What processes and characteristics need to occur for something to be considered “living”? Excretion : getting rid of waste Secretion : releases usable materials Reproduction Growth Use energy Metabolize : carry out chemical reactions Has Genetic material Made up of CELLS!

How do our cells carry out all of the necessary processes of life? ENZYMES! (2.5)

Proteins 4 levels of structure The sequence of amino acids (specifically the R-groups) determines the overall shape of a protein The function of any proteins is dependent upon its overall shape When a protein is denatured, the intermolecular bonds are broken, compromising the shape of the protein, and thereby losing its function.

Characteristics of Enzymes Enzymes are a specific type of protein (polypeptide) Quaternary level structure Speed up all types of chemical reactions by reducing the activation energy required Do not get destroyed during reactions, but get re-used over and over again. Are highly specific in their behavior which is determined by the shape of the enzyme Are affected by pH and temperature Approximately 1,300 enzymes in the human cell. DNA = instructions for life ; Enzymes = workers that carry out those instructions Rubisco is the most abundant enzyme in the world.

What is ACTIVATION ENERGY? Chemical reactions are due to molecules physically colliding with one another Molecules must have enough energy to break and re-form bonds (chemical reaction) ACTIVATION ENERGY: the amount of energy required for a chemical reaction to occur

Enzymes (Catalyst): speed up a reaction by stressing the bonds in the reactants, providing another chemical pathway that has a lower activation energy (Ea) Enzymes only work to speed up reactions that are already occurring, they cannot produce reactions that would not normally occur.

Metabolic reactions would not be possible without enzymes Body temperature: 37⁰C (98⁰F) Polymers could not be digested without enzymes Enzymes remain unchanged after a reaction has occurred Enzymes are reused Speed up reaction by reacting w/ reactants to make a more unstable intermediate -→ speeding up formation for products

Example: Catalytic Converters as Catalysts Catalytic converters speed up the reaction that converts harmful exhaust gases into harmless products Nitrogen oxide and carbon monoxide are converted to carbon dioxide and nitrogen gas

How are enzymes used in our bodies? Some enzymes have 1 specific function, while others are involved in various types of reactions. Example Functions: Copy DNA Digest food Obtain & metabolize energy from food Synthesis of proteins Blood clotting Getting rid of wastes

(the shape of the active site determines the function of the enzyme)

How do enzymes work? – OLD MODEL

The Induced Fit Model of How Enzymes Work

Why do enzymes stop working?

What factors affect the activity of an enzyme? Temperature pH Concentration (amount) of substrate