Enzymes and Their Functions

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Questions and Answers

What happens to an enzyme when it is denatured?

It retains its original shape.

It increases its reaction rate.

It may unfold and lose its function. (correct)

It becomes more efficient.

Which of the following factors can lead to enzyme denaturation?

Decrease in pressure.

Changes in temperature. (correct)

Addition of coenzymes.

Increase in substrate concentration.

How does an increase in temperature affect enzyme activity up to a certain point?

Enzyme activity stops entirely.

Enzyme activity increases due to more collisions. (correct)

Enzyme activity decreases due to denaturation.

Enzyme activity fluctuates unpredictably.

What is the effect of extreme pH changes on enzymes?

They can alter the ionization of amino acids. Signup and view all the answers

Why do pepsin and trypsin exhibit different optimal pH values?

They are found in different locations in the body. Signup and view all the answers

What occurs when the temperature exceeds an enzyme's optimal level?

The enzyme may become denatured. Signup and view all the answers

Which ion is NOT typically implicated in enzyme denaturation?

Sodium Signup and view all the answers

How does a denatured enzyme affect the rate of a biochemical reaction?

It decreases the reaction rate. Signup and view all the answers

What is the optimal pH for pepsin to function effectively?

Acidic pH Signup and view all the answers

What happens when a substrate can produce two different products through different enzymes?

The substrate can be processed by multiple metabolic pathways. Signup and view all the answers

Why is enzyme specificity important in metabolic pathways?

To ensure efficiency and precision in biochemical reactions. Signup and view all the answers

What type of regulation occurs when a cell no longer needs the product from an enzyme?

Feedback inhibition Signup and view all the answers

What does competitive inhibition involve?

A molecule competing with the substrate for an active site. Signup and view all the answers

How can enzyme concentrations be regulated within a cell?

Through genetic regulation and the degradation of already produced enzymes. Signup and view all the answers

What role do proteins play in the metabolism of cells?

They act as enzymes facilitating biochemical reactions. Signup and view all the answers

Which of the following statements about enzyme production is accurate?

Enzyme production can be increased or decreased based on cellular needs. Signup and view all the answers

Which vitamin is associated with the coenzyme NAD+?

Niacin Signup and view all the answers

What is the function of NADH in cellular respiration?

To carry two electrons Signup and view all the answers

Which of the following coenzymes is used in photosynthesis?

NADP+ Signup and view all the answers

What does FAD convert into after being reduced?

FADH2 Signup and view all the answers

What is the result of the reaction NAD+ + 2H?

NADH + H+ Signup and view all the answers

What role does NADPH play in photosynthesis?

Reducing CO2 to carbohydrate Signup and view all the answers

Which vitamin corresponds to Coenzyme A?

Pantothenic acid Signup and view all the answers

Which of the following accurately describes FAD?

It is similar to NADP+ in function. Signup and view all the answers

What is the primary function of enzymes in biochemical reactions?

To speed up chemical reactions Signup and view all the answers

What characterizes enzymes in terms of specificity?

They are specific for one type of reaction or related reactions Signup and view all the answers

What happens at the active site of an enzyme?

The substrate binds and forms an enzyme-substrate complex Signup and view all the answers

What does the Induced Fit Theory propose about the interaction between an enzyme and its substrate?

The enzyme alters its shape for a better fit with the substrate Signup and view all the answers

Why are enzymes considered reusable in chemical reactions?

They return to their original shape after releasing products Signup and view all the answers

How are enzymes typically named?

By incorporating 'ase' to the name of the substrate Signup and view all the answers

What is the role of the enzyme-substrate complex in enzyme function?

To enable the chemical reaction to occur more easily Signup and view all the answers

What occurs after the reaction involving an enzyme is completed?

The enzyme remains unchanged and is available for reuse Signup and view all the answers

What describes the effect of competitive inhibition on enzyme activity?

It physically blocks the substrate from reaching the active site. Signup and view all the answers

How does noncompetitive or allosteric inhibition affect an enzyme?

It binds to the allosteric site and changes the enzyme's shape. Signup and view all the answers

What stabilizes the active form of an enzyme in allosteric regulation?

The binding of an allosteric activator. Signup and view all the answers

What is an example of feedback inhibition?

