Enzymes Overview Quiz

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Questions and Answers

What type of reactions are involved in catabolism?

Redox reactions

Dehydration synthesis reactions

Endergonic reactions

Hydrolytic reactions (correct)

Which of the following describes the energy characteristics of catabolic reactions?

They produce energy without the use of water.

They consume more energy than they produce.

They are always active at ambient temperature.

They produce more energy than they consume. (correct)

What role do enzymes play in metabolic reactions?

They substitute for reactants in metabolic pathways.

They do not influence the rate of reactions.

They help lower the activation energy required. (correct)

They increase the activation energy needed for reactions.

Which process is primarily associated with anabolic reactions?

Dehydration synthesis Signup and view all the answers

What is the primary reason that metabolic reactions typically require enzymes?

To lower the activation energy needed to initiate the reactions. Signup and view all the answers

What is the term for the complete, catalytically active enzyme along with its bound coenzyme or metal ion?

Holoenzyme Signup and view all the answers

Which of the following statements about enzymes is true?

Enzymes lower the activation energy for reactions. Signup and view all the answers

What type of reactions do anabolic enzymes catalyse?

Formation of bonds between molecules Signup and view all the answers

Which characteristic of catalysts is described as recoverable, allowing only small amounts to be used in reactions?

Recoverability Signup and view all the answers

What characterizes endergonic reactions?

High input energy with lower energy release after product formation Signup and view all the answers

What drives anabolic reactions according to the provided content?

Utilization of energy from ATP Signup and view all the answers

How do enzymes affect the activation energy of a reaction?

They provide an alternative pathway and lower the activation energy Signup and view all the answers

Which of the following describes a feature of enzymes in biochemical reactions?

They can reach the reaction equilibrium faster. Signup and view all the answers

What is the primary purpose of enzymes in metabolic reactions?

To catalyze reactions without being altered Signup and view all the answers

Which model suggests that an enzyme's active site changes shape to fit the substrate?

Induced Fit Model Signup and view all the answers

Which type of metabolic reaction is characterized by the consumption of more energy than it produces?

Endergonic reactions Signup and view all the answers

What is the role of a catalyst in a biochemical reaction?

It lowers the activation energy and increases reaction rate. Signup and view all the answers

What governs the binding specificity of enzymes to their substrates?

The 3D arrangement of atoms on the active binding site Signup and view all the answers

What happens to the equilibrium of a reaction when an enzyme is present?

The equilibrium is reached faster but remains unchanged Signup and view all the answers

In the 'Lock and Key' model of enzyme action, what is emphasized?

The rigid structure of the enzyme's active site Signup and view all the answers

What is formed when an enzyme binds to its substrate?

A stable enzyme-substrate intermediate Signup and view all the answers

What is the main class of the enzyme with the commission number 2.7.1.1?

Transferase Signup and view all the answers

Which of the following statements accurately describes the function of cofactors?

Cofactors can be non-protein molecules that assist enzymes. Signup and view all the answers

What distinguishes coenzymes from prosthetic groups?

Coenzymes act as temporary carriers, while prosthetic groups remain attached. Signup and view all the answers

Which metal ion is commonly known as a cofactor for enzymatic reactions?

Iron (Fe) Signup and view all the answers

How does the 'active site' of an enzyme influence its function?

It determines which substrate(s) can bind to the enzyme. Signup and view all the answers

What type of cofactor is NAD (Nicotinamide adenine dinucleotide)?

Coenzyme Signup and view all the answers

What is the role of magnesium ions (Mg^2+) in enzymatic reactions?

They help activate the enzyme for catalysis. Signup and view all the answers

Which of the following statements about vitamins as cofactors is correct?

Vitamins can be precursors for organic cofactors. Signup and view all the answers

What does a lower K_M value indicate about an enzyme's affinity for its substrate?

The enzyme has a higher affinity for the substrate. Signup and view all the answers

In a non-competitive inhibition scenario, how does the V_max value change?

Decreases. Signup and view all the answers

What is the effect of uncompetitive inhibition on K_M?

Decreases. Signup and view all the answers

How does the K_M value change in competitive inhibition?

It increases. Signup and view all the answers

What type of complex is formed during uncompetitive inhibition?

Inactive enzyme-substrate-inhibitor complex (ESI). Signup and view all the answers

In competitive inhibition, how is the substrate binding affected?

It is unaffected. Signup and view all the answers

Which inhibitor type stabilizes the enzyme-substrate complex?

Uncompetitive inhibitor. Signup and view all the answers

What does a low K_i value imply about an inhibitor?

It binds tightly to the enzyme. Signup and view all the answers

What is the role of K_M in enzyme catalysis?

To determine the concentration at which half the active sites are occupied. Signup and view all the answers

Which enzyme is targeted by the drug Lisinopril?

Angiotensin-Converting Enzyme (ACE). Signup and view all the answers

In which type of inhibition is V_max decreased but K_M unchanged?

Non-competitive inhibition. Signup and view all the answers

What indicates effective inhibitor drugs for a given enzyme reaction?

