Microbial Metabolism and Enzymes
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Questions and Answers

The collision theory states that chemical reactions can occur when atoms, ions, and molecules collide.

True (A)

Catabolism is the breakdown of complex molecules.

True (A)

Anabolism is an exergonic process because it releases energy.

False (B)

Enzymes are encoded by genes.

<p>True (A)</p> Signup and view all the answers

A metabolic pathway can be defined as a sequence of chemical reactions that are catalyzed by enzymes.

<p>True (A)</p> Signup and view all the answers

An increase in temperature can increase the rate of a chemical reaction, according to the collision theory.

<p>True (A)</p> Signup and view all the answers

Metabolism involves both the buildup and breakdown of nutrients within a cell.

<p>True (A)</p> Signup and view all the answers

Microorganisms are responsible for food spoilage.

<p>True (A)</p> Signup and view all the answers

All microbial metabolic pathways are pathogenic.

<p>False (B)</p> Signup and view all the answers

Dental plaque consists entirely of bacteria.

<p>False (B)</p> Signup and view all the answers

Catalysts are biological substances that speed up chemical reactions.

<p>False (B)</p> Signup and view all the answers

Enzymes lower the activation energy of a reaction.

<p>True (A)</p> Signup and view all the answers

The substrate is transformed and rearranged into products, which are then released from the enzyme in an unchanged form.

<p>False (B)</p> Signup and view all the answers

Enzymes have a specific active site that binds to a specific substrate.

<p>True (A)</p> Signup and view all the answers

Enzymes can convert a maximum of 10,000 substrate molecules per second.

<p>False (B)</p> Signup and view all the answers

The name of an enzyme usually ends in -ase.

<p>True (A)</p> Signup and view all the answers

A lyase is an enzyme that catalyzes the removal of atoms without hydrolysis.

<p>True (A)</p> Signup and view all the answers

A holoenzyme is a protein that requires a cofactor for activity.

<p>True (A)</p> Signup and view all the answers

Temperature has no effect on enzyme activity.

<p>False (B)</p> Signup and view all the answers

The rate of an enzymatic reaction is proportional to the amount of enzyme present.

<p>True (A)</p> Signup and view all the answers

Enzymatic activity always increases when the temperature is increased.

<p>False (B)</p> Signup and view all the answers

Competitive inhibitors bind to the active site of an enzyme.

<p>True (A)</p> Signup and view all the answers

Enzymes can be denatured by heat.

<p>True (A)</p> Signup and view all the answers

The optimal pH for an enzyme is always pH 7.

<p>False (B)</p> Signup and view all the answers

Feedback inhibition is an example of allosteric regulation of an enzyme.

<p>True (A)</p> Signup and view all the answers

Enzymes increase the rate of reaction by lowering the activation energy.

<p>True (A)</p> Signup and view all the answers

A ribozyme is an RNA molecule that functions as a catalyst.

<p>True (A)</p> Signup and view all the answers

The substrate concentration does not affect the rate of a reaction.

<p>False (B)</p> Signup and view all the answers

Allosteric inhibition involves the binding of an inhibitor to the active site of an enzyme.

<p>False (B)</p> Signup and view all the answers

Flashcards

Metabolism

The buildup and breakdown of nutrients within a cell, involving chemical reactions that provide energy and sustain life.

Catabolic Reactions

Reactions that break down complex molecules to provide energy and building blocks for anabolism; they are exergonic.

Anabolic Reactions

Reactions that use energy and building blocks to build complex molecules; they are endergonic.

Metabolic Pathways

Sequences of enzymatically catalyzed chemical reactions in a cell, determined by specific enzymes.

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Collision Theory

States that chemical reactions occur when atoms, ions, and molecules collide with sufficient energy.

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Activation Energy

The minimum collision energy required for a chemical reaction to occur.

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Reaction Rate

The frequency of collisions containing enough energy to bring about a reaction, influenced by factors like temperature and enzymes.

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Exergonic Reactions

Chemical reactions that release energy, usually associated with catabolic processes.

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Endergonic Reactions

Chemical reactions that require an input of energy, often associated with anabolic processes.

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Enzymes

Proteins that act as catalysts in metabolic pathways, speeding up reactions without being consumed.

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Catalyst

Substances that speed up chemical reactions without being consumed.

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Substrate

The specific reactant an enzyme acts on during a chemical reaction.

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Enzyme-substrate complex

The temporary complex formed when a substrate binds to an enzyme's active site.

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Turnover number

The number of substrate molecules converted into product by an enzyme per second.

