AP Bio - Unit 3 Cellular Energetics
What identifies the source of matter used by photosynthetic organisms to form carbohydrates?
Carbon Dioxide
Define endergonic reactions
Non spontaneous (G>0) and require energy. (spontaneous = energy released not instantaneous)
Compare potential energy and kinetic energy
kinetic = energy of motion potential = stored energy
Describe why the molecular formula of ATP is unstable and highly energetic
the three phosphates are negative and they repel each other (unstable bond)
State the first law of thermodynamics
the universe contains a constant amount of energy.
Where does the electron transport chain occur in photosynthesis and cellular respiration respectively?
thylakoid membrane: mitochondrial cristae
State another name for the first law, and define it in reference to change, or new energy.
the law of conservation of energy. Energy is converted from one form to another. Example" Kinetic --> Potential; Potential --> Kinetic
In an icredible process, water is split (breaking a strong polar covalent bond) in order to replace electrons during:
the light reactions
Identify the product of CO2 + H2O <--> H2CO3
H2CO3
Identify the molecule formed when ATP loses a phosphate
ADP
Identify the products of ATP + H2O ---> ADP + Pi
ADP and Pi
Identify the reactants of CO2 + H2O <--> H2CO3
CO2 and H2O
Identify the type of reaction for ATP + H2O ---> ADP + Pi
Hydrolysis
Describe why the phrase "universal currency of cellular energy" is used to describe ATP
It provides energy in a form that nearly all cells can use to perform work.
what aspect of the following energy forms qualifies them as being kinetic forms of energy? Light energy: Electricity: Thermal Energy:
Light energy: movement of photons Electricity: movement of electrons Thermal Energy: movement of particles generating heat.
Identify what changes in a chemical reaction
The bonds among atoms change as they form new molecules.
Define Metabolic Pathway
Series of chemical reactions in which molecules are broken down or built up.
State the second law of thermodynamics
The transformation of energy is associated with an encrease in disorder of the universe
Use the chemistry of bonding to describe the organic molecules (Carbohydrates, Lipids, and proteins) are called fuel molecules
They have weak covalent bonds, which means they have rich chemical energy which is why they are considered to be fuel.
Redox reactions involve a transfer of electrons where on molecule loses electrons as another gains electrons. In photosynthesis which reactant is oxidized?
Water
Describe how ATP provides energy to other reactions
bonds between phosphate groups are unstable and high energy, so they release a lot of energy when broken.
Justify how cells can continue to organize without violating the second law of thermodynamics, which states that systems tend toward chaos.
cells can use energy , they don't exist in isolation and can harness energy from other molecules.
Construct the formula for Gibbs free energy and describe the equation in words.
delta G = G products - G reactants
Identify three types of potential energy
gravitational chemical ball at the top of the stairs example
Identify the primary entropy increase in chemical reactions
heat (thermal energy)
Identify three cellular actions fueled by ATP.
muscle contraction cell movement membrane pumps
Define energetic coupling
process in which a spontaneous reaction drives a nonspontaneous reaction
State what the reversable arrow means in CO2 + H2O <--> H2CO3
reaction can go either way
Define exergonic reactions
reactions are spontaneous (G < 0) and release energy.
Noncompetitive inhibitors bind to the:
Allosteric Site
The building blocks of enzymes are:
Amino Acids
Identify the molecule formed when ATP loses two phosphates
AMP
Identify the reactants of ATP + H2O ---> ADP + Pi
ATP and H2O
Justify the statement, "The weaker the covalent bond, the more chemical energy the molecule contains"
ATP has a weak bond which means the molecule is an unstable molecule which needs high chemical energy
Justify the following statement. "the use of ATP as a ready, accessible form of chemical energy in nearly all cells reflects its use in cells that evolved early in Earth's long history"
ATP is used by all cells to power them.
ATP Synthase is an essential enzyme that utilizes the flow of hydrogen ions in order to catalyze the phosphorylation of ADP to ATP. This process produces the most ATP of any process in the human body. Without this enzyme, humans would produce ATP only through anaerobic respiration and would not produce enough to survive Which of the following statements BEST describes how ATP synthase catalyzes the reaction of ADP phosphorylation?
ATP synthase decreases the activation energy.
The most important part of an enzyme's structure is the:
Active Site
Describe how the first law of thermodynamics applies to chemical reactions
Because energy is not created or destroyed in the first law, chemical reactions do not create or use up energy; they transfer energy between different types of molecules and the environment.
Explain why a metabolic pathway typically proceeds quickly to the right.
Because the products are quickly used again. the direction is influenced by the concentration of reactants and products
Identify three organic molecules that are rich sources of chemical energy
Carbohydrates Lipids Proteins
Chymosin belongs to a class of enzymes referred to as proteases. Caseins (proteins found in milk) are emulsifiers that bind the fat and water in milk and keep the milk from separating into parts. Chymosin is able to hydrolyze casein; the result of this reaction curdled milk. What BEST describes the mechanism for the interaction of chymosin and casein?
Casein is the substrate, and it binds to the active site on the chymosin enzyme. Chymosin cleaves the casein in half, and this compromises casein's ability to bind the immiscible fat and water portions of milk; as a result, the milk curdles.