Heat inhibiting its own production in a thermostat system. Signup and view all the answers

What role do poisons play in enzyme regulation?

They bind irreversibly to enzymes, inhibiting their function. Signup and view all the answers

Which intermediate chemicals are produced in the hypothetical metabolic pathway leading to chemical D?

B and C Signup and view all the answers

What occurs during feedback inhibition in a metabolic pathway?

The final product inhibits the activity of earlier enzymes. Signup and view all the answers

What happens to the enzyme's active site when an allosteric inhibitor binds?

The active site is altered and cannot function properly. Signup and view all the answers

Study Notes

Enzymes Overview

Enzymes are organic catalysts that speed up biochemical reactions.
They are specific to particular reactions or related reaction groups.
Many reactions cannot happen without the appropriate enzyme.
Enzymes are commonly named with the suffix "ase" reflecting their substrate (e.g., dehydrogenases remove hydrogen).

Key Terms

Enzyme: Proteins that act as catalysts in biochemical reactions.
Substrate: The reactant(s) acted upon by enzymes.
Active Site: The specific region on an enzyme where the substrate binds.
Enzyme-Substrate Complex: The temporary complex formed when a substrate binds to the active site of an enzyme.

Lock and Key Model

The shape of the enzyme's active site is complementary to the substrate.
Only substrates that fit the active site can bind, illustrating enzyme specificity.

Induced Fit Theory

The enzyme's active site may change shape to fit the substrate closely during binding.
This change can lower the energy required to break or form bonds in chemical reactions.
Enzymes do not form permanent bonds with substrates and are reusable.

Denaturation

High temperatures, extreme pH changes, heavy metals, and UV radiation can denature enzymes.
Denaturation alters the enzyme's shape, impacting its function.
If denaturation is mild, some enzymes can regain their original structure.

Effects of Temperature

Increased temperatures enhance molecular movement, raising the rate of enzyme-substrate interactions.
However, excessively high temperatures can cause denaturation, reducing enzyme functionality.

pH Levels

Each enzyme has an optimal pH, determined by its typical biological environment (e.g., pepsin in acidic stomach conditions, trypsin in neutral small intestine).
Altering an enzyme's pH can disrupt ionic interactions and hydrogen bonding, resulting in a loss of shape and function.

Metabolic Pathways

Metabolism is the sum of all chemical reactions within cells, with specific enzymes catalyzing each step.
Each substrate may be processed by multiple enzymes through metabolic pathways.

Regulation of Enzymes

Enzyme activity can be regulated by genetic mechanisms, adjusting the concentration of enzymes.
Regulation can be achieved via feedback inhibition, competitive inhibition, and noncompetitive (allosteric) inhibition.

Competitive Inhibition

A molecule similar in shape to the substrate competing for the active site, preventing substrate binding.

Noncompetitive/Allosteric Inhibition

An inhibitor binds to a site other than the active site, altering the shape of the enzyme and its active site functionality.

Allosteric Regulation

Activators: Bind to allosteric sites to stabilize the active form of an enzyme.
Inhibitors: Stabilize the inactive form of the enzyme.

Feedback Inhibition

A product of a metabolic pathway can inhibit its own production to maintain homeostasis (e.g., heat inhibiting thermoregulation).

Coenzymes

Many vitamins act as coenzymes, assisting enzyme function.
Significant coenzymes include NAD+, FAD, and NADP+, which serve as electron carriers in metabolic processes.

NAD+ (Nicotinamide Adenine Dinucleotide)

Involved in cellular respiration, it carries two electrons and facilitates oxidation reactions by removing hydrogen atoms.

FAD (Flavin Adenine Dinucleotide)

Can be reduced to FADH2 and transfers electrons in metabolic reactions.

NADP+ (Nicotinamide Adenine Dinucleotide Phosphate)

Functions similarly to NAD+, carrying electrons involved in photosynthesis and facilitating the reduction of CO2 into carbohydrates.

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Description

This quiz covers the essential concepts of enzymes, including their role as catalysts in chemical reactions. It highlights the specificity of enzymes, their organic nature, and the importance of the right enzyme for reactions to occur. Test your knowledge on key terms and functions related to enzymes.