Chapter 6: Chemistry in Biology

Atoms Atoms are the smallest unit of an element Three particles Protons (+ charge) Electrons (- charge) Neutrons (no charge) Nucleus contains protons and neutrons

Elements Pure substance made of only ONE type of atom Arranged in periodic table using atomic # Atomic # = # of protons OR electrons Atomic mass = # of protons + # of neutrons

Isotopes Atoms of the SAME element that have a different # of neutrons Ex: Carbon-12, Carbon-13, Carbon-14 C-13 and C-14 have MORE neutrons (weigh more) than C-12

Radioactive Isotopes Radioactive isotopes have unstable nuclei that break down at a constant rate over time Uses for radioactive isotopes Dating of rocks and fossils Kills bacteria on food Kills cancer Trace movements of substances within the body

Compounds A substance formed by combination of two or more atoms in definite amounts or ratios Ex: Water (cmpd name), H2O (chem. formula) Carbon dioxide (CO2) – necessary in large amounts, Carbon monoxide (CO) – deadly in large amounts

Compounds, cont. Chemical properties of cmpd are TOTALLY different than the elements within it Ex: NaCl (Na-sodium-is a soft metal; Cl-chlorine-is a green poisonous gas) forms table salt!!!

Solutions Solute – the substance that is dissolved Solvent – the substance in which the solute dissolves Ex: Salt Water Solute = Salt Solvent = Water

pH Scale Scale measuring amount of H+ (really H3O+) Ranges from 0-14 Neutral: (pH = 7) Human blood Pure water Acidic: (pH = 0-6.9) Lemons/lemonade Stomach acid Basic: (pH = 7.1-14) Baking soda Bleach

Acid and Base Buffers Weak acids/bases that help prevent sharp pH changes Ex: blood has a buffer (to keep it at 6.5-7.5 pH) Ex: When you drink lemonade, your body produces a buffer to make sure you blood pH doesn’t lower to acidic levels!

Water-Why does it support life? Like a Buffer for Temperature Change Cohesion: Water sticks to itself (makes drops) Adhesion: Water sticks to OTHER molecules (travels thru plants) Hydrogen bonding: (Polar ) Type of bond which holds water molecules together Universal Solvent (Saliva)

The Element Carbon Symbol: C Forms Organic Compounds Compounds that make up living things Also called: Macromolecules Polymers

Carbon, cont. Carbon has 3 chemical advantages: 1) Can make up to 4 covalent bonds 2) Can bond with many elements 3) Can form long chains -by bonding to itself -forms millions of different molecules

Carbon Compounds Made of two or more smaller molecules Monomer + Monomer = Polymer Polymers = puzzle Monomers = puzzle pieces Four main types: 1) Carbohydrates 2) Nucleic acid 3) Proteins 4) Lipids

Carbohydrates Made of C, H, and O in a 1:2:1 ratio Monomers Dimers Monosaccharide Examples: glucose, fructose, galactose Dimers Disaccharides Examples: sucrose and lactose Polymers Polysaccharides Examples: starch, glycogen, chitin, and cellulose

Uses for Carbohydrates Main source of energy for body functions (through digestion) Used to build nucleic acids Structural purposes (cell membrane)

Carbohydrates

Carbohydrates (Chitin and Cellulose)

Lipids (Fats) Made of C, H, and O (phospholipids have P) Triglyceride Monomers: 1 Glycerol, 3 Fatty Acid Chains Examples: Fats found in adipose tissue Phospholipid Monomers: 1 Glycerol, 2 Fatty Acid Chains Example: Molecules found in cell membrane Steroid Monomers: 4 Carbon ring structure Example: cholesterol, testosterone, estrogen, and other hormones

Lipids

Lipids

Lipids Testosterone Progesterone Cholesterol

Lipids Uses: Store Energy Long-Term (blubber) Part of Cell Membranes (phospholipids) Waterproof Coverings (feathers) Chemical Communication (hormones)

Lipids, cont. Four main categories: 1) Fats – butter, margarines, crisco 2) Oils – olive, veggie, canola, corn 3) Waxes – candles, cosmetics, duck’s feathers surrounded by this 4) Steroids – used in communicating b/t cells

Nucleic Acids Made of C, H, O, N and P Monomer: Nucleotide (3 Parts) Uses: To store hereditary info To pass hereditary info on to offspring Phosphate Sugar Nitrogen Base

Nucleic Acid Parts DNA (Information Storage) 5 Carbon Sugar : Deoxyribose Nitrogen Bases: A, T, G, C Phosphate RNA (Information Transfer) 5 Carbon Sugar: Ribose Nitrogen Bases: A, U, G, C Phosphate Sugar Nitrogen Base

DNA RNA

Protein Made of C, H, O, S, and N Monomer: Polymer: Amino acids (20 needed in human body) Polymer: Polypeptide Chain  Protein Amino acids are held together by a peptide bond

Proteins Uses: Enzymes: Control rate of reactions Regulate: cell processes Structure: form bones/muscle Transport: substances in or out of cells Fight disease: Antibodies

Glycerol AND fatty acids Monomers and Polymers Macromolecule Monomer Polymer Carbohydrate Monosaccharide Polysaccharide Protein Amino acid Proteins Lipid Glycerol AND fatty acids Lipids Nucleic acid Nucleotide DNA or RNA

Chemical Reactions Chemical reactions are the breaking and forming of chemical bonds Reactants- original elements or compounds Products- ending elements or compounds

ATP Structure Adenine High Energy Bonds Adenosine Ribose Phosphates

Energy in Chemical Reactions Organisms need E to carry out Reactions All an Organism’s Chemical Reactions = Metabolism Where do they get Energy (E)? Plants – photosynthesis/sun Animals – eating food/consuming others

Energy of Reactions (Rxns) Reaction Types Energy Releasing Reaction is spontaneous (not fast, necessarily) Activation energy – energy need to get the reaction started At the end of the reaction, energy is released into the environment Energy Absorbing Rxn is not spontaneous Activation energy- energy needed to get the rxn started At end of the rxn, energy is absorbed from environment

Energy Reaction Diagrams

Enzymes Catalyst for the reaction (speeds up it’s rate) Substrate (reactant) enters the active site of the enzyme to form an enzyme-substrate complex After the rxn, the product leaves The enzyme remains unchanged

Enzymes

Action of Enzymes Speeds up the reaction by lowering activation energy

Enzymes uses DNA replication Digestion (enzymes in your stomach, saliva) Water removal (from food) Carbon dioxide removal (from blood) Fat breakdown (detergents)