Lecture 5 Flashcards
An organism gains energy using sugars as an electron donor and Fe+3 as an electron acceptor. This type of metabolism is an example of:
A) aerobic organotrophy
B) anaerobic lithotrophy
C) aerobic lithotrophy
D) anaerobic organotrophy
D) anaerobic organotrophy
When organic molecules, such as sugars, are the electron donor in energy-yielding reactions, the process is known as ?
organotrophy
Which reaction pairs both have positive free energy changes?
A) ATP hydrolysis and reduction of NAD+
B) ATP hydrolysis and oxidation of NADH
C) ATP production and oxidation of NADH
D) ATP production and reduction of NAD+
D) ATP production and reduction of NAD+
Since ATP hydrolysis and NADH oxidation liberate energy, ATP production and NAD+ reduction to form NADH require energy. Energy-requiring reactions have positive ΔG values.
What is it called when inorganic food molecules serve as electron donors in energy-yielding metabolic reactions?
A) lithotrophy
B) organotrophy
C) phototrophy
D) fermentation
lithotrophy
Organisms can obtain energy from light (phototrophy) or from the chemical bonds of molecules (chemotrophy).
Chemotrophy is divided into ____ (organic molecules serve as the energy source) and ____ (inorganic molecules serve as the energy source).
Organotrophy; Lithotrophy
What role do enzymes perform in allowing for chemical reactions to occur at a quicker rate?
They decrease activation energies
Which of the following molecules can donate electrons in metabolic reactions?
A) ADP
B) ATP
C) NAD+
D) NADH
NADH
ATP production and hydrolysis are not redox reactions. NADH is the reduced form of NAD+ and can donate electrons to other molecules in redox reactions.
Before feeding into the TCA cycle, pyruvate is first converted to ?
A) FADH2
B) citrate
C) acetyl-CoA
D) NADH
C) acetyl-CoA
After glycolysis, pyruvate has two potential fates. If no electron acceptor is available to perform respiration, pyruvate enters the fermentation pathway. If respiration can occur, pyruvate is first acted on by the pyruvate dehydrogenase complex; one product is acetyl-CoA.
As electrons are passed down an electron transport system…
A) NADH is produced
B) Oxygen is produced
C) The electrons are also pumped across a membrane
D) Protons are pumped across a membrane, which creates a proton gradient
Protons are pumped across a membrane, which creates a proton gradient
As electrons pass down an ETS, the energy released is used to pump protons across a membrane, generating a proton gradient. NADH often serves as the initial electron donor. It is not produced. Water is only produced when oxygen is the final electron acceptor; in anaerobic respiration, water is not a product.
Which type of metabolism is considered the most efficient?
A) Anaerobic
B) Fermentation
C) Aerobic
Aerobic
Aerobic respiration is the most efficient with the ability to produce up to 38 ATP. Anaerobic respiration produces variable amounts of ATP (5-36) depending on the final electron acceptor used. Fermentation produces a net of 2 ATP, which makes it the least efficient pathway.
In both fermentation and respiration:
A) NAD+ is regenerated from NADH
B) Pyruvate is further oxidized to CO2
C) Protons are pumped across a membrane
D) NADH is produced
A) NAD+ is regenerated from NADH
____ ____ involves reactions wherein organic molecules donate electrons to oxygen to form water
Aerobic organotrophy
In ____ ____, the organic molecule donates electrons to non-oxygen electron donors such as nitrate, sulphates etc
anaerobic organotrophy
In ____ ____, inorganic molecules donate electrons to oxygen
aerobic lithotrophy
In respiration, glycolysis produces two ATP, two NADH2 and two pyruvate from one molecule of glucose. The pyruvate is then converted to ?
acetyl-CoA
Only in ____ fermentation, is CO2 produced. No CO2 is produced in ____ fermentation.
ethanol; lactic acid
During glycolysis glucose is oxidized to ____ and NAD+ is reduced to ____.
