Biochemistry Atoms, Elements, and Compounds Chemical Reactions Water and Solutions The Building Blocks of Life

Review Atoms are the building blocks of matter. Protons- positively charged particles Neutrons- have no charge Protons and neutrons are located in the nucleus of the atom Electrons- negatively charged particles Move around the nucleus in energy levels

Elements An element is a pure substance that cannot be broken down into other substances by physical or chemical means. Isotopes- atoms of the same element that have the same number of protons and electrons but have a different number of neutrons Compounds- a pure substance formed when two or more different elements combine

Chemical Bonds The forming of chemical bonds stores energy and the breaking of chemical bonds releases energy for an organism’s life processes (growth development, reproduction) Covalent bonds- chemical bond that forms when electrons are shared Compounds that held together by covalent bonds are called molecules

Ionic bond- an electrical attraction between two oppositely charged atoms or groups of atoms van der Waals Forces- When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together (water)

Chemical Reactions The process by which atoms or groups of atoms in substances are reorganized into different substances Chemical bonds are broken and formed Production of heat or light, and formation of a gas, liquid, or solid Reactants- starting substances Products- substances formed during reaction

Energy of Reactions Activation energy- the minimum amount of energy needed for reactants to form products in a chemical reaction This reaction is exothermic and released heat energy.

Energy of Reactions This reaction is endothermic and absorbed heat energy.

Enzymes Catalyst- a substance that lowers the activation energy needed to start a chemical reaction Enzymes- biological catalysts Not used up in the reaction pH and temperature affect enzyme activity

Enzymes Substrates- the reactants that bind to the enzyme Active site- the specific location where a substrate binds on an enzyme

Water’s Polarity Molecules that have an unequal distribution of charges are called polar molecules Hydrogen bond- a weak interaction involving a hydrogen atom and a fluorine, oxygen, or nitrogen atom

Mixtures Solution (homogenous mixture)- has the same composition throughout Solvent- a substance in which another substance is dissolved. Solute- the substance that is dissolved in the solvent Heterogeneous- the parts remain distinct, can identify individual parts

Acids Bases Substances that release hydroxide ions (OH–) when dissolved in water The more OH– released the more basic the solution Basic solutions have pH values higher than 7 Buffer- mixtures that can react with acids or bases to keep the pH within a particular range Substances that release hydrogen ions (H+) when dissolved in water The more H+ released the more acidic the solution pH- the measure of concentration of H+ in a solution Acidic solutions have pH values lower than 7.

Organic Chemistry The study of organic compounds Almost all biological molecules contain the element carbon. Macromolecules- large molecules formed by joining smaller organic molecules together Polymers- molecules made from repeating units of identical or nearly identical compounds linked together by a series of covalent bonds

Carbon Has four electrons in its outermost energy level. One carbon atom can form four covalent bonds with other atoms. Carbon compounds can be in the shape of straight chains, branched chains, and rings.

Carbohydrates Compounds composed of carbon, hydrogen, and oxygen in a ratio of one oxygen and two hydrogen atoms for each carbon atom—(CH2O)n Monosaccharides- short chains of carbohydrates (simple sugars) Disaccharides- two monosaccharides linked together Polysaccharides- longer carbohydrate chains

Carbohydrates Energy sources for organisms Provide structural support in cell walls of plants and in the hard shells of shrimp, lobsters and some insects

Lipids Molecules made mostly of carbon and hydrogen Fats, oils, waxes Main function: to store energy Triglyceride- fat when solid, oil when liquid

Saturated fats- carbon atoms cannot bond with any more hydrogen atoms Unsaturated- carbon atoms can bond with more hydrogen atoms Phospholipids- fats with more than one double bond in the tail Responsible for structure and function in cell membrane Steroids- (cholesterol and hormones) provides starting point for other important lipids, estrogen and testosterone

Proteins Made of small carbon compounds called amino acids Amino acids- small compounds that are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur. 20 different amino acids Proteins are made of different combinations of amino acids joined together by peptide bonds

Protein: Structure Amino acid chains fold into three-dimensional shape A protein might contain many helices, pleats, and folds, held by hydrogen bonds

Protein: Function Provide structural support Transport substances inside and between cells Communicate signals within the cell and between cells Speed up reactions Control cell growth

Nucleic Acids Complex macromolecules that store and transmit genetic information Nucleotides- repeating subunits that make up nucleic acids Carbon, nitrogen, oxygen, phosphorus, and hydrogen 3 units: a phosphate, a nitrogenous base, and a sugar

Nucleic Acids 2 types found in living things DNA = “genetic code” Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) DNA = “genetic code” Stores all the information to grow, reproduce, and adapt RNA uses the information stored in DNA to make protein