Chemical energy = kinetic energy + _________
Chemical energy = kinetic energy + thermal energy.
Enzymes are biological catalysts that work to speed up naturally-occurring processes in the body. The function of enzymes is essential to the survival of all living things. The graph below represents an energy diagram for the enzyme, DNA polymerase. DNA polymerase works to bind nucleotides together in order to form a new strand of DNA. A group of students is working to determine how DNA polymerase catalyzes its reaction by timing the number of strands of DNA that a particular enzyme can catalyze and observing the amount of energy of products and reactants, as exemplified above. Which of the following statements BEST describes how DNA polymerase speeds up the reaction of nucleotide binding and correctly identifies a potential constant for the experiment described?
DNA polymerase speeds up the reaction of nucleotide binding by decreasing the activation energy. A potential constant for the experiment is the sequence of DNA copied.
State the meaning of delta in a chemical reaction
Difference between 2 values.
Plants contain a variety of pigments capable of absorbing light. Why is this biologically beneficial.
Different pigments absorb varying wavelenghts of light, giving plants a broader range for light absorption.
Oxidative phosphorylation generates the most ATP for an anaerobically respiring cell. Wht two event occur during this process?
ETC and chemiosmosis
The electron transport chain (ETC), located in the inner membrane of mitochondria, powers cellular respiration. As a final step in the process, cytochrome c oxidase transfers electrons to oxygen to form water. Which of the following BEST predicts the outcome of an experiment where isolated mitochondria are treated with cyanide, an inhibitor of cytochrome c oxidase?
Electron carriers would remain reduced, cell damage and death would occur.
Describe spontaneous chemical reactions
Energy is released (not instantaneous)
Identify the energy transfer of this reaction
Exergonic = product have free energy
Have you ever noticed that when you clean your room, doesn't stay clean? A system tends to go toward _______ or _________. What does it take to keep a system --or your room -- in an organized and orderly stat? Adding ______ lowers the disorder, or increases the order, of a system.
Have you ever noticed that when you clean your room, doesn't stay clean? A system tends to go toward Disorderliness or High Entropy. What does it take to keep a system --or your room -- in an organized and orderly stat? Adding Energy lowers the disorder, or increases the order, of a system.
In a metabolic pathway, the _______ of one reaction is the _________ for the next. As ______ molecules with _____ chemical energy are broken down into ___________ , cells package the energy that is released into a ______________ that is accessible to the cell. The most common form is ____________________ , or ____________
In a metabolic pathway, the product of one reaction is the reactant for the next. As large molecules with lots of chemical energy are broken down into smaller ones, cells package the energy that is released into a chemical form that is accessible to the cell. The most common form is Adenosine Triphosphate, or ATP.
In muscle contraction, potential energy in the form of ______ is converted to _______. Much of the potential energy is dissipated as ________ which explains why as you exercise your muscles __________.
In muscle contraction, potential energy in the form of ATP is converted to Kinetic Energy. Much of the potential energy is dissipated as Thermal Energy which explains why as you exercise your muscles Warm.
State the relationship between exergonic reactions and Gibbs free energy.
Reactions with a negative delta G that release energy and proceed spontaneously are exergonic. so if the products of a reaction have less free energy that the reactants, delta G is negative and energy is released and available to do work.
State the relationship between endergonic reacions and Gibbs free energy.
Reactions with a positive delta G that require an input of energy and are not spontaneous are called endergonic so if the products of a reaction have more free energy than the reactants, delta G is positive and a net input of energy is required to drive the reaction forward.
Students disagree on whether or not photosynthesis occurs in organisms other than plants. what is the correct understanding of this.
Plants are not the only organism that can undergo photosynthesis. photosynthetic bacteria like cyanobacteria were among the first organisms to harves light energy to make organic molecules
Define Entropy
The energy that is not available to do work takes the form of an increase disorder.
What best descibes what happens when an enzyme get denatured?
The enzyme unfolds as secondary, tertiary, and quaternary structures become disrupted
The fixation of carbon dioxide occurs in the stroma and results in the synthesis of carbohydrates. which of the following observations supports this idea
The enzymes of the light - independent cycle are localized in the stroma.
Define Gibbs free energy
The free energy of the products minus the free energy of the reactants.
Define Chemical Reaction
The process by which reactants are transformed into products.
In the anscence of oxygen, plants will break down sugars into carbon dioxide and alcohols or acids. What best explains how this pathway likely arose?
To get the most out of phosphorylation per molecule of pyruvate without the ability to utilize respiraton.
define chemical energy
a form of potential energy held in the bonds of molecules
Describe the type of energy acquired from food
the food we eat contains chemical energy, a form of potential energy held in the chemical bonds between pairs of atoms in a molecule
where is the pH the lowest in a mitochondria during cellular respiration?
the intermembrane space
Biologically speaking, the purpose of fermentation is what?
to recycle NAD+ and FADH
If a great amount of H2CO3 is present in CO2 + H2O <--> H2CO3, in which direction will the reaction proceed?
to the left
Explain why carbon dioxide and water contain little chemical energy
when there's a strong bond like CO2, it needs very little chemical energy.
