Chapter 8 Flashcards
1
Q
First law of Thermodynamics
A
Energy is neither created or destroyed
2
Q
Second Law of Thermodynamics
A
Heat always moves from hotter objects to colder objects. “cold” is not energy and therefore cannot move
When energy is converted from one form to another, some of that energy becomes unavailable to do work, no energy transformation is 100%
3
Q
Potential energy
A
Energy of an object based on its position
4
Q
Kinetic energy
A
Energy of an object in motion
5
Q
endergonic
A
delta G is positive, reaction requires energy
6
Q
exergonic
A
delta G is negative, reaction releases energy
7
Q
Free energy
A
useful energy, associated with a reaction, that can perform work
8
Q
entropy
A
measure of the disorder in a system
9
Q
metabolism
A
Sum total of all chemical reactions in an organism
10
Q
anabolism
A
Complex molecules are made from simple molecules; energy input is required
11
Q
catabolism
A
a pathway that breaks down molecules into smaller subunits, energy is released
12
Q
metabolic pathway
A
The organization of all chemical reactions in a cell
13
Q
catalyst
A
-speed up the rate of reactions
-is not altered by the reactions
-most are enzymes
-RNA can also be a catalyst (ribosomes)
14
Q
energy of activation
A
amount of energy required to initiate a chemical reaction
15
Q
enzyme
A
-Biological catalyst
-lower the energy barrier for reactions
16
Q
Competitive inhibitor
A
Compete with the natural substrates for binding sites
17
Q
non-competitive inhibitor
A
Bind to the enzyme at a different site (not the active site)
18
Q
reversible inhibitor
A
Inhibitor bonds non-covalently to the active site and prevents substrate from binding.
19
Q
non-reversible inhibitor
A
Inhibitor covalently bonds to side chains in the active site-permanently inactivates the enzyme
20
Q
allosteric regulation
A
natural, noncompetitive, reversible inhibitors and/or activators of enzyme activity
21
Q
active site
A
where substrate molecules bind to the active site of the enzyme
22
Q
transition state
A
activation energy changes the reactants into unstable forms with higher free energy (transition state intermediates)
23
Q
coenzyme
A
(enzyme helpers) electron taxis that transfer electrons from one reaction to another
24
Q
cofactor
A
Inorganic ions bound to enzyme
25
prosthetic group
non-amino acid organic groups bound to enzymes
26
reactants (substrates)
substrates, what binds to enzyme
27
intermediates
compounds that are between steps of important pathways
28
end products
the final products of a reaction
29
oxidizing agent
what does the oxidizing, it is reduced (has an extra electron)
30
reducing agent
What does the reducing, it is oxidized (loses an electron)
31
oxidized
OIL RIG oxidized and has one less electron
32
reduced
OIL RIG reduced gains an extra electron
33
Which statements describe a chemical reaction?
A solid melts to a liquid.
Atoms are rearranged, but do not change.
A gas is formed when two substances mix.
A salt such as NaCl dissolves in water
-Atoms are rearranged but do not change
-A gas is formed when two substances mix
34
Which of the statements regarding potential energy is true?
Potential energy cannot be stored and is immediately converted to kinetic energy.
Potential energy is the energy that an object has based on its position.
An object in motion does not have any potential energy.
The potential energy of an object cannot be determined.
Potential energy is the energy that an object has based on its position
35
Which of these describes a catabolic pathway?
a pathway that transmits a signal within a cell
a pathway that constructs molecules from smaller subunits
a pathway that consumes energy
a pathway that breaks down molecules into smaller subunits
a pathway that breaks down molecules into smaller subunits
36
How do organisms use energy, according to the first law of thermodynamics?
All organisms break down molecules to convert chemical energy into kinetic energy.
Plants are more energy efficient than animals because plants trap heat from the sun.
Heterotrophic organisms, or consumers, create energy using the food they consume.
Animal movement produces heat, which is the form energy takes when it is destroyed.
The light energy collected during photosynthesis is converted to chemical energy.
All organisms break down molecules to convert chemical energy into kinetic energy
The light energy collected during photosynthesis is converted to chemical energy
37
What does the second law of thermodynamics state about energy?
When a warm object loses thermal energy to a colder object, all the energy from the warm object is transferred to the colder object.
As heat disperses into a colder object, coldness disperses into the heat source until their temperatures are equal.
When energy transforms, the energy breaks down from a neatly organized state to a state of disarray.
Given the opportunity, energy disperses away from a concentrated source into places with less energy.
Given the opportunity, energy disperses away form a concentrated source into places with less energy
38
Which definition describes enthalpy?
a difference in the charge that drives the movement of ions across a membrane
a measure of the amount of internal energy in a system at constant pressure
a measure of the amount of disorder present in a given system
the spatial arrangement of the atoms and chemical bonds that hold a molecule together
a measure of the amount of internal energy in a system at constant pressure
39
Which statement best describes free energy?
a measure of how fast a reaction can take place
energy that must be added for a reaction to be spontaneous
energy that is added to start a reaction
useful energy, associated with a reaction, that can perform work
the amount of energy wasted in a chemical reaction
useful energy, associated with a reaction, that can perform work
40
Which molecule is used as the primary source of chemical energy for tasks within a cell?
glucose
NADH
phospholipids
ATP
ATP
41
How does adenosine triphosphate (ATP) drive energy‑required reactions in the cell?
The hydrolysis of ATP releases heat to drive energy‑requiring reactions.
The hydrolysis of ATP is coupled to a non‑spontaneous reaction.
