BCHM 270 Lecture Notes - Lecture 4: Pyruvic Acid, Amylase, Antigen

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19 Sep 2018

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Enzymes are typically globular proteins with multiple domains and a complex structure, that act as catalysts for chemical reactions in the body. A typical enzyme can increase reaction rates by 103-108 times than what would occur without a catalyst. The activation energy is lowered through enzyme stabilization of what is known as the transition state, a high energy molecule that usually has a structure in between the substrate and product. We will explore this more later in this module: transition state: a chemical species that has the highest free energy and the lowest concentration of those on the pathway from a substrate to a product. Enzymes possess several essential properties that make them ideal catalysts for biochemical pathways. The active site, where substrate binds is designed for catalysis. Enzymes also have specificity, which means that they can only catalyze one type of reaction on a specific type of substrate.

Related Questions

1. Compared to its energy content at rest, a vertebrate muscle that has just undergone heavy exercise would have:

a. more ATP and more ADP

b. less ATP and more ADP

c. more ATP and less ADP

d. less ATP and less ADP

2. When compared to a lung cell, a muscle cell would possess:

a. more mitochondria

b. more rough endoplasmic reticulum

c. less mitochondria

d. less rough endoplasmic reticulum

3.Enzymes are protein catalysts in organisms' bodies that permit them to carry out chemical reactions at relatively low temperatures. An enzyme is specific because only few kinds of substrate molecules fit in its activity site. Which of the following statements about enzymes is FALSE?

a. enzymes catalyze only a particular reaction of specific substrates

b. enzymes usually work only in a particular pH range

c. enzymes increase the energy of the reactant molecules

d. enzymes bind their substrates and hold them in a particular orientation

4. This process is essential if the two cells produced as a result of mitosis are to have a full complement of genes.

a. Replication c. Nondisjunction

b. Cytokinesis d. Synapsis

33-To stabilize the transition state complex, which of the following must be lowered? A) Initial energy state B) Activation energy C) Net energy change D) The Vmax B) Final energy state 34- Which of the following statements about allosteric enzymes is CORRECT? A The binding of substrate to any active site affects the other active sites B The plot of initial velocity vs. substrate concentration is a straight line C The Keq of the reaction is increased when allosteric activator is bound D The enzymes contains only one polypeptide chain E Allosteric activators bind to all active sites equally 35. Which statement about the two different models proposed to explain enzyme specificity is CORRECT. a. The substrate changes shape when enzyme binds in the Lock and Key Model. b. The enzyme undergoes a covalent modification when bound to substrate in the Lock and Key Model. c. The active site of the enzyme alternates in conformation between opened and closed in the Induced Fit Model. d. The enzyme changes conformation after binding the substrate in the Induced Fit Model. eÂ·The product structure is altered after it has bound to the enzyme in the Induced Fit Model. 36. An enzymatic reaction proceeds with maximal velocity (Vmax) when A. the substrate concentration is equal to that of a competitive inhibitor. B. allosteric effectors are present. C. the enzyme substrate complex is maximal. D. the substrate concentration exceeds that of a noncompetitive inhibitor. E. all of the substrate is bound to the enzyme. 37. Which of the statements below are incorrect? A With all other factors that modify the rate of the enzyme catalyzed reaction remaining constant as we raise the temperature of an enzyme catalyzed reaction there is an initial increase of velocity with temperature. B. The rate of reaction increases with temperature because there is an increasing number of molecules with sufficient energy to pass over the energy barrier which we call the energy of activation C. Reaction rate increases with temperature until a maximum is reached, when the rate of the reaction will suddenly suddenly fall to zero because the enzyme will be denatured and therefore inactive. D. The reaction rate initially increases as temperature rises owing to increased kinetic energy of the reacting molecules E. Enzymes in crease reaction rates due to their ability to lower the energy barriers for reactions F. None of the above 38- Which of the following is true for the induced fit theory of enzyme action? A. The conformation of the substrate changes before binding to the enzyme. B. The active site changes shape during binding of the substrate C. The substrate fits into a preformed active site through a lock-and-key mechanism. D. Enzymes alternate between conformations where the active site is either open or closed. E. The substrate causes a cleft to form in the enzyme where it subsequently binds

Question 1 When energy changes from one form to another, some of the energy that can be used to do work is always lost. The loss of this energy is mostly in the form of _________.
a. heat
b. potential energy
c. kinetic energy
d. light energy
e. mechanical energy

Question 2 Which of the following is exergonic?
a. binding fatty acids and glycerol molecules together to form lipids
b. building proteins from amino acids
c. binding sugars molecules together to form glycogen
d. breaking bonds in starch to release glucose
e. adding a phosphate group to ADP to form ATP

Question 3 The first law of thermodynamics states that:
a. energy can neither be created nor destroyed.
b. the universe is increasing in entropy.
c. all living organisms must eat to derive energy.
d. energy is required to bring molecules into a cell against a concentration gradient.
e. in energy-yielding reactions, matter goes from a more-ordered to a less-ordered state.

Question 4 Which of the following is true of energy?
a. It can be transferred from one form to another with 100 percent efficiency.
b. It can be created.
c. It can be stored in chemical bonds.
d. It can never be stored.
e. It can be released by forming chemical bonds.

Question 5 Metabolism is:
a. the sum of all the energy a cell uses.
b. the sum of all the vitamins a cell contains.
c. the sum of all the enzymes a cell contains.
d. the sum of all the chemical reactions that an organism carries out.
e. the sum of all the ATP a cell contains.

Question 6 Entropy is the measure of ________ in a system.
a. disorder
b. order
c. energy
d. work
e. heat

Question 7 What percentage of the energy stored in glucose are humans cells able to use to do useful work?
a. 37%
b. 100%
c. 15%
d. 52%
e. 48%

Question 8 What is activation energy?
a. the energy gained by living things, allowing them to remain active
b. the energy produced by the breakdown of ATP to ADP.
c. the energy required to initiate or begin a chemical reaction
d. the energy created by enzymes during exergonic reactions
e. the energy lost by living things in the form of heat

Question 9 Which of the following is true of allosteric enzymes?
a. Their activity can be reduced when the product binds the enzyme.
b. Their activity can be reduced when a coenzyme binds to them.
c. Their activity can be reduced when the substrate binds the enzyme.
d. Their activity can be increased when the product binds the enzyme.

Question 10 Which of the following is a true statement about enzymes?
a. They are made of proteins.
b. They are altered by the reactions they catalyze.
c. They increase the energy of activation of chemical reactions.
d. All of the above are true.
e. None of the above is true.

Question 11 What is the energy currency of cells?
a. ADP
b. enzymes
c. glucose
d. vitamins
e. ATP

Question 12 Kinetic energy is ____________, while potential energy is _____________.
a. stored energy; energy that is being used
b. stored energy; energy that can't be used
c. energy that is being used; stored energy
d. energy that can't be used; stored energy

Question 13 The energy released during ________ reactions can be used to drive ________ reactions, and this is called ________ reactions.
a. exergonic; endergonic; coupled
b. endergonic; exergonic; coupled
c. exergonic; endergonic; mutually dependent
d. coupled; mutually dependent; independent
e. endergonic; exergonic; mutually dependent

Question 14 ADP + P + Energy --> ATP Which of the following is a true statement about the chemical reaction above?
a. This is a coupled reaction.
b. This is an exergonic reaction.
c. The product of the reaction contains more energy than that of all of the reactants combined.
d. This is an endergonic reaction.
e. This is an example of a catabolic reaction.

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BCHM 270 Lecture Notes - Lecture 4: Pyruvic Acid, Amylase, Antigen

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