

long fatty acid chains esterified to long chain alcohols

hydrophobic, water won’t stick to surface

on feathers of aquatic birds/leaves of certain plants

steroids

closed ring structure (4 linked carbon rings)

hydrophobic & insolube in water

cholesterol

maintains fluidity in the phospholipid bilayer

synthesized in liver

primary structure

order of amino acids in a polypeptide

secondary structure

the way proteins fold, formed by hydrogen bonding

• alpha helix

• beta pleated sheet

tertiary structure

3d structure/properties of side chains

• disulfide bridges

• hydrogen bonding

• van der waals interactions

• ionic interactions

quaternary structure

arrangement of multiple peptide chains

• hydrophobic and ionic interactions

• hydrogen bonds

denaturing

destroying secondary & tertiary structure by disrupting weaker interactions

• high temp

• change in pH

• change in solvent (eg. polar to nonpolar)