Biology Chapter 3: Enzymes Flashcards

Questions and Answers

What is a biological catalyst?

A molecule that slows down a chemical reaction

A molecule that speeds up a chemical reaction but remains unchanged at the end (correct)

A molecule that speeds up a chemical reaction and changes at the end

A molecule that is only made of proteins

What are enzymes described as?

Biological catalysts

What type of enzymes operate within cells?

Intracellular

What type of enzymes are secreted by cells?

Extracellular Signup and view all the answers

What shape are enzymes typically folded into?

Globular Signup and view all the answers

What is the active site of an enzyme?

A region where molecules can bind Signup and view all the answers

What is a substrate?

The molecule that binds to the active site of the enzyme Signup and view all the answers

What is the Lock and Key Hypothesis?

The idea that enzymes and substrates fit together precisely Signup and view all the answers

What is the enzyme-substrate complex?

The combined structure of enzyme and substrate Signup and view all the answers

How many types of substrate molecules does an enzyme usually act on?

One type Signup and view all the answers

What does the induced fit hypothesis suggest?

Enzymes change shape slightly to fit substrates better Signup and view all the answers

How do enzymes catalyze reactions?

By facilitating the breakdown or joining of molecules Signup and view all the answers

What does activation energy refer to?

The extra energy needed to convert a substrate into a product Signup and view all the answers

What is the peak of the effect of temperature on enzyme activity?

Enzymes lose shape and activity above a certain temperature Signup and view all the answers

What is the optimum temperature for enzyme activity in most mammals?

Around 37 degrees Celsius Signup and view all the answers

What happens to enzymes at extreme pH levels?

They can denature and lose functionality Signup and view all the answers

What is an enzyme inhibitor?

A molecule that reduces the enzyme's function Signup and view all the answers

What are competitive inhibitors?

Molecules that compete with the substrate for the active site Signup and view all the answers

What defines non-competitive inhibitors?

They bind to the enzyme but not at the active site Signup and view all the answers

What is the turnover rate of an enzyme?

The rate an enzyme converts a substrate into a product Signup and view all the answers

What does the Michaelis-Menten constant (Km) measure?

The substrate concentration needed for half maximum enzyme activity Signup and view all the answers

Study Notes

Enzymes Overview

Biological catalysts speed up chemical reactions without being altered at the end of the process.
Enzymes are proteins functioning as biological catalysts that enhance reaction rates.

Types of Enzymes

Intracellular enzymes operate within cells.
Extracellular enzymes are secreted by cells and catalyze reactions outside, such as digestive enzymes.

Enzyme Structure

Enzymes are globular proteins with a precise three-dimensional shape, ensuring solubility.

Key Concepts

Active site: a specific region where substrates bind to enzymes.
Substrate: the molecule(s) that fit into the enzyme's active site.
Lock and Key Hypothesis: suggests a specific fit between substrate and enzyme shape; modified to account for enzyme flexibility.
Induced Fit Hypothesis: explains how enzymes and substrates adjust their shapes to enhance binding efficiency.

Reaction Mechanics

Enzyme-substrate complex formed through temporary bonds, allowing reaction facilitation.
Each enzyme typically acts on one substrate type, indicating specificity.
Enzymes can catalyze reactions that involve breaking down or joining molecules.

Activation Energy

Activation energy is the energy required to convert substrates into products; enzymes reduce this energy requirement.

Enzyme Activity Factors

Enzyme concentration affects initial reaction rates; more enzymes lead to faster reactions if substrates are abundant.
Substrate concentration influence: increased substrate raises reaction rates until saturation occurs at Vmax.

Temperature and pH Effects

Reaction rates increase with temperature due to increased molecular movement, peaking at optimum levels (typically around 40°C for mammals).
Enzymes denature (lose function) at high temperatures, negatively affecting activity.
Most enzymes operate best at pH 7; extreme pH changes can denature enzymes.

Inhibition Mechanisms

Enzyme inhibitors decrease enzyme activity; effects can be reversible or irreversible.
Competitive inhibitors mimic substrates and compete for the active site, while non-competitive inhibitors bind elsewhere, altering enzyme shape.

End-Product Inhibition

A process where a product inhibits an enzyme's function, slowing down the reaction chain while remaining reversible.

Enzyme Kinetics

Turnover rate describes how quickly an enzyme converts substrates, estimated at around 1000 substrate molecules per second.
The Michaelis-Menten constant (Km) indicates the substrate concentration at which the enzyme operates at half its maximum rate, reflecting enzyme affinity for substrates.

Immobilized Enzymes

Enzymes can be attached to inert materials for reuse, providing cost advantages and increased stability against temperature and pH changes.

Affinity

Higher affinity indicates a stronger interaction between enzyme and substrate, reflected in a lower Km value.

Reaction Rate Measurement

The rate of reaction can be quantified by measuring the amount of product formed per unit time, providing insights into enzyme efficiency.

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Description

Test your knowledge on enzymes with these flashcards. Each card contains key terms and their definitions, focusing on the role of enzymes as biological catalysts. Perfect for students studying biological processes and chemistry.