Biologically Important Molecules – II !

Biologically Important Molecules

I.WaterII.Carbohydrates

II. CarbohydratesA. Structure

1. monomer = monosaccharidetypically 3-6 carbons, and CnH2nOn formula

II. CarbohydratesA. Structure

1. monomer = monosaccharidetypically 3-6 carbons, and CnH2nOn formulahave carbonyl and hydroxyl groups

II. CarbohydratesA. Structure

1. monomer = monosaccharidetypically 3-6 carbons, and CnH2nOn formulahave carbonyl and hydroxyl groupscarbonyl is either ketone or aldehyde

II. CarbohydratesA. Structure

1. monomer = monosaccharidetypically 3-6 carbons, and CnH2nOn formulahave carbonyl and hydroxyl groupscarbonyl is either ketone or aldehydein aqueous solutions, they form rings

II. CarbohydratesA. Structure

1. monomer = monosaccharidetypically 3-6 carbons, and CnH2nOn formulahave carbonyl and hydroxyl groupscarbonyl is either ketone or aldehydein aqueous solutions, they form ringsexamples:

II. CarbohydratesA. Structure

1. monomer = monosaccharide2. polymerization:

dehydration synthesis reaction

II. CarbohydratesA. Structure

1. monomer = monosaccharide2. polymerization3. Polymers = polysaccharides

Disaccharides

Polysaccharides

Polysaccharides

Polysaccharides

The ‘cross-linkages’ in cellulose are not digestible by starch-digesting enzymes, so animals cannot eat wood unless they have bacterial endosymbionts. Decomposing fungi and bacteria also have these enzymes, and can access the huge amount of energy in cellulose.

Polysaccharides

H-bonds link cellulose molecules together

Polysaccharides

glucosamine

II. CarbohydratesA. StructureB. Function

- energy storage (short and long) - structural (cellulose and chitin)

CO2

H2O

Glucose, Cellulose,Starch

Biologically Important Molecules

I.WaterII.CarbohydratesIII.Lipids

III. Lipids - not true polymers or macromolecules; an assortment

of hydrophobic, hydrocarbon molecules classes as fats, phospholipids, waxes, or steroids.

III. LipidsA. Fats - structure

III. LipidsA. Fats - structure

glycerol (alcohol) with three fatty acids

(or triglyceride)

III. LipidsA. Fats - structure

-saturated fats (no double bonds)

Straight chains pack tightly; solid at room temperature like butter and lard.

Implicated in plaque build-up in blood vessels (atherosclertosis)

Animal fats (not fish oils)

III. LipidsA. Fats - structure

-unsaturated fats (no double bonds)

Plant and fish oils

Kinked; don’t pack – liquid at room temperature.

“Hydrogenation” can make them saturated and solid, but the process also produces trans-fats (trans conformation around double bond) which may contribute MORE to atherosclerosis than saturated fats)

III. LipidsA. Fats - structure - functions

- long term energy storage (dense) not vital in immobile organisms (mature

plants), so it is metabolically easier to store energy as starch. But in seeds and animals (mobile), there is selective value to packing energy efficiently.In animals, fat is stored in adipose cells

III. LipidsA. Fats - structure - functions

- long term energy storage (dense) - insulation (subcutaneous fat) - cushioning

III. LipidsA. FatsB. Phospholipids

- structure

Glycerol 2 fatty acids phosphate group (and choline)

Hydrophilic and hydrophobic regions

III. LipidsA. FatsB. Phospholipids

- functionselective membranes

In water, they spontaneously assemble into micelles or bilayered liposomes.

III. LipidsA. FatsB. PhospholipidsC. Waxes

- structureAn alcohol and fatty acid

Wax Alcohol Fatty Acid

CarnubaCH3(CH2)28CH2-OH CH3(CH2)24COOH

BeeswaxCH3(CH2)28CH2-OH CH3(CH2)14COOH

SpermaceticCH3(CH2)14CH2-OH CH3(CH2)14COOH

III. LipidsA. FatsB. PhospholipidsC. Waxes

- structure - function

Retard the flow of water (plant waxes)Structural (beeswax)Signals – waxes on the exoskeleton can signal an insect’s

sexual receptivity.

III. LipidsA. FatsB. PhospholipidsC. WaxesD. Steroids

- structuretypically a four-ring structure with side groupscholesterol and its hormone derivatives

Cholesterol

Biologically Important Molecules

I.WaterII.CarbohydratesIII.LipidsIV.Proteins

IV. ProteinsA. structure

- monomer: amino acids

IV. ProteinsA. structure

- monomer: amino acidsCarboxyl group

Amine group

IV. ProteinsA. structure

- monomer:

amino acids

20 AA’s found in proteins, with different chemical properties. Of note is cysteine, which can form covalent bonds to other cysteines through a disulfide linkage.

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration

synthesis

The bond that is formed is called a peptide bond

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration

synthesis- polymer: polypeptide

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration

synthesis- polymer: polypeptideMay be 1000’s of aa’s longNot necessarily functional (“proteins” are functional polypeptides)Sequence determines the function

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration

synthesis- polymer: polypeptide- protein has 4 levels of structure

1o (primary) = AA sequence

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration synthesis- polymer: polypeptide- protein has 4 levels of structure

1o (primary) = AA sequence2o (secondary) = pleated sheet or

helix

The result of H-bonds between neighboring AA’s… not involving the side chains.

Some proteins are functional as helices - collagen

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration synthesis- polymer: polypeptide- protein has 4 levels of structure

1o (primary) = AA sequence2o (secondary) = pleated sheet or

helix3o (tertiary) = folded into a glob

The three dimensional structure of the protein is stabilized by all types of bonds between the side chains… ionic between charged AA’s, Hydrogen bonds between polar AA’s, van der Waals forces, and even covalent bonds between sulfurs.

IV. ProteinsA. structure

- monomer: amino acids- polymerization: dehydration synthesis- polymer: polypeptide- protein has 4 levels of structure

1o (primary) = AA sequence2o (secondary) = pleated sheet or

helix3o (tertiary) = folded into a glob4o (quaternary) = >1 polypeptide

Actin filament in muscle is a sequence of globular actin proteins…

http://3dotstudio.com/prenhall/muscle.jpg

50 myofibrils/fiber (cell)

IV. ProteinsA. structureB. functions! - catalysts (enzymes) - structural (actin/collagen/etc.) - transport (hemoglobin, cell membrane) - immunity (antibodies) - cell signaling (surface antigens)

IV. ProteinsA. structureB. functions!C. designer molecules

If protein function is ultimately determined by AA sequence, why can’t we sequence a protein and then synthesize it?

IV. ProteinsA. structureB. functions!C. designer molecules

If protein function is ultimately determined by AA sequence, why can’t we sequence a protein and then synthesize it?

Folding is critical to function, and this is difficult to predict because it is often catalyzed by other molecules called chaparones

IV. ProteinsA. structureB. functions!C. designer molecules

If protein function is ultimately determined by AA sequence, why can’t we sequence a protein and then synthesize it?

Folding is critical to function, and this is difficult to predict because it is often catalyzed by other molecules called chaparones

Perhaps by analyzing large numbers of protein sequences and structures, correlations between “functional motifs” and particular sequences will be resolved.