Biology Enzymes and Metabolism: Key Concepts and Reactions

What type of reaction does the hill diagram represent?

Anabolic/endergonic, requiring energy input.

What is metabolism?

All of the chemical reactions in a cell or organism.

What is catabolism?

The breakdown of molecules that releases energy (exergonic reaction).

What is an example of a catabolic reaction?

Hydrolysis.

What is anabolism?

The synthesis of molecules that requires energy (endergonic reaction).

What is an example of an anabolic reaction?

Dehydration synthesis.

What is a catalyst?

A substance that increases the rate of a chemical reaction without being consumed.

How do enzymes function as catalysts?

They position reactants to facilitate reactions and lower the activation energy.

What are metabolic pathways?

A series of chemical reactions where the product of one reaction becomes the substrate for the next.

What is the difference between cyclic and linear metabolic pathways?

Cyclic pathways, like the Krebs Cycle, repeat, while linear pathways, like glycolysis, progress in one direction.

What is the role of enzymes in metabolic pathways?

Each reaction in a metabolic pathway is catalyzed by a specific enzyme.

What is the active site of an enzyme?

The part of an enzyme where a substrate molecule attaches.

What is a substrate?

The specific substance on which an enzyme acts.

What is the induced fit model?

The change in shape of the active site when a substrate binds, allowing for a snug fit.

Why are enzymes specific to particular substrates?

Enzymes have an active site shaped to fit specific substrates.

What happens to the enzyme after a reaction?

The enzyme is not consumed and can be used again.

What is activation energy (EA)?

The energy required to start a chemical reaction.

How do enzymes affect activation energy?

Enzymes lower the activation energy required for a reaction to proceed.

What is the catalytic cycle of an enzyme?

The process where an enzyme binds to a substrate, facilitates a reaction, and releases the product while returning to its original shape.

What is an example of a digestive enzyme?

Chymotrypsin, produced by the pancreas to hydrolyze proteins.

What is the reaction catalyzed by sucrase?

The conversion of sucrose and water into glucose and fructose.

Can enzymes be used more than once?

Yes, enzymes are not consumed in reactions and can catalyze multiple reactions.

Is the reaction catalyzed by sucrase catabolic or anabolic?

Catabolic, as it involves the breakdown of sucrose into simpler sugars.

What is a catabolic reaction?

A reaction that breaks down more complex molecules and usually releases energy.

What role do enzymes play in reactions?

Enzymes reduce the activation energy barrier, facilitating chemical reactions.

What factors can affect enzyme activity?

Temperature and pH can change the shape and activity of enzymes.

What is the optimal temperature for thermophiles?

Thermophiles have an optimal temperature that allows for maximum enzyme activity.

What happens to enzyme activity at high temperatures, such as 50°C?

The rate of reaction goes to 0 due to denaturation of the enzyme.

What is the optimal pH range for most enzymes?

The optimal pH is near neutral, typically between 6 and 8.

Which enzyme works in the human stomach?

Pepsin is the enzyme that hydrolyzes proteins in the stomach.

What is the effect of increased sucrase activity?

Increased sucrase activity would speed up the conversion of sucrose to glucose and fructose.

How do cells control enzyme activity?

Cells control enzyme activity by making more or fewer enzyme copies and activating enzymes when needed.

What is a competitive inhibitor?

A substance that reduces enzyme activity by entering the active site in place of the substrate.

How does penicillin act as a competitive inhibitor?

Penicillin mimics the substrate of transpeptidase, inhibiting bacterial cell wall synthesis.

How can competitive inhibition be overcome?

By increasing the concentration of the substrate.

What is a noncompetitive inhibitor?

A substance that reduces enzyme activity without entering the active site, changing the enzyme's shape instead.

How can noncompetitive inhibition be addressed?

Increasing enzyme concentration may help, but sometimes nothing can be done.

What determines if an enzymatic reaction is reversible?

It depends on how quickly or easily the inhibitor can dissociate from the enzyme.

What types of bonds make inhibition less likely to be reversible?

Covalent bonds make inhibition less likely to be reversible compared to hydrogen bonds.

Give an example of a drug that acts as an enzyme inhibitor.

Ibuprofen inhibits an enzyme involved in the production of pain-increasing prostaglandins.

What is the role of protease inhibitors in HIV treatment?

Protease inhibitors target a key viral enzyme to inhibit HIV replication.

How do pesticides like malathion work?

They target specific enzymes in insects, causing irreversible inhibition and death.

What is the effect of nerve gases on enzymes?

Nerve gases bind to active sites of enzymes involved in nerve impulse transmission, leading to paralysis and death.