2-4: chemical reactions and enzymes

Biology

Unit 1: The Nature of LifeChapter 2: Chemistry of Life

2-1: The Nature of Matter 2-2: Properties of Water 2-3: Carbon Compounds 2-4: Chemical Reactions and Enzymes

Ms. PetrucciBiology

Chapter 2: Chemistry of Life• Vocabulary• 2-1

◦ Atom◦ Nucleus◦ Electron◦ Element◦ Isotopes◦ Compound◦ Ionic Bond◦ Ions◦ Covalent Bond◦ Molecule◦ Van der Waals forces

• 2-2◦ Cohesion◦ Adhesion◦ Mixture◦ Solution◦ Solute◦ Solvent◦ Suspension◦ pH Scale◦ Acid◦ Base◦ Buffer

• 2-3o Monomero Polymero Carbohydrateo Monosaccharideo Polysaccharideo Lipido Nucleic Acido Nucleotideo Ribonucleic Acid (RNA)o Deoxyribonucleic Acid (DNA)o Proteino Amino acid

• 2-4o Chemical Reactiono Reactanto Producto Activation Energyo Catalysto Enzymeo Substrate

CHEMICAL REACTIONS

2.4 Chemical Reactions and Enzymes What is a chemical reaction?

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Chemical ReactionsMass and energy are conservedReactants Products2 kinds: energy releasing

(exothermic) and energy absorbing (endothermic)

CHEMICAL REACTIONS ALWAYS INVOLVE CHANGES IN THE CHEMICAL BONDS THAT JOIN ATOMS IN COMPOUNDS.

Exothermic ReactionsReaction in which heat is given off

(Ex. combustion of fuels)

2H2 + O2 2H2O 6

Endothermic ReactionsReaction in which heat is

absorbed (Ex. water is evaporated)

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Activation EnergyEnergy needed to get a reaction

going

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CatalystA substance that speeds up the

rate of a reactionIt works by lowering activation

energy

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EnzymesProteins that act as biological

catalystsThey speed up chemical

reactions that take place in cellsThey are very specific and

usually catalyze only one chemical reaction

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SubstratesThe reactants of enzyme-

catalyzed reactionsThey bind to sites on the enzyme

called active sites Lock and KeyCO2 + H2O H2CO3

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Regulation of Enzyme ActivityTemperature, pH, and regulatory

molecules can affect how well enzymes work

Pepsin works best under acidic conditions (begins protein digestion)

Some are regulated by molecules that carry chemical signals within cells that turn enzymes “on” or “off”

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