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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
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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
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
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
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 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
