biochemical reactions chemistry in biology chapter 6
TRANSCRIPT
Biochemical ReactionsChemistry in Biology
Chapter 6
Review• What is the smallest unit of
matter?
• How are atoms and elements related?
• Are living organisms comprised of these same elements?
• How is chemistry related to the growth and survival of living organisms?
• Atoms: building blocks of matter
• Protons: positively charged particles
• Electrons: negatively charged particles
• Neutrons: particles with no charge
• Elements: pure substance that cannot be broken down into other substances by physical or chemical means
• Compounds: pure substance formed when two or more different elements combine
Atoms, Elements, Compounds
Chemical Bonds
• Covalent Bonds: bond formed when electrons are shared
• Ionic Bonds: electrical attraction between two oppositely charged atoms or groups of atoms (called ions)
Chemical Reactions
• The process by which atoms or groups of atoms in substances are reorganized into different substances.
• Reactants: starting substance (left side)
• Products: substance formed during reaction (right side)
Energy of Reactions• Most compounds in living things cannot
undergo chemical reactions without energy.
• Activation Energy: minimum amount of energy needed for reactants to form products in a chemical reaction
• Sometimes a chemical reaction must absorb energy for the reaction to start, usually in the form of heat (endothermic).
Energy of Reactions
http://www.docbrown.info/page03/3_51energy.htm
Enzymes
• Catalyst: substance that lowers the activation energy needed to start a chemical reaction
• Enzymes: special proteins that are biological catalysts, speed up the rate of reactions
Enzymes
• Enzymes are very specific, each particular enzyme can only catalyze one reaction.
• The reactants that bind to an enzyme are called substrates.
• The specific location where a substrate binds is called the active site.
• Temperature and pH can alter enzyme structure.
Acids and Bases
• Acids: substances that release hydrogen ions (H+) when dissolved in water
• Bases: substances that release hydroxide ions (OH-) when dissolved in water
pH• The amount of hydrogen ions or
hydroxide ions in a solution determines the strength of an acid or a base.
• pH: measure of concentration of H+
• Majority of biological processes carried out by cells occur between pH 6.5 and 7.5.
Buffers
• Mixtures that can react with acids or bases to keep the pH within a particular range.
• In cells, buffers keep the pH between 6.5 and 7.5.
Biochemical Reactions
• Allow organisms to grow, develop, reproduce, and adapt
Questions• What are the factors that affect the rate
of biochemical reactions?
• Construct a cause and effect model showing how temperature, pH, and enzymes are used to control chemical reactions in living organisms. ex) If _____ happens then _____ will happen as a result.
• Describe the importance of enzymes to living organisms?