Overview
This lecture covers the fundamentals of chemical reactions, types of reactions in the human body, and the roles and properties of enzymes as biological catalysts.
Chemical Reactions and Notation
- A chemical reaction involves forming, breaking, or rearranging chemical bonds, or transferring electrons between atoms.
- Chemical notation uses symbols and abbreviations to represent chemical reactions.
- Chemical equations list reactants (starting substances) on the left and products (resulting substances) on the right.
- Arrows in equations indicate reaction direction: one-way for irreversible and two-way for reversible reactions.
Forms of Energy in the Human Body
- Chemical energy is stored in chemical bonds.
- Electrical energy results from the movement of charged particles.
- Mechanical energy is transferred directly between objects.
- Chemical energy from food is converted into ATP, which powers electrical, mechanical, and synthetic processes in the body.
Types of Chemical Reactions
Catabolic Reactions
- Catabolic reactions break large molecules into smaller ones, typically releasing energy.
- The specific process is called hydrolysis, which uses water to break chemical bonds.
- Examples: digesting food, recycling cellular components, and breaking down glycogen to glucose.
Anabolic Reactions
- Anabolic reactions join small subunits to form larger molecules, requiring energy input.
- The specific process is dehydration synthesis, which removes water to create new bonds.
- Examples: building proteins from amino acids, forming enzymes, and synthesizing glycogen from glucose.
Enzymes and Activation Energy
- Atoms must collide with enough energy (activation energy) for a reaction to occur.
- Enzymes lower activation energy, speeding up chemical reactions so life processes can occur efficiently.
Properties of Enzymes
- Enzymes are biological catalysts, most are proteins ending in "ase."
- They are highly specific to their substrates due to shape compatibility.
- They do not alter reactants or products and are reusable for multiple reactions.
Key Terms & Definitions
- Chemical Reaction — Process involving the making or breaking of bonds or electron transfer.
- Reactants — Substances that enter into a chemical reaction.
- Products — Substances produced by a chemical reaction.
- Catabolic Reaction — Reaction breaking large molecules into smaller ones (hydrolysis).
- Anabolic Reaction — Reaction building larger molecules from smaller ones (dehydration synthesis).
- Enzyme — Protein catalyst that lowers activation energy and speeds up reactions.
- Activation Energy — Minimum energy needed to start a chemical reaction.
- Substrate — Reactant molecule acted on by an enzyme.
Action Items / Next Steps
- Review and memorize the types and properties of chemical reactions.
- Study examples of catabolic and anabolic reactions in the human body.
- Learn key enzyme functions and substrate specificity.