Chapter 2: Chemistry of Life

Building Blocks of Matter The basic unit of matter is the atom Atoms are made of subatomic particles: protons (+), electrons (-), and neutrons Protons and neutrons reside in the nucleus Electrons move around in orbitals outside of the nucleus Atoms of the same element but with different neutrons are isotopes Carbon-12, Carbon-13, Radioactive Carbon- 14

Building Blocks of Matter Two or more elements can combine to form compounds (H2O) Ionic bonds hold a compound together by a transfer of an electron leading to charged elements (NaCl) Covalent bonds involve sharing of electrons between elements (H2O)

Building Blocks of Life Element – Substance that can’t be broken down into simpler chemical substances. Carbon - the element of life as it can combine with other elements and with itself to form long complex structures. It must have 4 bonds.

Macromolecules Macromolecules – big molecules Monomers – small subunits (building blocks) of large molecules, ex. Glucose is the monomer of starch, a polymer Polymer- made of many molecules, ex. proteins, nucleic acids

Carbohydrates Main source of energy for living organisms (glucose) Organisms store energy as complex carbohydrates called starches

Carbohydrates Monosaccharide – single sugar. Polysaccharide – large molecules formed from monosaccharides.

Lipids Composed predominately of carbon and hydrogen atoms (limited oxygen) Includes fats, oils, waxes, steroids Composed of glycerol and fatty acids

Lipids

Nucleic Acids Composed of monomers called nucleotides Composed of 5-C sugar, phosphate group, and a nitrogenous base Joined together to form nucleic acids: ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) Store and transmit hereditary (genetic) information

Nucleic Acids

Proteins Contain nitrogen, carbon, oxygen, and hydrogen Monomer: amino acids 20 different amino acids are found in nature, leads to significant diversity in proteins

Proteins Proteins are the doers of life Controls rates of reactions Regulate cells processes Form bones and cells Transport substances into and out of cells

Proteins

Organic Macromolecules Compound Subunit(s) Elements Function Examples Carbohydrates   Glucose or sugar C, H, O Main energy source Structure glucose, starch, cellulose, glycogen Lipids (fats & oils) Glycerol and 3 fatty acids Energy storage Protective coverings Phospholipids, steroids Proteins Amino acids C,H,O,N, & usu. S Muscles/ bones/ structure Control reaction rates Regulation Transport substances Fight disease Insulin, enzymes, hemoglobin, muscle fibers Nucleic acids Nucleotides C, H, O, N, P Store and transmit genetic information DNA, RNA

Chemical Reactions Chemical reactions involve the breaking of bonds in reactants and the formation of new bonds in products Those entering the reaction are reactants Products are produced by the reaction

Chemical Reactions Equations must balance. Atoms are not created or destroyed, just rearranged. Example: 2H2 + O2 2H2O Reactants are on the left and enter into the reaction. Products are on the right and result from the reaction. Metabolism – All of the chemical reactions that occur within an organism.

Energy in Reactions 2H2 + O2 2H2O Occurs naturally, releasing energy The reverse reaction: 2H2O 2H2 + O2 requires so much energy it rarely occurs

Chemical Reactions Activation energy – energy needed to get a reaction started. Catalyst – substance that speeds up the rate of a chemical reaction. Enzymes – proteins that speed up chemical reactions because they lower the activation energy. Enzymes provide a site where reactants can be brought together. (This reduces the energy needed for the reaction, called activation energy). Substrate – the reactant(s) the enzymes fit.

Enzymes

Enzymes

Enzymes Enzymes can be affected by any variable that affects chemical reactions including temperature and pH Enzyme activity are regulated by cells often by turning them on or off

Characteristics of Enzymes Specific (a special shape; use induced fit) Reusable Not consumed (used) in the reaction Affected by factors such as pH and temperature. Enzymes are specific because they are proteins made by folding into a 3-D shape (linked to their function).

Properties of Water Although water is neutral, it does have polarity Water molecule is polar because of uneven distribution of electrons The oxygen end has a slight negative charge The hydrogen end has slight positive charge

Properties of Water Due to its polarity, water can hydrogen bond with itself (attract itself) Weaker than ionic bonding (NaCl) Cohesion is attraction of molecules of same substance (beads of water) Adhesion is attraction of molecules of different substances (water and graduated cylinder)

Properties of Water Water is not always pure, it is often found as a mixture (material composed of two or more elements or compounds that are not chemically combined) If the materials are evenly distributed it is called a solution The substance that is dissolved is the solute The substance that dissolves is the solvent

Properties of Water When material does not dissolve a suspension is formed Example: blood cells and water The movement of the water keeps the small particles suspended

Acids and Bases pH – A measure of how acidic or basic a solution is. Scale is 0 to 14. Below 7 is acidic. Above 7 is basic. 7 is neutral Acidic solutions have higher concentration of H+ ions than pure water (pH 7) Basic solutions have a lower concentration of H+ ions than pure water Buffers – prevent sharp, sudden changes in pH

Acids and Bases

Acids and Bases