Four Major Types of Biological Macromolecules Type of Polymer Monomers making up Polymer Example I. Carbohydrates (Polysaccharides) Monosaccharides Sugars, Starch, Cellulose II. Lipids Fatty acids and glycerol Fats, steroids, cholesterol III. Proteins Amino acids Enzymes, structural components IV. Nucleic Acids Nucleotides DNA, RNA

I. Carbohydrates Made from monomers called monosaccharides (simple sugars) Short term energy Glucose: most common, used directly in cellular respiration to make ATP (energy)

Figure 5.3 The structure and classification of some monosaccharides

Disaccharides

Polysaccharides: Complex Carbohydrates 3 major types made from monomers of glucose: Starch: energy storage in plants Glycogen: energy storage in animals Cellulose: structural molecules in plants

Figure 5.6 Storage polysaccharides

Figure 5.7a Starch and cellulose structures

Figure 5.7b,c Starch and cellulose structures

Figure 5.8 The arrangement of cellulose in plant cell walls

II. Lipids Not true polymers Composed of mostly glycerol and fatty acids Includes Fats: energy storage Phospholipids: membranes Steroids: hormones, cholesterol

Fats are made of one glycerol and three fatty acids

Double bonds, fewer H atoms No Double bonds, maximum H atoms Double bonds between carbons cause kinks in hydrocarbons. H2C CH2 H2C CH2 H2C CH Kink CH H2C Figure: 4.8b Caption: (b) The double bond(s) found in an unsaturated hydrocarbon produce a “kink” (shown exaggerated) in an otherwise straight chain. The icon on the right indicates that one of the hydrocarbon tails in a phospholipid is unsaturated. Exercise Draw figures analogous to those in part (b) for a hydrocarbon chain containing two double bonds. (Hydrocarbon chains like these are called polyunsaturates because poly means “many.”) CH2 H2C Unsaturated fatty acid Saturated fatty acid CH2 H2C Double bonds, fewer H atoms No Double bonds, maximum H atoms

Figure 5.11 Examples of saturated and unsaturated fats and fatty acids

Phospholipids are made of one phosphate group and 2 fatty acids Phospholipids are amphipathic

Figure 5.13 Two structures formed by self-assembly of phospholipids in aqueous environments   

Figure 5.14 Cholesterol, a steroid Steroids consist of a complex carbon ring structure Figure 5.14 Cholesterol, a steroid    

Figure 4.8 A comparison of functional groups of female (estradiol) and male (testosterone) sex hormones

III. Proteins H2N C R H O OH Made from monomers called amino acids Very different structures, very different functions H2N Amino group C Side chain R H O OH Carboxyl

The R groups of an amino acid may be hydrophobic or hydrophilic

Amino acids are joined together by a dehydration reaction H2N H C O OH Carboxyl group N CH3 Peptide bond Amino H2O +

Many amino acids joined together = Polypeptide chain N-terminus C-terminus H H O H H O H H O H H O H H O H H O H H O H H O H N C C N C C N C C N C C N C C N C C N C C N C C OH H CH3 CH2 CH2 CH2 CH CH2 CH2 OH C OH H3C CH3 SH O Figure: 3.9b Caption: (b) Amino acids can be linked into long chains by peptide bonds.  OH

The sequence of amino acids in the polypeptide chain = the primary structure of a protein

Hydrogen bonds between amino acids leads to the secondary structure of a protein Two common secondary structures are the -helix and -pleated sheet

Further folding of the polypeptide chain contributes to the tertiary structure of a protein

The joining of more than one polypeptide chain leads to the quaternary structure of proteins

Heat (energy) can break up the structure of a protein

Table 5.1 An Overview of Protein Functions

IV. Nucleic Acids Nucleic acids (DNA and RNA) are made of monomers called nucleotides Nitrogenous base Nitrogenous base Phosphate group Phosphate group Sugar Sugar

Figure 5.29 The components of nucleic acids

Space-filling model of Figure 3.17b 5´ 3´ 5´ 3´ 5´ 3´ T A T DNA is a double helix. A G C G C C G C G T A A T T A A T C G C G G C G A T A T T A T A C G C G Figure: 3.17b Caption: (b) Complementary base pairing twists DNA into a double helix. T A T A G C T A A T G C C G T A A T 5´ 3´ 5´ 3´ 5´ 3´ Cartoon of base pairing Cartoon of double helix Space-filling model of double helix

Nucleic acids store the information to make proteins

Figure 5.30 The DNA double helix and its replication