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Chapter 3 Biochemistry Water Water – makes up 70% of a cell’s weight – Most intracellular rxns occur in the aqueous environment Properties: – Inorganic Molecule – nonliving and does not contain C – H2O – Polar compound – one that has a more positive charge on one side, and a more negative charge on the other – Makes a great solvent; dissolves ions and other polar molecules easily Water – Hydrogen Bonds – weak attraction between a molecule with a negative charge (ex oxygen) and a hydrogen atom – Cohesion – tendency of the molecules of a substance to stick together – Adhesion – attractive force between unlike substances – Capillary action – ability to spread through narrow pores or tubes against gravity Is water more or less dense at 4°C (ice)? Salts Salts – formed when an acid reacts with a base – Na+ ions help nerves carry messages Carbon Compounds Organic Compounds – contain C and living – Exceptions: graphite, diamonds, CO2 Carbon exhibits bonding power of 4 – Most often bonds with hydrogen, oxygen, nitrogen, or to itself and forms chains Carbon Compounds Polymer – complex molecules consisting of repeated monomers – Macromolecules – large polymers Monomer - A single, repeated molecule unit – Ex: a sugar molecule in starch Carbon Compounds Condensation Reaction (dehydration synthesis) – process of bonding two monomers together by the removal of a H2O Hydrolysis – process of breaking apart a complex molecule by the addition of a water Carbon Compounds I. Carbohydrates – the most abundant of all biological molecules – Made up of C, H, and O Monosaccharide (simple sugars) – one monomer of sugar – Cannot be hydrolyzed into a smaller unit, C6H12O6 – Ex: Glucose, Fructose, Galactose Carbon Compounds Isomers – Compounds that have the same exact molecular formula but differ in structure and function Disaccharide – two monosaccharides joined together by a condensation reaction forming a double sugar, C12H22O11 – Ex: Sucrose, Maltose, Lactose Polysaccharides – complex carbohydrates made up of many joined monosaccharides – Ex: Cellulose, Starch, Glycogen Carbon Compounds II. Lipids (fats) – Fatty hydrocarbon compounds also composed of C,H,O – Ex: Fats, oils, wax 4 Kinds of Lipids 1. Triglycerides – neutral fats having 3 fatty acid tails attached to a glycerol molecule – Ex: Butter, Lard, Vegetable Oils Carbon Compounds 2. Phospholipids – a lipid composed of glycerol, 2 fatty acid tails, and a head containing a phosphate group Hydrophilic – water loving carboxyl end Hydrophobic – water fearing hydrocarbon end Carbon Compounds 3. Waxes – long-chain fatty acids linked to long chain alcohols – Ex: Wax coating on cherries, wax in human ears 4. Sterols (steroids) – Complex lipids comprised of 4 interlocking carbon rings – Ex: hormones, cholesterol, nerve tissue, plant poisons Carbon Compounds III. Proteins – organic compound composed of amino acids, CHON – Most diverse group of the large biological molecules Amino Acids – building blocks of proteins, 20 kinds Carbon Compounds – Peptide bonds – bond that links two amino acids together Ex: Dipeptide – 2 amino acids joined together Polypeptide – 3 or more amino acids – Enzymes – Class of proteins which speed up specific metabolic reactions by lowering the activation energy Carbon Compounds IV. Nucleic Acids – complex organic molecules made up of monomers of nucleotides – Ex: DNA – Deoxyribonucleic Acid RNA – Ribonucleic Acid Carbon Compounds Nucleotides – Small organic compound comprised of: – 1. Phosphate group – 2. 5-C sugar (pentose) – ribose or deoxyribose – 3. nitrogen base – Adenine Guanine Cytosine Thymine