Ch. 8 An Introduction To Metabolism Flashcards
What is Metabolism?
The totality of an organism’s chemical reactions
What is energy?
The capacity to cause change
Free energy
Energy available to do work in a living system when temperature and pressure are uniform
Free energy change = 🔼 G (this is how it’s abbreviated)
What is kinetic energy
Energy associated w/ motion
Heat (aka thermal energy)
Is kinetic energy associated w/ random movement of atoms or molecules
Potential energy
Energy that matter possesses b/c of it’s location or structure
What is this an example of?
The contraction of leg muscles pushes bicycle pedals
Kinetic energy
What is this an example of?
Water behind a dam, for instance possesses energy b/c of the altitude above sea level
Potential energy
What type of energy is contained in chemical bonds in a molecule?
Chemical energy
What are the characteristics of an endergonic reaction?
Absorbs free energy from it’s surroundings; essentially stores free energy in molecules so
🔼G is positive
What are the characteristics is exergonic reaction
Proceeds w/ a net release of free energy; b/c the chemical mixture loses free energy 🔼 G is negative
What are the characteristics of an anabolic reaction?
It links simple molecules to form complex ones (endergonic)
What are the characteristics of catabolic reaction?
Breaks down complex molecules into simpler ones ( exergonic)
What is energy coupling
The use of an exergonic process to drive an endergonic one; most energy coupling in cells is mediated by ATP
What is the general structure of ATP?
3 phosphate groups, sugar ribose, and the nitrogenous base adenine
What type of charge do the phosphate groups possess?
Negative charge
ATP has 3 phosphate groups. Which phosphate group is broken off to release energy?
Terminal phosphate bond / Triphosphate group
Which phosphate groups is added to re-build ATP?
Inorganic phosphate + ADP + energy = ATP
Why does it take so much energy to build ATP/ Why does it release so much energy? (hint: electrical charges of the phosphate groups)
The phosphate groups have a strong negatively charged
Hydrolysis breaks down ATP: Is the breakdown of ATP endergonic or exergonic?
Exergonic
Hydrolysis breaks down ATP: Is the synthesis (re-building) of ATP endergonic or exergonic?
Endergonic
What is the energy given off by the ATP used for?
To perform three types of cellular work: chemical, transport, and mechanical
Where does the energy to rebuild ATP come from? (Be specific!)
The energy released by breakdown reactions (catabolism) in the cell is used to phosphorylate (add inorganic phosphate to) ADP, regenerating ATP
What is a catalyst?
A chemical agent that speeds up a reaction without being consumed by the reaction
What type of molecule are most enzymes?
Protein molecules (macromolecule)
How do enzymes work?
They speed up reactions without adding heat
How do enzymes affect the energy of activation?
They reduce the activation energy
Do enzymes affect the change in free energy (ΔG) of a reaction?
No, ΔG is unaffected by the enzyme
What is the same and what is the difference btw the progress of reactions with or without an enzyme?
Same: Free energy
Different: course of reaction and activation energy
How does the active site of an enzyme lower an EA barrier? Explain.
Enzyme can converts one or two reactant molecules to one or more product molecules
Substrate
The reactant on which an enzyme works
Active site
The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs (the puzzle piece slot that substrate goes inside of)
Transition state
When the molecules have absorbed enough energy for the bonds to break and the reactants are in this unstable condition
Enzyme-substrate complex
A temporary complex formed when an enzyme binds to it’s substrate molecule(s)
Induced fit
Caused by the entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate
What is the function of cofactors and coenzymes?
A coenzyme is just an organic molecule serving as a cofactor which is any nonprotein molecule or ion that is required for the proper functioning of an enzyme
Can be permanently bound to active site or bind loosely and reversible, along with substrate, during catalysis
What environmental conditions affect enzyme activity?
Temperature and pH
Why do enzymes susceptible (harmed) to denaturation? (what kind of molecules are they?)
Each enzyme has an optimal temperature and pH that favor the most active shape of the protein molecule
What is a metabolic pathway?
Each step is catalyzed by a specific enzyme, it begins with a specific molecule and ends with a product
Why is the role of enzymes important in a metabolic pathway?
A cell can regulate metabolic pathways by controlling the enzyme concentration in the cell
What are enzyme inhibitors?
Certain chemicals selectively inhibit the action of specific enzymes
Competitive inhibitors
Bind to the active site of an enzyme, competing with the substrate
Noncompetitive inhibitors
Bind to a different part of an enzyme, causing the enzyme to change shape and making the active site less effective (aka allosteric control)
What examples of enzyme inhibitors?
Toxins, poisons, pesticides, and antibiotics
How does feedback inhibition work? Explain.
A metabolic pathway is halted by the inhibitory binding of it’s end product to an enzyme that acts early in the pathway.
