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This chapter explores the importance of water and carbon compounds in biochemistry. Topics covered include the properties, hydrogen bonding, cohesion, adhesion, capillary action, and density of water, as well as the formation of salts. It also discusses the characteristics and functions of organic compounds, including carbohydrates, lipids, proteins, and nucleic acids.
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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