ATP generates a proton gradient to drive reactions.
ATP increases the activation energy of a reaction.
ATP allows metabolic reactions to proceed without an enzyme.
the hydrolysis of ATP is coupled to a non-spontaneous reaction
42
Which statement is an example of the chemical potential energy in adenosine triphosphate (ATP) being turned into work?
ATP is spontaneously hydrolyzed to ADP.
ATP is bound by an enzyme but is not hydrolyzed.
A phosphate group is transferred from ATP to glucose during glycolysis.
ATP synthase transfers a phosphate to ADP.
After splitting ATP, a protein changes shape to pump ions across a membrane.
A phosphate group is transferred from ATP to glucose during glycolysis
After splitting ATP a protein changes shape to pump ions across a membrane
43
Which of the statements describe a catalyst?
decreases the energy difference between reactants and products
is not consumed during the chemical reaction
increases the rate of endergonic reactions
is a protein that functions in a metabolic reaction
lowers the activation energy of a chemical reaction
is not consumed during chemical reaction
increases the rate of endergonic reactions
lowers the activation energy of chemical reaction
44
Which of the statements best describes the overall role of enzymes in metabolism?
Enzymes decrease the speed of reactions.
Enzymes only break down large molecules.
Enzymes increase the speed of reactions.
Enzymes prevent reactions from requiring ATP.
Enzymes increase the speed of reactions
45
Choose the best definition for activation energy.
energy difference between reactants and products in a reaction
energy absorbed during a chemical reaction
energy that is stored in chemical bonds
energy produced by the movement of an atom
amount of energy required to initiate a chemical reaction
amount of energy required to initiate a chemical reaction
46
Q
What is the significance of a lower activation energy?
It increases overall cellular energy expenditure.
It slows the rate at which products are formed.
It increases the rate of a cellular reaction.
It increases the rate at which enzymes are consumed
It increases the rate of a cellular reaction
47
Which of the choices are examples of coupled reactions?
In water, sodium choloride (NaCl) dissociates into sodium and chloride ions.
ATP hydrolysis drives lactose synthesis from glucose and galactose.
ATP is hydrolyzed by water without the presence of enzymes.
ATP synthesis is driven by a proton gradient formed in the mitochondria.
Sucrose hydrolysis by water results in glucose and fructose.
ATP hydrolysis drives lactose synthesis from glucose and galactose
ATP synthesis is driven by a proton gradient formed in the mitochondria
48
How do enzymes recognize their substrates?
a binding site that complements the charge of the substrate
a binding site that fits the shape and complements the charge of the substrate
a binding site that fits the shape of the enzymatic product
an unstructured, negatively charged tail that recruits the substrate to the enzyme
A binding site that fits the shape and complements the charge of the substrate
49
How do enzymes lower the activation energy of a reaction?
by stressing a bond in a substrate that needs to be broken
by forming a temporary bond between the active site and the substrate
by using product molecules in the allosteric site to disable the active site
by producing conditions within the active site conducive to the reaction
By stressing a bond in a substrate that needs to be broken
by forming a temporary bond between the active site and the substrate
by producing conditions within the active site conducive to the reaction
50
How do enzymes affect the activation energy of a reaction?
Enzymes lower the activation energy of a reaction
51
Which describes how cofactors and coenzymes affect the function of enzymes?
increase or decrease catalytic function
do not impact catalytic function
increase catalytic function
decrease catalytic function
increase catalytic function
52
Where should the drug bind to allosterically inhibit the enzyme?
to the substrate of the enzyme
to a site on the enzyme other than the active site
to the active site of the enzyme
to the mRNA that encodes the enzyme
to a site on the enzyme other than the active site
53
Penicillin is an enzyme‑inhibiting antibiotic that kills bacteria by suppressing the synthesis of bacterial cell walls. The bacterial cell wall is made of cross‑linked peptidoglycan, which is synthesized from peptidoglycan monomers by transpeptidase enzymes. How does penicillin suppress the synthesis of bacterial cell walls?
Penicillin binds to the cross‑linked peptidoglycan, preventing further bacterial cell wall growth.
Penicillin binds to the peptidoglycan monomers, preventing their conversion to cross‑linked peptidoglycan.
Penicillin binds to the transpeptidase enzymes, preventing the synthesis of cross‑linked peptidoglycan.
Penicillin signals the bacterial cell to stop producing the transpeptidase enzymes.
Penicillin binds to the transpeptidase enzymes, preventing the synthesis of cross-linked peptidoglycan
54
Feedback inhibition is important for the regulation of many metabolic pathways. Which of the statements are examples of feedback inhibition?
An intermediate of glycolysis activates an enzyme downstream in the pathway.
Arsenic binds to pyruvate dehydrogenase and inhibits the enzyme.
The beginning of glycolysis is inhibited by high levels of ATP in the cell.
The production of isoleucine is halted by the presence of excess isoleucine.
The lac operon is not transcribed when there is no lactose present.
The beginning of glycolysis is inhibited by high levels of ATP in the cell
the production of isoleucine is halted by the presence of excess isoleucine
55
The reaction rate slows because the temperature affects the function of the enzyme. Keeping in mind that enzymes are proteins, pick the best reason why enzyme function declines above a certain temperature.
Enzyme inhibitors are more active at higher temperatures.
Enzyme structure is distorted by heat, and it cannot bind substrate.
The hydrogen bonds between nucleotides are broken by heat.
The primary structure of the enzyme is disrupted by heat.
Enzyme structure is distorted by heat and it cannot bind substrate
