Chapter 15 - Matabolism Basics Flashcards
What is meant by intermediary metabolism?
The highly integrated biochemical reactions that take place inside the cell.
What is anabolism?
the set of biochemical reactions that use energy to build new molecules and ultimately new cells.
What is catabolism?
the set of biochemical reactions that extract energy from fuel sources or break down biomolecules.
What are the three primary uses for cellular energy?
Cellular movements and the performance of mechanical work
active transport
biosynthetic reactions
What factors account for the high phosphoryl-transfer potential of nucleoside triphosphates?
Charge repulsion
resonance stabilization
increase in entropy
stabilization by hydration
Why does it make good sense to have a single nucleotide, ATP, function as the cellular energy currency?
Having only one nucleotide function as the energy currency of the cell enables the cell to monitor its energy status.
Metabolic pathways frequently contain reactions with positive standard free-energy values, yet the reactions still take place. How is it possible?
The free-energy changes of the individual steps in a pathway as summed to determine the overall free-energy change in the entire pathway. Consequently, a reaction with a positive free-energy value can be powered to take place if coupled to a sufficiently exergonic reaction.
What is the structural feature common to ATP, FAD, NAD+, and CoA?
an ADP unit
What are the activated electron carriers for catabolism?
NADH and FADH2
What are the activated electron carriers for anabolism?
NADPH
What are the three principal means of controlling metabolic reactions?
Control the amount of enzymes
control of enzyme activity
control the availability of substrates
Digestion is the first stage in the extraction of energy from food, but no useful energy is acquired in this stage. Why is digestion considered a stage in energy extraction?
Unless the ingested food is converted into molecules capable of being absorbed by the intestine, no energy can ever be extracted by the body.
The reaction of NADH with oxygen to produce NAD+ and H2O is very exergonic, yet the reaction of NADH and oxygen takes place very slowly.
Why does a thermodynamically favorable reaction not take place rapidly?
Although the reaction is thermodynamically favorable, the reactants are kinetically stable because of the large activation energy. Enzymes lower the activation energy so that the reaction takes place on time scales required by the cell.