Low K_i values. Signup and view all the answers

Which statement is true regarding the effect of different inhibitors on V_max?

Uncompetitive and non-competitive inhibitors decrease V_max. Signup and view all the answers

What does [Vmax]{.math.inline} represent in a reaction?

The maximum velocity at saturating substrate concentrations Signup and view all the answers

How is the Michaelis constant [KM]{.math.inline} defined?

It is the substrate concentration at 50% of [V<del>max</del>]{.math.inline} Signup and view all the answers

What type of plot is the Lineweaver-Burk Plot derived from?

Taking the reciprocal of the Michaelis-Menten equation Signup and view all the answers

In an Eadie-Hofstee Plot, what does the y-intercept represent?

The maximum reaction velocity [V<del>max</del>]{.math.inline} Signup and view all the answers

What mathematical transformation is used in the Eadie-Hofstee Plot?

Inverting the Michaelis-Menten equation and multiplying by [V<del>max</del>]{.math.inline} Signup and view all the answers

Which of the following statements about [KM]{.math.inline} is true?

It relates to the reaction at half maximal velocity Signup and view all the answers

What characteristic does the Michaelis-Menten curve display in its graphical representation?

A rectangular hyperbola shape Signup and view all the answers

What is the significance of the intercept in a Lineweaver-Burk Plot?

It helps to determine [V<del>max</del>]{.math.inline} and [K<del>M</del>]{.math.inline} Signup and view all the answers

Study Notes

Enzymes

Enzymes are specialized, catalytically active biological macromolecules that act as specific, efficient catalysts of chemical reactions in aqueous solutions.
Most enzymes are globular proteins, but some are RNA molecules, like ribozymes and ribosomal RNA nucleotides.
Enzymes are named by adding "-ase" to the name of the substrate or a phrase describing the action.
Enzymes are classified based on the type of reaction they catalyze (e.g., oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases).
Enzymes have a unique 3D structure, including an active site.
Enzyme activity can be affected by cofactors which are non-protein components:
- metal ions (e.g., Mg2+, Zn2+, Fe2+, Ca2+)
- organic cofactors (coenzymes): often derived from vitamins or other organic molecules.
Enzymes are important because they catalyze (speed up) biochemical reactions, which can be slow otherwise and/or would not occur.
Metabolism consists of anabolism, which involves building complex molecules from simpler ones, and catabolism, which is the breakdown of complex molecules into simpler ones.
Enzymes play a crucial role in both anabolic and catabolic reactions.
Enzymes lower the activation energy required for reactions to occur.
Enzymes bind to the substrate (reactant) at their active site, forming an enzyme-substrate complex that speeds up the conversion of the substrate to product.
The rate of enzyme-catalyzed reactions is affected by several factors, including: temperature, pH, substrate concentration, and enzyme concentration.

Enzyme Kinetics

Enzyme kinetics is the study of the rates of enzyme-catalyzed reactions.
The Michaelis-Menten equation describes the relationship between substrate concentration, enzyme concentration, and reaction rate.
Km is the Michaelis constant, and it represents the substrate concentration at which the reaction rate is half of its maximum.
Vmax is the maximum reaction velocity that can be achieved with a saturating amount of substrate.
Michaelis-Menten kinetics are often analyzed using a "double-reciprocal plot" (Lineweaver-Burk plot).
Enzyme activity can be regulated by inhibitors:
Competitive inhibitors block substrate binding to the active site; by increasing substrate concentration, the inhibition can be reversed..
Non-competitive inhibitors bind to an allosteric site, which alters the enzyme's active site shape; increasing substrate concentration will not reverse the inhibition, the inhibition will stay.
Uncompetitive inhibitors bind only to the enzyme-substrate complex (ES). Changing substrate concentration does not change the inhibition.

Enzyme Inhibition

Enzyme inhibitors reduce enzyme activity.
Competitive inhibition occurs when inhibitor molecules bind to the active site, preventing substrate binding.
Non-competitive inhibition occurs when the inhibitor binds to an allosteric site, changing the enzyme's shape and hindering its function.
Uncompetitive inhibition involves inhibitor binding to the enzyme-substrate complex, reducing the enzyme's ability to produce the product.
Irreversible inhibitors permanently inactivate enzymes, whereas reversible inhibitors can be released from the enzyme.
Enzyme inhibition can be harnessed for therapeutic purposes.

Important Enzymes and Their Functions

(This section requires the data from the OCR'd text) Some examples of specific enzymes and their functions are important in this section but the data is necessary to complete. For example, what enzyme catalyzes what reaction for what disease? Enzyme, substrate, product or reaction are key data points to complete this section.

Enzyme Classification

(This section requires the data from the OCR'd text) Information about enzyme classes as well as type of reactions they catalyze is important here. Add detailed classification examples for a thorough summary.

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Description

Test your knowledge on the structure, function, and classification of enzymes. This quiz covers key concepts such as enzyme activity, cofactors, and the different types of enzymes. Perfect for students delving into biochemistry or molecular biology.