NAD+; NADH
A cell that uses an organic carbon source and obtains energy from light would be called which of the following? Choose one: A) Chemoautotroph B) Chemoheterotroph C) Photoheterotroph D) Photoautotroph
C) Photoheterotroph
As electrons are passed down an electron transport system, Choose one:
A. protons are pumped across a membrane
B. NADH is produced.
C. the electrons are also pumped across a membrane
D. H2O is produced
A. protons are pumped across a membrane
Which statement is accurate about the role of cellular enzymes? Choose one:
A. They increase reaction rates by increasing activation energy.
B. They control where and when reactions occur by decreasing activation energies.
C. They store the cell’s hereditary information.
D. They allow reactions with a positive ΔG to occur.
B. They control where and when reactions occur by decreasing activation energies.
Before feeding into the TCA cycle, pyruvate is first converted to:
A. FADH2
B. acetyl-CoA
C. citrate
D. NADH
B. acetyl-CoA
Which of the following molecules can donate electrons in metabolic reactions? Choose one:
A. ADP
B. ATP
C. NAD+
D. NADH
D. NADH
Which of the following accurately describes the entropy changes that occur in living cells and their surroundings? Choose one:
A. Entropy decreases in both cells and their surroundings
B. Entropy increases in both cells and their surroundings
C. Entropy increases in cells but decreases in their surroundings
D. Entropy decreases in cells but increases in their surroundings
D. Entropy decreases in cells but increases in their surroundings
Most ATP generated during the cellular
respiration of glucose is made by ?
oxidative phosphorylation
The energy of this proton motive force can be harnessed by allowing hydrogen ions to diffuse back through the membrane by ____ using ____.
chemiosmosis; ATP synthase
____ uses an organic molecule as a final electron acceptor to regenerate NAD+ from NADH so that glycolysis can continue.
Fermentation
____ does not involve an electron
transport system.
Fermentation
Which of the following is an organism that obtains its energy from the transfer of electrons originating from chemical compounds and its carbon from an inorganic source?
A. chemoautotroph
B. chemoheterotroph
C. photoheterotroph
D. photoautotroph
A. chemoautotroph
Which of the following molecules is reduced?
A. NAD+
B. FAD
C. O2
D. NADH
D. NADH
Which of the following are organic molecules that help enzymes work correctly?
A. cofactors
B. coenzymes
C. holoenzymes
D. apoenzymes
B. coenzymes
Which of the following products is made during Embden-Meyerhof glycolysis?
A. NAD+
B. pyruvate
C. CO2
D. two-carbon acetyl
B. pyruvate
Which is the location of electron transports systems in prokaryotes?
A. the outer mitochondrial membrane
B. the cytoplasm
C. the inner mitochondrial membrane
D. the cytoplasmic membrane
D. the cytoplasmic membrane
Which is the source of the energy used to make ATP by oxidative phosphorylation?
A. oxygen
B. high-energy phosphate bonds
C. the proton motive force
D. Pi
C. the proton motive force
A cell might perform anaerobic respiration for which of the following reasons?
A. It lacks glucose for degradation.
B. It lacks the transition reaction to convert
pyruvate to acetyl-CoA.
C. It lacks Krebs cycle enzymes for processing
acetyl-CoA to CO2.
D. It lacks a cytochrome oxidase for passing
electrons to oxygen.
D. It lacks a cytochrome oxidase for passing
electrons to oxygen.
In prokaryotes, which of the following is true?
A. As electrons are transferred through an ETS, H+ is pumped out of the cell.
B. As electrons are transferred through an ETS, H+ is pumped into the cell.
C. As protons are transferred through an ETS, electrons are pumped out of the cell.
D. As protons are transferred through an ETS, electrons are pumped into the cell.
A. As electrons are transferred through an ETS, H+ is pumped out of the cell.
Which of the following is the purpose of fermentation?
A. to make ATP
B. to make carbon molecule intermediates for anabolism
C. to make NADH
D. to make NAD+
D. to make NAD+
Which molecule typically serves as the final
electron acceptor during fermentation?
A. oxygen
B. NAD+
C. pyruvate
D. CO2
C. pyruvate
