Chapter 15 Biochemistry

Energy of Life Sun energy is converted to chemical energy by plants 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Building energy molecules = anabolism Breaking down molecules for energy = catabolism

Molecules of Life: Carbohydrates Formed from C, H, and O Types: –Sugars = monosaccharides Names end in –ose –Starches = polysaccharide Plant starch = amylose, large granules Animal starch = glycogen, small granules –Cellulose = polysaccharide Different linkages than starches

Molecules of Life: Fats Called lipids Types: –Fatty acids (triglycerides) –Steroids: cholesterol, sex hormones –Fat-soluble vitamins –Waxes Classified by degree of saturation Insoluble in water Usually less dense than water

Molecules of life: Proteins Vital: present in all body tissues Combinations of amino acids –9 are essential amino acids –All have 3-letter abbreviations How many combinations can you make from threonine (Thr), proline (Pro), cysteine (Cys), and leucine (Leu)?

Molecules of life: Protein Structure Primary –Amino acid sequence: long chain Secondary –Pleated sheet –α- helix Tertiary –3-dimensional folding of chain Quaternary –Multiple separate tertiary structures bonded together

Molecules of life: Protein Structure

α-helixPleated sheet Both due to hydrogen bonding!

Molecules of life: Protein Structure Linking proteins together –Primary = peptide bonds (amide linkage) –Secondary Hydrogen bonds –Tertiary, Quaternary Ionic bonds (“salt bridge”) Disulfide bond (covalent) Dispersion forces –Most important for non-polar side-chains

Molecules of life: Protein Structure

Molecules of Life: Special Proteins Enzymes –Catalyze reactions –Lower activation energy: bring reactants into precise proximity –Increase reaction rate –Lower necessary temperature –Not used up in reaction! –Some for catabolism, some for anabolism

Molecules of Life: Nucleic Acids Nucleotides: –Sugar Ribose (in RNA) Deoxyribose (in DNA) –Phosphate PO 4 3- polyatomic ion bonded to sugar Backbone of the DNA –Amine base Purines: adenine (A), guanine (G) Pyrimidines: cytosine (C), thymine (G), uracil (U) in RNA Purines bond with pyrimidines Linked by hydrogen bonding

Molecules of Life: Nucleic Acids

Double helical structure DNA synthesis –Unzipped by enzymes for replication –“Semi-conservative replication” –Sets of nucleotides copied into new strand

Molecules of Life: Nucleic Acids Protein Synthesis –Transcription mRNA: “negative” copy of DNA in nucleus –Translation tRNA: amino acids make protein structure

Molecules of Life: Nucleic Acids

DNA Analysis Paternity Testing –50% of DNA from each parent DNA fingerprinting –Compare evidence to known samples Crime SceneSuspect 1 Suspect 2Suspect 3Suspect 4 Source:

DNA Manipulation Recombinant Genetics