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Enzyme specificity

The ability of an enzyme to choose exact substrates for its catalytic activity.

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Denaturation

The process where proteins lose their structure and function due to extreme conditions.

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Factors influencing enzyme activity

Temperature, pH, substrate concentration, and inhibitors affect enzymatic action.

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Naming enzymes

Enzymes usually end in 'ase' and are classified based on the type of reaction they catalyze.

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Enzymatic Activity

The rate of reaction catalyzed by an enzyme, which increases with temperature until denaturation occurs.

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Optimal pH

The specific pH level where an enzyme exhibits maximum activity, e.g., pH 5.0 for some enzymes.

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Substrate Concentration

Increased substrate concentration can enhance reaction rates until active sites are saturated.

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Competitive Inhibitors

Molecules that compete with substrates for an enzyme's active site, reducing reaction rates.

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Noncompetitive Inhibitors

Molecules that bind to an enzyme at an allosteric site, affecting enzyme function without blocking the active site.

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Allosteric Inhibition

A regulation mechanism where an inhibitor binds to an allosteric site, decreasing enzyme activity.

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Feedback Inhibition

A regulatory mechanism where the end product of a metabolic pathway inhibits an enzyme involved earlier in that pathway.

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Active Site

The specific region of an enzyme where substrate binds and the reaction occurs.

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Ribozymes

RNA molecules that catalyze biochemical reactions, especially in cutting and splicing RNA.

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Study Notes

Microbial Metabolism

  • Metabolism is the buildup and breakdown of nutrients within a cell
  • These chemical reactions provide energy and create substances that sustain life.

Dental Plaque

  • Dental plaque consists of bacteria.

Catabolic and Anabolic Pathways

  • Catabolic pathways break down macromolecules into simpler components, releasing energy.
  • Anabolic pathways build up macromolecules by combining simpler molecules, using energy in the process.
  • Catabolic and anabolic pathways are linked by energy. Catabolic reactions provide energy for anabolic reactions.
  • These processes are linked to the energy storage/release of ATP (adenosine triphosphate).

Microbial Metabolism and Disease

  • Although microbial metabolism can cause disease and food spoilage, many pathways are beneficial, not pathogenic.

Enzymes and Chemical Reactions

  • Catalysts speed up chemical reactions without being altered.
  • Enzymes are biological catalysts.
  • Enzymes act on specific substrates, lowering activation energy.
  • Substrate contacts the enzyme's active site to form an enzyme-substrate complex.
  • Substrate is transformed and rearranged into products, released from the enzyme.
  • The enzyme is unchanged and can react with other substrates.

Enzyme Mechanisms

  • The images provide a graphical visualization of the enzyme mechanism.

Enzyme Specificity and Efficiency

  • Enzymes have specificity for specific substrates.
  • Turnover number is the number of substrate molecules an enzyme converts to a product per second (generally 1 to 10,000).

Enzyme Names

  • Enzyme names usually end in "-ase" and are grouped based on the reaction they catalyze.
  • Examples include: oxidoreductase (oxidation-reduction), transferase (transfer functional groups), hydrolase (hydrolysis), lyase (removal of atoms without hydrolysis), isomerase (rearrangement of atoms), and ligase (joining of molecules; uses ATP).

Holoenzymes

  • Holoenzyme, the whole enzyme, consists of an apoenzyme (inactive protein portion) and a cofactor (nonprotein activator).
  • Coenzymes are a type of cofactor.

Factors Influencing Enzyme Activity

  • Temperature: High temperatures denature proteins, affecting enzyme activity. Ideal temperatures exist for most enzymatic reactions.
  • pH: Extreme pH values also denature proteins in enzymes. Ideal pH values exist for optimal enzyme activity.
  • Substrate Concentration: Increasing substrate concentration increases reaction rates up to a point where all active sites are saturated.
  • Inhibitors: Substances that reduce enzyme activity.
    • Competitive inhibitors: Fill the active site, competing with the substrate.
    • Noncompetitive inhibitors: Interact elsewhere on the enzyme (allosteric site), changing the active site's shape.

Feedback Inhibition

  • The end-product of a reaction allosterically inhibits enzymes earlier in the pathway.
  • It's a regulatory mechanism to control the amount of product.

Ribozymes

  • RNA that function as catalysts, cutting and splicing RNA.

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Microbiology Introduction Chapter 5 PDF

Description

Explore the fascinating world of microbial metabolism, including catabolic and anabolic pathways, and the role of enzymes in chemical reactions. This quiz examines how these processes are linked to energy storage and release through ATP, as well as the impact of microbial metabolism on health and disease.

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