Podcast
Questions and Answers
Which of these statements about enzymes is true? (Select all that apply)
Which of these statements about enzymes is true? (Select all that apply)
- Most proteins are enzymes.
- Most enzymes are proteins. (correct)
- Enzymes are changed by the reactions they catalyze.
- The active sites of enzymes have little specificity for substrates.
Which of these statements about enzyme-catalyzed reactions is true? (Select all that apply)
Which of these statements about enzyme-catalyzed reactions is true? (Select all that apply)
- The rate of reaction is independent of temperature.
- The rate of all enzyme-catalyzed reactions is decreased when the pH is lowered from 7 to 2.
- The rate of reaction is independent of substrate concentration.
- Under given conditions of substrate concentration, pH, and temperature, the rate of product formation varies directly with enzyme concentration up to a maximum, at which point the rate cannot be increased further. (correct)
Which of these statements about lactate dehydrogenase is true? (Select all that apply)
Which of these statements about lactate dehydrogenase is true? (Select all that apply)
- It is a protein. (correct)
- It reduces another molecule (pyruvic acid). (correct)
- It oxidizes the lactic acid. (correct)
In a metabolic pathway, what happens to the product of one enzyme?
In a metabolic pathway, what happens to the product of one enzyme?
What is an inborn error of metabolism?
What is an inborn error of metabolism?
Which of these represents an endergonic reaction? (Select all that apply)
Which of these represents an endergonic reaction? (Select all that apply)
Which of these statements about ATP is true? (Select all that apply)
Which of these statements about ATP is true? (Select all that apply)
When oxygen is combined with 2 hydrogens to make water, what happens?
When oxygen is combined with 2 hydrogens to make water, what happens?
How do enzymes increase the rate of chemical reactions?
How do enzymes increase the rate of chemical reactions?
According to the law of mass action, which conditions will drive the reaction A + B to the right?
According to the law of mass action, which conditions will drive the reaction A + B to the right?
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Study Notes
Enzymes
- Most enzymes are proteins, highlighting their primary composition within biological reactions.
- Enzymes are not changed permanently by the reactions they catalyze, preserving their function for multiple reactions.
- Active sites of enzymes are specific for their substrates, facilitating selective binding.
Enzyme-Catalyzed Reactions
- Reaction rates depend on substrate concentration, pH, and temperature; they increase with enzyme concentration up to a maximum.
- Lowering pH from neutral (7) to acidic (2) typically decreases the rate of enzyme-catalyzed reactions.
Lactate Dehydrogenase
- Lactate dehydrogenase is a multifunctional protein that oxidizes lactic acid and reduces pyruvic acid, emphasizing its role in metabolic processes.
Metabolic Pathways
- In a metabolic pathway, the product of one enzyme is the substrate for the next, creating a sequence of biochemical transformations.
Inborn Errors of Metabolism
- Genetic changes can lead to defective enzymes, causing the accumulation of intermediates prior to the defective step and utilizing alternative pathways to manage these substrates.
Endergonic Reactions
- Endergonic reactions require energy input; examples include the synthesis of ATP from ADP and Pi and the photosynthesis of glucose from CO2 and H2O.
ATP (Adenosine Triphosphate)
- ATP is considered the "universal energy carrier" in cells, providing energy for various cellular activities.
- The high-energy bond between ADP and the third phosphate facilitates energy transfer during metabolic reactions.
- ATP production is coupled with energy-liberating processes, ensuring a balance between energy consumption and generation.
Redox Reactions
- Combining oxygen with two hydrogen atoms to form water involves the reduction of oxygen, while the hydrogen-donating molecule undergoes oxidation.
Activation Energy
- Enzymes enhance the rate of chemical reactions by lowering the activation energy required for reactants, making reactions occur more readily.
Law of Mass Action
- According to the law of mass action, driving a reaction to the right can be achieved by increasing the concentrations of reactants A and B while decreasing the concentration of product C.
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