Energy and Enzymes Reading Guide Flashcards
Define metabolism.
all of the chemical reactions that take place inside of cells that use and release energy
How are catabolic pathways and anabolic pathways different? Give an example of each.
Catabolic pathways: break down complex molecules (breakdown of sugars to a single glucose molecule)
Anabolic pathways: require an input of energy to synthesize complex molecules from simpler ones (synthesizing sugar from CO2)
What is kinetic energy?
energy with objects in motion
What is potential energy?
the potential to do work
What is chemical energy?
potential energy that exists within chemical bonds that releases when those bonds are broken
What is Gibb’s free energy (G)?
Usable energy, or energy that is available to do work.
What is the equation for the change in free energy (ΔG)?
𝛥G=𝛥H−T𝛥S
What is enthalpy?
measure of heat transferred/measure of energy in a system
What is entropy?
measure of randomness or disorder in a system
Explain how free energy can change (ΔG) as a function of temperature.
An increase or decrease in temperature affects the entropy value which can cause the change in G to go above zero or stay below zero which affects spontaneity
What does it mean for chemical reactions if ΔG is positive (greater than zero)?
Positive ΔG means the reaction is endothermic, endergonic, and nonspontaneous.
What does it mean for chemical reactions if ΔG is negative (less than zero)?
Negative ΔG means the reaction is exothermic, exergonic, and spontaneous.
Contrast endergonic and exergonic reactions and give an example of each.
Endergonic absorbs energy, exergonic releases energy.
Endergonic example: Synthesis of glucose builds complex molecules like sugars from simpler molecules requires energy.
Exergonic example: The breakdown of sugar into simpler molecules releases energy.
Describe what it means for a chemical reaction to be at equilibrium.
Rate of the forward reaction is equal to the rate of the reverse reaction, no net change in concentrations of reactants and products.
Describe the structure of ATP (adenosine triphosphate). How is it different from ADP (adenosine diphosphate) and Pi (inorganic phosphate)?
ATP: adenosine bound to three phosphate groups, nitrogenous base adenine and a five-carbon sugar called ribose (higher energy than ADP because of the additional phosphate group)
ADP: adenosine bound to two phosphate groups
Pi is a byproduct of energy released when ATP is used
How does the ATP hydrolysis reaction release energy?
Breaks high energy bonds between phosphate groups in the ATP molecule, and converts it to ADP and a phosphate group.
How do cells use the energy released from ATP hydrolysis to power endergonic reactions via energy coupling?
A phosphate group is transferred from ATP to the reactant molecule of the endergonic reaction that provides energy to drive the reaction forward.
What is an enzyme?
Special molecules that catalyze biochemical reactions
Why does free energy increase to reach the transition state?
The transition state is highly unstable, and an input of energy is required to achieve a state where bonds are partially broken and partially formed
How do enzymes speed up chemical reactions?
Enzymes speed up chemical reactions by binding to reactant molecules and holding them to make the chemical bond-breaking and forming processes take place more readily.
Explain how enzymes interact with specific substrates at the enzyme’s active site.
The active site is a region on the enzyme where the substrate binds and it is specifically designed to bind a specific substrate, allowing the enzyme to catalyze a chemical reaction by bringing the substrate molecules together at a specific orientation for the reaction to happen.
How do changes in temperature and pH affect an enzyme’s activity?
High temperatures can cause an enzyme to denature which changes its natural properties. Enzymes only function at a specific pH or pH range, so they can denature at extreme pH values.
Explain how enzymes interact with substrates via the induced fit model.
Enzymes and substrates come together and their interaction causes a shift in the enzyme structure that confirms the ideal binding arrangement between the enzyme and the substrate’s transition state. This maximizes the enzyme’s ability to catalyze the reaction.
How are enzymes regulated via competitive inhibition?
An inhibitor molecule competes with substrate for active site binding
