60 terms

BIO 201 UNCW Chapter 6 Brooker

the compounds that an enzyme "works" on
can push or pull a reversible reaction; decreasing=pull; increasing=push
energy carrier molecules
transports energy in the form of high-energy chemical bonds or excited electrons
the most universal and important of the energy carrier molecules
reactions that are endergonic; large, energy rich compounds are synthesized from small, energy-poor precursors; ex:) photosynthesis
reactions that are exergonic; broken down for energy into smaller, simpler, molecules; ex:) cellular respiration
equillibrium ratio
the ratio of product to reactant under standard conditions
chemical equillibrium
when a reaction is running at the same rate in both directions
a compound that forms between the start and conclusion of a reaction or pathway
end product
the compound formed at the end of the pathway
protein catalysts
activation energy
a chemical reaction occurs when molecules collide with enough energy to break or reform bonds; the minimal energy for this is called _________________
active site
a crevice in the enzyme surface; the site of interaction between enzymes and substrates
induced fit model
once the substrate enters the active site, the site can put strains on the bonds of substrate models; this speeds up the reaction
allosteric site
it's the site where another substance combines with the enzyme at a site other than the active site; reaction alters the shape of the enzyme, which alters enzyme's catalyctic activity
allosteric inhibition
used to control an enzyme that is normally in the "on" position; alters the shape of the active site and turns it "off"
feedback inhibition
occurs when an ongoing process is inhibited by an end product of that process; ex:) mechanical
the sum of all the chemical reactions that take place in a cell
reactions that release energy
reactions that require energy
coupled reactions
when a reaction that releases energy is put with a reaction that requires energy
2nd law of thermodynamics
no energy conversion is 100% efficient; some energy is lost as heat with each transfer; with each successive energy conversion, the orderliness of the system becomes less; expresses concept of entropy
1st law of thermodynamics
aka conservation of energy; energy cannot be created or destroyed, but only converted from one form to another
kinetic energy
the energy of motion; can be used to do "work" i.e. bruised foot [owie]
potential energy
energy of position; has the capacity to do work i.e. book on desktop
A(n) _____ inhibitor binds to an area outside of the active site of an enzyme and impairs proper functioning of the enzyme.
Which of the following statements about ribozymes are true?

A. increase the rate of chemical reaction
B. do not shot high substrate specificity
C. are proteins
D. show high substrate specificity
A & D
What are competitive inhibitors?

A. bind to allosteric site on an enzyme and inhibit the enzyme's functioning
B. bind to the substrate and prevent it from interacting with the enzyme
C. bind to the active site of an enzyme and prevent substrates from binding.
The ____ site of an enzyme is where a molecule can bind non-covalently and affect the function of the active site of an enzyme.
What molecule is a common energy source for living organisms?

A. Heat
B. Adenosine triphosphate
D. Inorganic phosphate
B & C
When does feedback inhibition occur?

A. When an end product of a metabolic pathway inhibits the activity of an enzyme in the pathway and, thus, stops accumulation of more product.
B. When an end product of a metabolic pathway binds to the active site of an enzyme and prevents its proper functioning in a pathway.
Increasing the temperature outside the optimal range for an enzyme can lead to ____ of the enzyme, altering the enzyme's structure and function.
Which of the following occurs during the reduction of an atom or molecule?

A. the net charge of the atom or molecule decreases due to the addition of (a) negatively charged election(s).
B. the net charge of the atom or molecule increases due to the addition of (a) negatively charged electron(s).
C. one or more electrons are removed from the atom or molecule
D. one or more electrons are added to the atom or molecule
A & D
TRUE or FALSE: The energy needed to make ATP comes from catabolic reactions that are exergonic.
TRUE or FALSE: ATP synthesis is an exergonic reaction.
What are the steps in the ATP cycle?

A. Transfer of energy from ATP to another molecule, for example NADH
B. Breakdown of ATP using a water molecule to release energy
C. Synthesis of ATP using energy released from catabolic reactions
B & C
Vmax is the ____ rate of a chemical reaction.
The two main functions of catabolic pathways are to recycle components of ____ and to obtain _____ that can be used to drive endergonic processes.
Metabolic pathways can be regulated at the genetic, cellular, and biochemical levels. Which regulatory mechanisms target the rate of the reaction without changing the amount of enzyme the cell produces?
Metabolism includes which of the following?

