Biological Molecules Carbon as Central Building Block

Carbon Compounds Organic compounds – primarily Carbon atoms – Large, complex molecules essential for life – Contributes to diversity of life Carbon bonding – Has 4 valence electrons – Can form single, double, or triple covalent bonds – Can form straight or branched chains of itself – Can form rings of itself

Palmitic acid

Functional Groups Influence characteristics of molecules – Make polar with addition of charged entities Affect chemical reactions molecules undergo – Allow bond formation between molecules Some of these groups are – – Hydroxyl (R-OH) – Carboxyl (R-COOH) – Phosphate (R-PO 4 ) – Amine (R-NH 2 )

Functional Groups in Action

Large Carbon Molecules Monomers – Small, simple molecules – Amino acid, fatty acid, nucleotide, monosaccharide Polymer – Monomers join via condensation reactions Polypeptides Disaccharides – Polymers break down with hydrolysis reaction Macromolecules -- Formed from large polymers -- Protein, lipids, nucleic acids, carbohydrates

Polymers & Monomers

A= adenosine; T=Thymidine; G= guanosine; C= cytosine

Energy Currency Compounds store energy in chemical bonds Certain ones’ overall structure stores energy – ATP (Adenosine triphosphate) – NADH (Nicotinamide adenine dinucleotide) – NADPH (Nicotinamide adenine dinucleotide phosphate) – FADH 2 (Flavin adenine dinucleotide)

ATP

Molecules of Life Carbohydrates – (CH 2 O) n general formula n = 3–8 monosaccharides – Hundreds of glucose monomers make glycogen (animals) or starch & cellulose (plants) Proteins – Composed of amino acids (C, H, O, N et al) – 20 essential amino acids, differ in –R groups – Amino acids joined via peptide bond between amino side of 1 & carboxyl side of another – Enzymes are protein catalysts

Molecules of Life, continued Lipids – Large, nonpolar organic molecules – Higher ratio of C & H atoms to O atoms than sugar Types – Fatty acids (12-28 C chain with –COOH group) – Triglycerides (3 fatty acids attach to glycerol) – Phospholipids (2 fatty acids attach to phosphate on glycerol’s 3 rd carbon) – Waxes (long fatty acid attaches to long alcohol chain) – Steroids (Four fused carbon rings + functional groups)

Molecules of Life, continued Nucleic acids – Store and transmit important info in the cell DNA: determines traits & directs cell activities RNA: stores/transmits info from DNA Composed of nucleotides – Adenine, guanine, cytosine, thymine or uracil Made of 3 compartments – Phosphate group – 5-C sugar [(deoxy)ribose] – Ring-shaped nitrogenous base