The building blocks of life… Macromolecules The building blocks of life…

Macromolecules Cells are composed of several types of biological macromolecules. These function as energy-storage molecules, structural components, and in information storage, and are primarily composed of carbon, hydrogen and oxygen.

Carbohydrates carbon, hydrogen & oxygen in a 1:2:1 ratio exist as monosaccharides, disaccharides and polysaccharides among the most abundant molecules on Earth

Monosaccharides “single sugars” general formula is (CH2O)n glucose (top) and ribose (bottom) are monosaccharides

Disaccharides “double sugars” formed by dehydration synthesis from two monosaccharides sucrose, maltose, and lactose are all disaccharides

Synthesis of Maltose - glucose -glucose maltose

Polysaccharides straight or branched chains of monosaccharides connected by glycosidic linkages storage (e.g. starch, glycogen) or structural (e.g. cellulose, chitin)

Polysaccharide Structure Images from MIT Biology Hypertextbook, (1996) http://esg-www.mit.edu:8001/esgbio/lm/sugars/sugars.html (3/9/2001)

Proteins proteins are chains of amino acids connected by peptide linkages order of amino acids for a particular protein is determined by the gene which codes for it

Amino Acid Structure all amino acids have the same basic structure “R” group is different for each amino acid amino group carboxyl group

Peptide Linkages cysteine glycine peptide linkage

Levels of Protein Structure Primary the specific sequence of amino acids coded by DNA Protein structure images from the Online Biology Book, M.J. Farabee, (2001) http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookCHEM2.html (3/9/2002)

Secondary the folding or coiling of the amino acid chain caused by interactions between “R” groups -Helix -Pleated Sheet

Tertiary the unique three-dimensional shape of the protein enzymes are globular proteins collagen is a fibrous protein

Quaternary interactions between separate polypeptide chains, or “subunits” hemoglobin is composed of four subunits

Lipids lipids are a group of hydrophobic molecules “neutral fats” are uncharged lipids composed of glycerol and fatty acids fats are solid at room temperature oils are liquid at room temperature steroids and phospholipids are amphiphilic

Steroid Structure steroids all have the same basic structure of four fused hydrocarbon rings cholesterol is used to synthesize many other steroids in the body cholesterol

Phospholipid Structure glycerol backbone has two fatty acids and one charged inorganic phosphate group attached primary component of cell membranes Image from the Online Biology Book, M.J. Farabee, (2001) http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookCHEM2.html (3/9/2002)

Triglycerides triglycerides are neutral fats glycerol is the “backbone” molecule fatty acids attach to glycerol by ester linkages saturated fatty acids have no double bonds between carbons unsaturated fatty acids have at least one double bond between carbons

Triglyceride Synthesis 3 fatty acids glycerol ester linkage triglyceride

Nucleic Acids Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) composed of nitrogen-containing “bases” attached to a backbone of alternating pentose sugars and inorganic phosphate function in information storage (DNA) and transfer (RNA)

“Bases” of DNA & RNA Purines Pyrimidines adenine thymine guanine cytosine uracil

DNA deoxyribose sugar adenine, guanine, cytosine, thymine bases arranged in a double helix Image from the Online Biology Book, M.J. Farabee, (2001) http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookCHEM2.html (3/9/2002)

RNA ribose sugar adenine, guanine, cytosine, uracil bases single-stranded

References MIT Biology Hypertextbook(1996) http://esg-www.mit.edu:8001/esgbio/lm/sugars/sugars.html (3/9/2001) Farabee, M.J., (2001) An Online Biology Book. Chemistry 2: Water and Organic Molecules http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookCHEM2.html (3/9/2002) A.C.D. Labs (2002) ChemSketch (Freeware), available for download at http://www.acdlabs.com/. Used for molecular structure diagrams.