A. Only the breakdown of organic molecules
B. Only the synthesis of organic molecules
C. Both the synthesis and breakdown of organic molecules
_____ are a type of catalyst that acts to speed up chemical reactions.
What do organic molecules provide?

A. Building blocks
B. chemical bonds to store energy
C. cellular processes
D. chemical reactions
A & B
TRUE or FALSE: Activation energy is needed for molecules to achieve the transition state.
How do competitive and noncompetitive inhibitors differ in their effects on enzyme function?

A. Competitive inhibitors bind to the active site or and enzyme and noncompetitive inhibitors bind to an allosteric site.
B. Only the effects of noncompetitive inhibitors can be overcome by increasing substrate concentration
C. Only the effects of competitive inhibitors can be overcome by increase substrate concentration.
D. Competitive inhibitors interfere with proper enzyme functioning while noncompetitive inhibitors do not.
A & C
Why are catalysts needed to increase the rate of a chemical reaction?

A. Chemical reactions require the input of energy, which is provided by catalysts
B. Catalysts add heat to speed up a reaction
C. Molecules must be in the proper orientation for bonds to form or be broken, which is aided by catalysts.
Once the ____ ____ has been achieved, a chemical reaction can proceed and products can be formed.
transition state
What is, in general, a barrier to the formation of products during a chemical reaction?

A. Heat must be added.
B. Activation energy is required for molecules to reach the transition state and product formation to proceed
C. All chemical reactions require enzymes for molecules to reach the transition state.
At what levels are metabolic pathways regulated?

Population, Genetic, Biochemical, Individual, Atomic, Cellular
Genetic, Biochemical, Cellular
Cells can control chemical pathways through ___ ____ because all metabolic pathways involve enzymes that are encoded by genes.
gene regulation
Why do most enzymes function maximally in a narrow range of temperature and pH?

A. Enzymes only function at a narrow range of conditions in which their substrates are available.
B. Enzymes evolved to function best at body temperature, with an optimum temperature of 37 degrees C
C. Exposing enzymes to temperatures and pH outside the optimal range can change the conformation of the active site or denature the protein.
Pepsin is an enzyme found in the stomach that functions best at an acidic pH. Why does pepsin not function well at a pH of 7?

A. All enzymes function best in acidic environments and poorly at neutral pH
B. Enzymes are sensitive to pH and function best across a narrow range of pH
How can the functioning of an enzyme be affected by the external environment?

A. Only increasing temperature can cause an enzyme to become denatured and no long function properly
B. Factors such as temperature, pH, and ionic conditions do not usually affect the function of enzymes
C. Altering the pH can be harmful to an enzyme when the pH is outside the normal or optimal range for that enzyme
D. Increasing the temperature can greatly affect the functioning of some enzymes by causing denaturation
C & D
What molecules are synthesized by cells for the purpose of storing energy that can later be used to drive chemical reactions?

ATP, NADH, glucose, pyruvate, ADP
____ energy is the initial input of energy needed to overcome repulsion between molecules in a chemical reaction.
What occurs during the process of autophagy in cells?

A. Intracellular materials are digested by the lysosomes
B. Intracellular materials are digested by proteasomes
What is an allosteric site?

A. A site on an enzyme where substrates bind.
B. A site on an enzyme where competitive inhibitors bind
C. A site outside of the active site of an enzyme.
List the following steps in the order they occur in an enzyme-catalyzed reaction.
Substrates bind to the enzyme at the active site
The enzyme undergoes conformational change to bind substrate tightly
Substrate is converted to products
Products are released from the enzyme
The enzyme is reused
What are the two general functions of catabolic pathways?

A. To convert matter into energy
B. To break down old macromolecules and recycle the components for use in the synthesis of new macromolecules
C. To synthesize new macromolecules that may be needed in cells
D. To obtain energy for use in endergonic processes
B & D
TRUE or FALSE: Thermodynamics is the study of energy changes in the Universe.
Some catalysts are pieces of RNA called ______.