Chapter 8: An Intro to Metabolism Flashcards
Although it is not an enzyme, hemoglobin shows cooperativity in binding O2. Use O2
binding in fish hemoglobin to explain cooperativity.
Hemoglobin is made up of four subunits, each of which has an oxygen-binding site. The binding of an oxygen molecule to one binding site increases the affinity for oxygen of the remaining binding sites. Thus, where oxygen is at high levels, such as in the gills, hemoglobin’s affinity for oxygen increases as more binding sites are filled.
a. What is the substrate molecule that initiates this metabolic pathway?
b. What is the inhibitor molecule
c. What type of inhibitor is it?
d. When does it have the most significant regulatory effect?
e. What is this type of metabolic control called?
a. Threonine
b. Isoleucine
c. Noncompetitive inhibitor
d. When it binds to an allosteric site
e. Feedback inhibition
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ____________ is to ____________.
a. exergonic; spontaneous
b. exergonic; endergonic
c. free energy; entropy
d. work; energy
b. exergonic; endergonic
Most cells cannot harness heat to perform work because
a. heat does not involve a transfer of energy.
b. cells do not have much thermal energy; they are relatively cool.
c. temperature is usually uniform throughout a cell.
d. heat can never be used to do work.
c. temperature is usually uniform throughout a cell.
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to…
a. add more of the enzyme.
b. heat the solution to 90 degrees C.
c. add more substrate.
d. add a noncompetitive inhibitor.
a. add more of the enzyme.
Some bacteria are metabolically active in hot springs because…
a. they are able to maintain a lower internal temperature.
b.high temperatures make catalysis unnecessary.
c. their enzymes have high optimal temperatures.
d. their enzymes are completely insensitive to temperature.
c. their enzymes have high optimal temperatures.
If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?
a. Additional substrate will be formed.
b. The reaction will change from endergonic to exergonic.
c. The free energy of the system will change.
d. Nothing; the reaction will stay at equilibrium.
d. Nothing; the reaction will stay at equilibrium.
Cooperativity
A kind of allosteric activation, when a substrate molecule binding to one active site in a multi-subunit enzyme triggers a shape change in all the subunits, thereby increasing catalytic activity at the other active sites.
