Chapter 6 Flashcards
Kinetic energy
Energy in motion
Potential energy
Stored energy
First Law of Thermodynamics
Energy cannot be created or destroyed. Energy can only change from one form to another (e.g., potential to kinetic)
Second Law of Thermodynamics
Energy cannot be transformed from one form to another with 100% efficiency
Entropy
measure of randomness or disorder of a system
Free energy
energy available to do work
Endergonic
products have more free energy than reactants.
In an endergonic reaction, ∆G is ________.
Positive
Exergonic
products have less free energy than reactants
In an exergonic reaction, ∆G is ______.
Negative
Activation energy
energy that must be processed by a molecule in order for it to undergo a chemical reaction
Catalysis
ATP is composed of three components:
- Ribose (5-carbon sugar)
- Adenine (composed of two carbon-nitrogen rings)
- Three phosphates
Synthesis of ATP from ADP + Pi is _______, which results in a _______ delta-G.
Endergonic; positive
Hydrolysis of ATP to ADP + Pi is ________, which results in a _______ delta-G.
Exergonic; negative
Substrate
molecule on which an enzyme acts
Active site
region of an enzyme surface to which a substrate binds
Enzyme-substrate complex
complex formed when an enzyme binds with its substrate
Multienzyme complex
assembly of several enzymes catalyzing different steps in a sequence of reactions
What is the optimum temperature of enzymes?
35-40°C
What is the optimum pH of enzymes?
pH 6-8
Inhibitor
substance that binds to an enzyme and decreases its activity
Competitive inhibitor
Competes with substrate for the same active site
Noncompetitive inhibitor
Binds to enzyme in a location other than the active site, changing the enzyme’s shape so it cannot bind the substrate
Allosteric site
part of an enzyme away from its active site
Allosteric activator
substance that binds to allosteric site to keep an enzyme in its active configuration
An allosteric activator _______ enzyme activity.
Increases
Metabolism
total of all chemical reactions carried out by an organism
Anabolism
chemical reaction that expends energy to build up molecules
Catabolism
chemical reaction that harvests energy by breaking down molecules
During a _______ reaction, complex molecules are broken down into simpler compounds.
Catabolic
Biochemical pathways
product of one reaction becomes the substrate of the next reaction
During _______ ________, end-product becomes allosteric inhibitor for the first enzyme in the biochemical pathway.
Feedback inhibition
Energy flows into ecosystems from the ______.
Sun
The most common way of measuring energy is as _____.
Heat
Redox reactions transfer ______ energy.
Potential
The reduced form of a molecule has ______ potential energy than the oxidized form.
Higher
When energy is converted to another form, some of it is lost as ______.
Heat
T or F: Order is more likely than disorder.
F: disorder is more likely than order
Order is ____ stable, and disorder is _____ stable.
Less; more
What are two ways the rate of reactions can be increased?
- Increasing energy of reacting molecules (e.g., heating up reactants)
- Lowering activation energy (e.g., catalysts)
T or F: Catalysts make endergonic reactions faster AND makes them spontaneous.
F: Catalysts make endergonic reactions faster BUT NOT spontaneous
How does carbonic anhydrase relate to homeostasis in the cell?
If blood becomes too acidic, certain reactions cannot happen. Carbonic anhydrase helps maintain level of pH of RBCs
Where do enzymes occur in a cell?
Cytoplasm and cell membranes/organelle membranes (e.g., mitochondria, nucleus)
What are 3 advantages of multienzyme complexes?
- Keeps next substrate in association with correct enzyme
- Limits unwanted side reactions
- Controlled as a unit
What affects rate of enzyme catalyzed reactions?
- Temperature
- pH
- Inhibitors and activators
The efficiency of biochemical pathways is coordinated/regulated by the cell. What is meant by efficiency?
- not making a product that is not needed
- not making energy when there is enough energy
- not wasting energy/chemical resources
An enzyme _____ activation energy.
Lowers
Increase in temperature of an uncatalyzed reactions _______ its rate.
Increases
What happens to an enzyme below the optimum temperature?
Enzyme’s shape is not flexible enough to permit induced fit (how well substrate fits inside active site)
What happens to an enzyme above the optimum temperature?
Forces are too weak to maintain enzyme’s shape; enzyme can denature
In Gibbs free energy, H =
Enthalpy, or the total energy in a molecule’s chemical bonds
In Gibbs free energy, TS =
Amount of disorder in the system
Gibbs free energy is symbolized by ______.
G
In an endergonic reaction, energy…
Must be supplied
In an endergonic reaction, energy…
Must be supplied
In an exergonic reaction, excess energy is
Released
In an exergonic reaction, excess energy is
Released
How does energy enter an ecosystem?
From the Sun
How do biological systems ‘locally’ work to decrease entropy?
By expending energy (ATP) constantly
How does ATP store energy?
By breaking bonds between P-groups (exergonic)
