metabolism and enzymes 2

Metabolism

A network of enzyme-catalyzed reactions in cells or organisms.

Anabolism

Builds complex molecules (e.g., protein synthesis, glycogen formation, photosynthesis).

Catabolism

Breaks down complex molecules (e.g., digestion, cellular respiration).

Active Site

Region where the substrate binds; complementary shape ensures specificity.

Enzyme-Substrate Specificity

Only one type of substrate fits the enzyme's active site.

Induced Fit Model

the best explanation of how enzymes catalyse reactions.

Collision Theory

Reactions occur when particles collide with enough energy and the correct orientation.

Factors Increasing Collision Rate

Higher temperature increases kinetic energy and movement; higher substrate concentration leads to more collisions with active sites; immobilized substrates/enzymes keep reactants in close proximity.

Enzyme Denaturation

Extreme temperature or pH changes alter enzyme shape, causing the active site to no longer bind substrate and the enzyme to lose function.

Temperature Effects on Enzyme Activity

Low temperature results in slow reaction rate; optimum temperature results in fastest reaction rate; too high temperature causes denaturation.

pH Effects on Enzyme Activity

Each enzyme has an optimum pH level, and large deviations cause denaturation.

Substrate Concentration Effects

More substrate increases reaction rate until all active sites are saturated.

Activation Energy

Minimum energy needed for a reaction.

Enzymes Lowering Activation Energy

Enzymes allow reactions to occur efficiently at body temperature.

Intracellular Enzymes

Function inside the cell that produces them (e.g., mitochondrial enzymes for respiration).

Extracellular Enzymes

Function outside the cell (e.g., digestive enzymes secreted into the gut).

Endotherms

Animals that maintain constant body temperature through metabolic heat (e.g., mammals, birds).

Metabolism & Heat Production

Heat is an inevitable consequence of metabolism because energy transfer is not 100% efficient.

Linear Pathway

Chemical reactions occur in a straight sequence (e.g., glycolysis in respiration).

Cyclic Pathway

Chemical reactions repeat in cycles (e.g., Krebs cycle in respiration, Calvin cycle in photosynthesis).

Competitive Inhibition

Inhibitors bind to the active site, preventing the substrate from binding (e.g., Statins inhibit enzymes in cholesterol production).

Non-Competitive Inhibition

Inhibitors bind to an allosteric site, altering enzyme shape.

Feedback Inhibition

The end product inhibits the first enzyme in a metabolic pathway.

Mechanism-Based Inhibition

Irreversible binding to an enzyme's active site.

Metabolism

A network of enzyme-catalyzed chemical reactions occurring in a cell or organism.

Active Site

The region of an enzyme where a substrate binds and is converted into products.

Collision Theory

Chemical reactions occur when particles collide with sufficient energy and correct orientation.

Induced Fit Model

Model explaining enzyme function where the active site slightly changes shape to fit the substrate.

Competitive Inhibition

Inhibitor binds to the active site, preventing the substrate from entering.

Allosteric Site

A site on an enzyme where molecules bind to regulate enzyme activity, changing its active site shape.

Activation Energy

The minimum energy required for a reaction to occur.

Endotherms

Animals that maintain a constant body temperature through metabolic heat production.

Enzyme Inhibition

The process of reducing or stopping enzyme activity through inhibitors.

Statins

Competitive inhibitors that lower cholesterol by blocking specific enzymes.

Penicillin

An antibiotic that inhibits bacterial cell wall synthesis by targeting transpeptidase.

Enzyme-Substrate Complex

Temporary binding of an enzyme and substrate during a reaction.

Denaturation

Permanent change in enzyme shape due to extreme temperature or pH, preventing function.

Saturated (Active Sites)

Condition where all enzyme active sites are occupied, causing reaction rate to plateau.

Where is the optimal temperature on a temp. graph?

The highest point of the graph

Anything above the optimal temp. will be __________

denatured

Where is the optimal pH on a pH graph?

The middle of the spike/highest point on the graph

an increase or decrease in pH __

decrease in enzyme activity. A large change will denature the enzyme.

Reaction rate continues to increase as substrate concentration increases, until all of the enzymes' active sites are _.

saturated