Bio13312 Biochemistry - Lecture Nine - Enzymes And Coenzymes | Attempts: 268

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Elly Crook

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Quizzes Created: 27 | Total Attempts: 11,612

Questions: 14 | Attempts: 268 | Updated: Mar 21, 2023

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Bio13312 Biochemistry - Lecture Nine - Enzymes And Coenzymes - Quiz

To introduce the six main classes of enzymeTo look at the effect of enzymes on reaction energetics. To introduce co-enzymes and co-factors. To consider general mechanisms of catalysis with a detailed case study on serine proteases.

Questions and Answers

1.

Name 3 of the 6 main classes of enzyme.(Your answers will not be assessed, but you can check them in the feedback section below once you've submitted your answer.)
2.

Complete the following sentence:For a favourable reaction, the products have _____ energy than the reactants.
- A.
  
  Lower
- B.
  
  Higher
- C.
  
  The same
Correct Answer
A. Lower

Explanation
In a favorable reaction, the products have lower energy than the reactants. This is because a favorable reaction is exothermic, meaning it releases energy. The reactants start with a higher energy level, and as the reaction progresses, energy is released and the products end up with a lower energy level. This decrease in energy is what drives the reaction forward and makes it favorable.

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3.

What do catalysts do?
- A.
  
  Reduce activation energy
- B.
  
  Increase activation energy
- C.
  
  Make a thermodynamically unfavourable reaction favourable
Correct Answer
A. Reduce activation energy

Explanation
Catalysts are substances that lower the activation energy required for a chemical reaction to occur. By reducing the amount of energy needed for the reaction to start, catalysts increase the rate at which the reaction takes place. They do not change the overall energy change or favorability of the reaction, but rather facilitate the conversion of reactants into products by providing an alternative reaction pathway with lower energy barriers. Therefore, the correct answer is "Reduce activation energy."

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4.

Please fill answer below:The 'pocket' on the enzyme where the substrate fits is called the _____________.

Correct Answer
Active site

Explanation
The "pocket" on the enzyme where the substrate fits is called the active site. This is where the enzyme and substrate interact and undergo a chemical reaction. The active site has a specific shape and chemical properties that allow it to bind with the substrate and facilitate the conversion of the substrate into a product. The active site plays a crucial role in enzyme activity and specificity, as it determines which substrates can bind and be catalyzed by the enzyme.

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4
5.

Tight binding to either an enzyme or product is bad for catalysts.True or False?
- A.
  
  True
- B.
  
  False
Correct Answer
A. True

Explanation
Tight binding to either an enzyme or product is bad for catalysts because it can hinder the catalytic activity. In order for a catalyst to function effectively, it needs to be able to bind to substrates (reactants) and release products efficiently. If the binding is too tight, it can slow down the reaction or even prevent it from occurring altogether. Therefore, tight binding to either an enzyme or product is detrimental to the catalytic process.

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6.

Please complete the following sentence:Combination of a protein and co-factor/co-enzyme is called a ______________.

Correct Answer
holoenzyme

Explanation
A combination of a protein and a co-factor/co-enzyme is called a holoenzyme. The co-factor or co-enzyme is a non-protein molecule that is necessary for the proper functioning of the protein. When the co-factor or co-enzyme is bound to the protein, it forms a functional unit known as a holoenzyme. The co-factor or co-enzyme often acts as a catalyst, assisting the protein in performing its specific biological function. Holoenzymes are essential in many biochemical reactions and are involved in various metabolic processes in living organisms.

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4
7.

Please fill answer below:The protein alone without a co-factor/co-enzyme is called an ______________.

Correct Answer
apoenzyme

Explanation
An apoenzyme refers to a protein that is inactive or nonfunctional without the presence of a co-factor or co-enzyme. In other words, it is the protein component of an enzyme that lacks the necessary non-protein component to carry out its catalytic function. The co-factor or co-enzyme is required to activate the apoenzyme and enable it to perform its specific biochemical reaction.

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4
8.

Please fill answer below: General acid-base catalyst enzymes stabilise unstable charged intermediates by transferring _______ to and from the intermediate – thereby decreasing the free energy of the transition state.

Correct Answer
Protons

Explanation
General acid-base catalyst enzymes stabilize unstable charged intermediates by transferring protons to and from the intermediate. This proton transfer helps to decrease the free energy of the transition state, making the reaction more favorable. Protons act as a key player in enzyme catalysis by facilitating the formation and breaking of chemical bonds, allowing the reaction to proceed more efficiently.

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0
4 1
9.

The ionic interactions between the enzyme bound metal and the substrate can:
- A.
  
  Orient a substrate for reaction
- B.
  
  Stabilise charged reaction states
- C.
  
  Mediate oxidation-reduction reactions
- D.
  
  All of the above
Correct Answer
A. Orient a substrate for reaction

Explanation
The ionic interactions between the enzyme bound metal and the substrate can orient a substrate for reaction. This means that the metal ion can help position the substrate in a specific way that allows for a more efficient and effective reaction to occur. By orienting the substrate, the metal ion can increase the chances of the desired reaction taking place. This is a crucial step in enzyme catalysis as it helps to ensure that the reaction proceeds in the desired direction.

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10.

Serine proteases use a combination of _________ and ________ catalysis to hydrolyse proteins.
- A.
  
  Acid-base and covalent
- B.
  
  Acid-base and metal ion
- C.
  
  Metal ion and covalent
Correct Answer
A. Acid-base and covalent

Explanation
Serine proteases are enzymes that break down proteins through hydrolysis. They use a combination of acid-base and covalent catalysis to facilitate this process. Acid-base catalysis involves the donation or acceptance of protons, which helps in the activation of water molecules for the hydrolysis reaction. Covalent catalysis involves the formation of a transient covalent bond between the enzyme and the substrate, stabilizing the transition state and facilitating the cleavage of the peptide bond. Therefore, the correct answer is acid-base and covalent catalysis.

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Current Version
Mar 21, 2023

Quiz Edited by
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Dec 23, 2015

Quiz Created by
Elly Crook

Bio13312 Biochemistry - Lecture Nine - Enzymes And Coenzymes

Name 3 of the 6 main classes of enzyme.(Your answers will not be assessed, but you can check them in the feedback section below once you've submitted your answer.)

Complete the following sentence:For a favourable reaction, the products have _____ energy than the reactants.

What do catalysts do?

Please fill answer below:The 'pocket' on the enzyme where the substrate fits is called the _____________.

Tight binding to either an enzyme or product is bad for catalysts.True or False?

Please complete the following sentence:Combination of a protein and co-factor/co-enzyme is called a ______________.

Please fill answer below:The protein alone without a co-factor/co-enzyme is called an ______________.

Please fill answer below: General acid-base catalyst enzymes stabilise unstable charged intermediates by transferring _______ to and from the intermediate – thereby decreasing the free energy of the transition state.

The ionic interactions between the enzyme bound metal and the substrate can:

Serine proteases use a combination of _ and catalysis to hydrolyse proteins.