Chapter 5

Macromolecules

Macromolecules

Four Classes 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids

Polymer

Chain of linked monomers

polymer monomer

Carbohydrates sugar

Proteins amino acids

Nucleic acids nucleotides

Composite molecule

Lipids glycerol + fatty acid(s)

Bonds

macromolecule bond/link type

Carbohydrates glycosidic linkage

Lipids ester linkage

Proteins peptide bond

Nucleic acids phosphodiester bond

Chemical Reactions

Dehydration synthesis (Condensation) - remove a water molecule, polymerize

Requires enzymes HO 1 2 3 H OH H

H20

short polymer

1 2 3 4HO H

longer polymer

Chemical Reactions

Hydrolysis - add a water molecule, depolymerize

HO H

HO H

H2O

H OH

Metabolism

Anabolism - synthesize molecules polymerization dehydration

Catabolism - breakdown molecules depolymerization hydrolysis

Carbohydrates

CHO sugars function: energy storage (fuel for cellular

work), most are hydrophilic three groups:

monosaccharides disaccharides polysaccharides

Monosaccharides

empirical formula = (CH2O) n n = 3 to 7 n=5 pentose n=6 hexose Examples of hexoses (C6H12O6)

glucose fructose galactose

Disaccharides

monosaccharides disaccharide

glucose + glucose = maltose

glucose + galactose = lactose

glucose + fructose = sucrose

formed through dehydration

Formation of Disaccharaides

glucose glucose maltose

glucose fructose sucrose

Polysaccharide

Covalently bonded glucose unitsGlycosidic linkage - covalent bond between glucose units

amylose(unbranched)

amylopectin

Starch(plants)

Glycogen(animals)

glycogengranules

Cellulosecell wall

cellulose microfibrils in a plantcell wall (about 8O molecules)

unbranched β glucosepolymer

unbranched, alternating OH groupsfound in plant cell walls

Chitin

Glucose plus a nitrogen apendage

Present in exoskeleton of arthropods

used to make strong and flexible surgical thread

Lipids

CHO Function: long-term energy storage

fats other lipids: phospholipids, steroids, pigments

water-insoluble, nonpolar

Fats

Glycerol + fatty acid (s) monoglyceride diglyceride triglyceride

glycerol - 3C alcohol

monoglyceride(palmitic acid)

trigryceride (triacylglycerol)

Fats, cont.

ester linkage - bond between carboxyl (f.a.) and hydroxyl (glycerol)

fatty acids saturated unsaturated

esther linkage

Saturated Fatty Acids

maximum number of H no double/triple bonds usually solid ex. animal fats

(butter, lard)

Unsaturated Fatty Acids

usually liquid 1 double bond

monounsaturated more than 1 double bond

polyunsaturated

ex. Oils (nut and seed) hydrogenation causes it

to solidify peanut oil peanut butter

fats yeald 9 cal/gr

oleic acid

Other Lipids

Phospholipids phosphate + 2 f.a. + glycerol

Steroids Hormones and cholesterol

Pigments chlorophylls xanthophylls carotenes anthocyanins

fatty acids

glycerol

phosphate

choline

hydrophilic

hydrophobic

Proteins

CHON Function: diverse

structures, contraction, storage, defense, transport, messengers, enzymes

monomer: amino acid

Proteins cont.

amino acids (20): most contain -central C -amino group -carboxyl group -H atom -functional group (R)

glycine alanine valine leucine isoleusine

methionine phenylalanine tryptophan proline

serine threonine cysteine tyrosine aspargine glutamine

asparctic ac. glutamic acid lysine arginine histine

Non polar

polar

electricallycharged

R-group

acidic basic

Proteins cont.

*Peptide bonds *between 2 amino acids *dehydration reaction

protein synthesis

side chain

backbone

Levels of Protein Structure The following determine the shape of the

protein (polypeptides): primary secondary tertiary quaternary

Primary Structure of a Protein

+H3N(amino end)

C OH-O(carboxyl end)

amino acid subunits

Start: N-terminus (amino) End: C-terminus (carboxyl)

Secondary Structure of a Protein Bending and H-bonding to form coils and folds forming

alpha helices (coils) and beta pleated sheets (folds)

α- helix

β pleated sheet

Tertiary Structure of a Protein

overall conformation of the polypeptide hydrophobic interactions ionic and hydrogen bonds disulfide bridges

polypeptidebackbone

Quaternary Structure of a Protein Relationship between 2 or more polypeptides

that make up the protein

Protein Conformation

Altering any level will change the final conformation

denaturation - unravel the protein caused by several different factors

Nucleic Acids

CHONP Function: store information monomer - nucleotide

ex. DNA, RNA RNA Genomics - branch of biotech

concerned with mapping and sequencing DNA (genomes)

Nucleotide

Phosphate + sugar + N-base phosphodiester bond between phosphate and sugar

DNA

nucleus Deoxyribonucleic acid double strand A, G, C, T

nucleotide: phosphate + sugar + N-base

The sequence of nitrogenous bases in DNA carries genetic information

stretches of DNA are genes

RNA

cytoplasm Ribonucleic acid single strand RNA

nucleotide: phosphate + sugar + N-base

A, G, C, U

N-bases Purines (A, G)Pyrimidines (C, T, U)Purine-Pyrimidine

A = T

C = G

Activity: DNA

What will the other strand be?

DNA

A

G

C

T

?

?

?

?

DNA

5'

3'

Activity

What will the RNA strand be?

DNA

A

G

C

T

?

?

?

?

RNA

5'

3'

The End