Biochemistry Carbohydrates, Lipids and Proteins Biology 2121 Chapter 2
Biochemistry Biochemistry • Study of chemical composition and reactions of living matter • Biochemical molecules (4 major types) • Organic vs. Inorganic Organic Compounds • Molecules that make up cells and tissues contain carbon • React to form larger molecules – functional groups • Monomers combine to form polymers • Polymers are broken down into monomers
Functional Groups Forming Polymers – Dehydration Synthesis Breaking down Polymers into monomers – Decomposition – Hydrolysis
Carbohydrates 1. Generalcharacteristics • Contains carbon, hydrogen and oxygen • Soluble in water (decreases with size) • Sizes – small single units to larger compounds 2. Function(s) • Energy – 4 kcal/g • Cell membrane – 1-2% of cell mass; cell recognition 3. Structure • Monomer – “monosaccharide” • Polymer – “polysaccharide”
Carbohydrates 1. Monosaccharides • C6H12O6 - 3 isomers (glucose, fructose and galactose) 2. Disaccharides • Formed by dehydration synthesis • Broken-up by hydrolysis 3. Polysaccharides • Starch, Glycogen, Cellulose 6-Carbon Sugars 5-Carbon Sugars
Disaccharides
Polysaccharides • Glycogen – STORED IN THE LIVER • Starches – plants • Cellulose - roughage
Lipids 1. GeneralCharacteristics • carbon, hydrogen and oxygen • Insoluble in water – soluble in other nonpolar substances (alcohol) • Non-polar 2. Function(s) • Energy – 9 kcal/g • Cell membrane, steroids, fat-soluble vitamins 3. Structure • Most – fatty acid tail (H-C chain) that is non-polar
Functions of Lipids
STRUCTURE OF A TRIGLYCERIDE- Neutral Fat • Formation – dehydration synthesis • Singlebonding between carbons – ‘saturated’ • “Ester Bond” • Long FA chains – solid at room temperature • CH2 – fatty acid tails • Animation • Animation II
Triglycerides Unsaturatedand PolyunsaturatedFats • 1-Double bond between the carbon; 2 double bonds (polyunsaturated) • Chains ‘bend’ or form kinks • Plant lipids; olive oil, corn oil, safflower oil • Chains are shorter than saturated fatty acid triglycerides • Liquids at Room Temperature Triglycerides in the Body • Fat deposits; insulation of organs
Phosphorus Group Glycerol 2-Fatty Acid Chains • Phospholipids • BILAYER OF A PLASMAMEMBRANE • Two FAtails; glycerol; phosphate (polar) • Amphipathic– polar and non-polar nature
Steroids CHOLESTEROLIS CLASSIFIED AS A STEROL – LIPID. MADE UP OF ‘FUSED’ CARBON RINGS AND SIDE CHAINS OF MOLECULES A ‘PRECURSOR’ TO OTHER STEROIDS – TESTOSTERONE, VITAMIN D Side-chainsmade each steroid different
Steroids, Lipoid Substances and Lipoproteins Steroids • Estrogen, progesterone and Testosterone – Sex hormones • Vitamin D: produced in skin (UV light); bone growth • Bile Salts: fat digestion and absorption LipoidSubstances • Fat Soluble Vitamins: A (retinal in eyes); E (wound healing); K (blood clotting) Lipoproteins • Transportation of fatty acids and cholesterol in the bloodstream; LDLs and HDLs
Proteins Largemolecules-C,H,O,N and S Body– 10-30% of cell mass Functionsand Examples • Muscle Contraction (actin and myosin) • Enzymes – catalysts • Hemoglobin (oxygen transport) • Collagen and Keratin (parts of connective tissue, hair, nails, etc.) • Antibodies (immunity)
Structure Amino Acid Structure AminoAcid Central ‘C’ Amine Group Hydrogen Carboxyl Group -COOH Acidic Properties 20 different types
Amino Acids - Bonding • Peptidebonds (covalent) between amino acids form ‘dipeptides’ • Formed by dehydration synthesis • Animation
Multiple Peptide Bonds Polypeptide-10 to 2000 + amino acids 4Structuresof proteins 1. Primary • Exact sequence (of amino acids) of the ‘polypeptide chain’ 2. Secondary • Twisting or folding of the polypeptide primary sequence
Primary and Secondary Structures Primary and Secondary Structures Primarystructure SecondaryStructures Stabilized by Hydrogen bonds Alpha helix and Beta pleated sheets Beta Pleated Alpha Helix
Structures of Proteins 3. Tertiary • 3-D shape of a protein • Folds due to bonding between amino acids • S-S bond (disulfide); hydrogen bonds; ionic bonds • ‘Fully functional’ 4. Quaternary • A protein that has more than one polypeptide chain • Hemoglobin
Structural Classes of Proteins 1. Fibrous • Secondary structure; insoluble; very stable • Examples: • Keratin • Collagen- tendons and ligaments (single most abundant protein in the body) • Actinand myosin (muscle tissue) 2. Globular • Tertiary structure; soluble • Examples: • Proteinhormones (GH and insulin) • Enzymes • Hemoglobin and Myoglobin
Denaturation • The function of a protein may be altered by disruptingthe peptide bonds • How? • Increases in temperature • Changes in pH • Animation • Animation II
Enzymes • How Enzymes Work • Feedback Inhibition What is occurring with the substrate in this diagram? A substrate fits into the active site. The substrate may be ‘degraded’ or broken down into smaller parts or smaller substrates put together to form larger substances
Enzyme Activity Enzymes may be 100% protein Some enzymes are Holoenzymes • Protein part and a “cofactor” or non-protein part • Inorganic cofactor : Fe • Organic cofactor: vitamin (coenzyme) Will only work if the cofactor is present
Characteristics of Enzymes • 4. Lower the activationenergy of a chemical reaction
