AP Biology - Enzymes (3.1-3.3)

Cell's Metabolism

Chemical reactions that take place within cells.
Ex. Anabolism, Catabolism.

Metabolic Pathway

A series of chemical reactions that either builds a complex molecule (anabolic reaction) or breaks down a complex molecule into simpler compounds (catabolic reaction).

Anabolic Reaction (Anabolism)

A reaction that builds new molecules and/or stores energy (Ex. Dehydration Synthesis)

REQUIRES ENERGY

Catabolic Reaction (Catabolism)

A reaction that breaks down molecules into small ones. (Ex. Hydrolysis)

RELEASES ENERGY (DOES NOT REQUIRE ENERGY)

Kinetic Energy

Energy due to motion

Potential Energy

Energy referred to the potential to do work.

Free Energy

Measure of Energy available to do work

Chemical Energy

Potential energy existing within chemical bonds; released when bonds are broken.

Gibbs Free Energy

Usable Energy; Energy available to do work - AKA Free Energy

Exergonic Reaction

A chemical reaction that releases energy.

EX: Catabolic Reactions

THINK: EXergonic = Energy EXiting.

Endergonic Reaction

A chemical reaction, in which free energy is absorbed from the surroundings (REQUIRE INPUT OF ENERGY).

EX: Anabolic Reactions

Activation Energy

Small amount of energy input needed for all chemical reactions to occur.

Enzyme

A type of protein that speeds up a chemical reaction (acts as a biological catalyst) in a living thing.

Function of Enzymes

Speed up chemical reactions by lowering activation energy.

Explain how enzymes speed up chemical reactions

Enzymes function as catalysts to speed up chemical reactions by lowering the initial amount of energy needed to begin the reaction.

Enzymes are usually made of _________.

Enzymes are usually made of Proteins.

T/F: Are enzymes reusable?

TRUE: Enzymes are reusable.

NAMING: Enzymes usually end with the suffix _____.

-ase.

Enzymes usually end with the suffix -ase.

Active site of Enzyme

The region of an enzyme where substrate molecules bind and undergo a chemical reaction.

Substrate

The reactant on which an enzyme works; binds to active site.

Explain why enzymes usually facilitate only one type of reaction.

"STRUCTURE DETERMINES FUNCTION!"

Due to each enzyme's unique structure, it can only facilitate one specific type of reaction, as its unique structure determines its unique function.

T/F: The active site of the enzyme is specific to the substrate it binds with.

TRUE: The active site of the enzyme is specific to the substrate it binds with as the enzymes unique structure determines its unique function, meaning it can only facilitate specific reactions.

In the context of enzymes, explain the type of relationship substrate concentration has with the reaction rate of the enzymes.

THINK: Substrate Concentration and Reaction Rates have a _________ relationship.

In the context of enzymes, substrate concentration and the speed of the reaction rate have a direct relationship, meaning:

⬆️ Substrate Concentration = ⬆️ Speed of Reaction Rate
--AND--
⬇️ Substrate Concentration = ⬇️ Speed of Reaction Rate

The greater the concentration of substrates, the faster the reaction rate; the same is true if the concentration of substrates is decreased.

Competitive Inhibition

A process by which a chemical substance has a shape that fits the active site of an enzyme and competes with the substrate for the active site, effectively inhibiting the enzyme.

BIG IDEA: Active Site blocked by Competitive Inhibitor.

Noncompetitive Inhibition

Describes when the inhibitor binds with the enzyme at a site other than the active site (known as the allosteric site) and inhibits the enzyme by altering the shape of the active site.

BIG IDEA: The active site is modified due to a noncompetitive inhibitor acting on the allosteric site, making it difficult for the substrate to fit into the active site.

Does competitive and noncompetitive inhibition affect the reaction rate of the enzyme? Explain.

Yes, competitive and noncompetitive inhibition affect the reaction rate of the enzyme as they both affect the substrate concentration by decreasing it, thus slowing down the reaction rate of the enzyme.

Denaturation of Enzyme

Occurs when the enzyme is outside the "optimal range" and the enzyme's shape changes making it now less effective or ineffective)

Changes in the tertiary structure of the enzyme.

Environmental Factors that can lead to Enzyme Denaturation

1) Change in Temperature (Increasing Heat outside of Optimal Range)

2) Change in pH

3) Exposure to metal ions

How dos denaturation affect enzyme function?

The Catalytic (Catalysis) ability of the enzyme is lost/significantly decreased, making the enzyme less efficient. However, in some cases, the affects of denaturation are reversible.

Note: Denaturation only affects the active site; NOT THE WHOLE ENZYME.