Chapter 2: Cellular Respiration Flashcards
Photoautotrophs
Organisms that can build all the organic compounds required for life from simple inorganic materials, using light in the process.
Heterotrophs
Organisms that feed on other organisms to obtain chemical energy.
Chemoautotrophs
Organisms that can build all the organic compounds required for life from simple inorganic materials without using light energy.
Aerobic Cellular Respiration
Harvesting energy from organic compounds using oxygen.
Obligate Anaerobes
Organisms that cannot live in the presence of oxygen and obtain energy by oxidizing inorganic substances.
Obligate Aerobes
Organisms that obtain energy by oxidizing organic substances using oxygen.
Facultative Anaerobes
Organisms that obtain energy by oxidizing inorganic substances with or without oxygen.
Substrate-level Phosphorylation
Mechanism forming ATP directly in an enzyme-catalyzed reaction.
Oxidative Phosphorylation
Mechanism forming ATP indirectly through a series of enzyme-catalyzed redox reactions (oxidation and reduction) involving oxygen as the final electron acceptor.
The final product from the electron transport chain that contains most of the electrons in which of the following?
Water
In which of the following forms is energy immediately made available for use by living cells?
ATP
The major advantage of aerobic respiration to humans is that we…
Obtain more usable energy by aerobic respiration.
At the end of glycolysis, most of the energy originally found in glucose is located in the molecules of…
Pyruvate
Differences between aerobic and anaerobic respiration.
Aerobic has a higher energy efficiency and anaerobic has a lower one. The products of Aerobic are water and carbon dioxide where the products of anaerobic are lactate or ethanol and carbon dioxide.
Explain how fats can be used to release free energy to help with our metabolic needs.
- fats cannot be used directly to produce energy for a cell.
- First, fat must be hydrolyzed into glycerol and fatty acids. The glycerol can enter glycolysis after either being converted to glucose (via gluconeogenesis) or changed into dihydroxyacetone phosphate (DHAP).
- The fatty acids are broken down to two-carbon units (acetyl-CoA) in a process called β-oxidation, which can be fed directly into krebs cycle.
Briefly explain how ATP is formed from NADH by the electron transport chain and chemiosmosis.
Electrons from NADH are passed to the enzyme NADH dehydrogenase, which is embedded in the inner mitochondrial membrane. The hydrogen that is released from the NADH is pumped to the intermembrane space, thus establishing a proton and pH gradient. The electrons move from electron carrier to electron carrier in the intermitochondrial membrane in a series of redox reactions and ultimatley combine with oxygen and protons at the cytochrome oxidase complex to form water, As electrons move along this pathway more protons, from the dissosiation of FADH2 are pumped from the matrix to the intermembrane space adding to the proton and pH gradient. The protons from the intermembrane space return to the matrix via special ATP synthase molecules embedded in the inner mitochondrial membrane. As they do, they help to catalyze the formation of ATP from ADP and P.
Pyruvate (pyruvic acid) is an interesting molecule because there are so many possibilities for what can happen to it. Describe what the various fates of pyruvate are and under what circumstances these different pathways are used.
.
Aerobic respiration involves which of the following?
The release of energy in cells with an adequate supply of oxygen.
The following molecules can be found at various stages during cellular respiration:
I. acetyl-CoA
II. Carbon Dioxide
III. Glucose
IV. Glyceraldehyde
V. Pyruvate
Which of the following sequences represents the above molecules in order from the largest to the smallest amount of chemical energy?
Glucose, Glyceraldehyde, Pyruvate, acetyl-CoA, Carbon Dioxide
In which of the following situations would you LEAST expect to find anaerobic respiration occuring?
a) a vat in which beer is being manufactured
b) a human brain engaged in writing this test
c) The inside of a bacterium living inside a human intestine
d) a runner’s leg muscle during a 400-m dash
e) the sediments at the bottom of a pond
A human brian enganged in writing this test.
During cellular respiration, the oxygen we inhale ends up in the carbon dioxide we exhale.
False. During cellular respiration the oxygen we inhale ends up in the water we exhale or cecrete.
Overall, glycolysis is an endergonic process.
False, it is an exergonic process.
Electrons combine with oxygen and protons at the end of the electron transport chain.
True
The following reaction takes place in animal cells but not in plant cells:
C6H12O6 + 6 O2 6 CO2 + 6 H2O
False
Pyruvate is a three-carbon compound that is converted into acetyl-CoA in the mitochondrial matrix before entering the Krebs cycle.
True
NADH is reduced by the first protein complex of the electron transport chain.
False. NADH is oxidized by the first protein complex of the electron transport chain.
If a poison blocks the flow of protons through ATP synthase, the Krebs cycle will continue, but glycolysis will not.
False. If a poison blocks the flow of protons through ATP synthase, the Krebs cycle stops, but glycolysis will continue.
Only the amino group of amino acids can be used for energy.
False. The amino group is first removed from the amino acid as waste and the rest of the amino acid is modified prior to entering glycolysis or the Krebs cycle.
In oxidative phosphorylation, 2 NADH and 1 FADH2 theoretically produce 8 ATP.
True
Fermentation oxidizes NADH to NAD+ so that glycolysis can continue.
True
Maximum oxygen consumption, VO2 max, increases as people grow older.
False. Maximum oxygen consumption, VO2 max, decreases as people grow older.
The complete oxidation of glucose to carbon dioxide and water has a G of 2870 kJ/mol glucose. Aerobic respiration captures about 930 kJ of this energy. What happens to the rest of the energy?
It is lost as heat and an increase in entropy.
In glycolysis, glucose must first be activated. Which of the following does this require?
two molecules of ATP
Why is anaerobic respiration less efficient than aerobic respiration?
a. Fewer molecules of ATP are produced per glucose processed.
b. Glucose is not completely oxidized to CO2 and H2O.
c. The potential energy of NADH is not transferred to ATP.
d. The electron transport system is not used.
All of the Above
Which of the following is a product of lactate fermentation?
NAD+
When the supply of acetyl-CoA exceeds the demand for energy, some of the acetyl-CoA can be diverted toward the synthesis of which one of the following?
fatty acids
Cyanide poisoning occurs because cyanide binds cytochrome oxidase, preventing it from transferring electrons to the final electron acceptor of the mitochondrial electron transport chain. What is that acceptor molecule?
O2
If the ATP level of a cell becomes too high, ATP can bind to phosphofructokinase and block the formation of fructose 1,6-bisphosphate. This is an example of which of the following?
feedback inhibition
Which of the following is associated with increased levels of aerobic fitness?
a high VO2 max
When oxygen is scarce in human muscle tissue, ethanol fermentation takes place to keep glycolysis running
False. The correct answer would be lactate fermentation.
In the absence of oxygen, human muscle cells convert pyruvic acid to lactic acid to keep resupplying glycolysis with NAD+.
True
Nicotinamide Adenine Dinucleotide (NAD+)
Coenzyme used to shuttle electrons to the first component of the electron transport chain in the mitochondrial inner membrane.
Glycolysis
A process for harnessing energy in which a glucose molecule is broken into two pyruvate molcules in the cytoplasm of a cell.
Mitochondria
Eukaryotic cell organelle in which aerobic cellular respiration occurs.
Eukaryotic Cells
Cells possessing no intracellular membrane-bound organelles or nucleus.
Cristae
The folds of the inner mitochondrial membrane
Matrix
The fluid that fills the interior space of the mitochondrion.
Intermembrane Space
The fluid filled space between the inner and outer mitochondrial membranes
Krebs Cycle
A cyclic series of reactions that transfers energy from organic molecules to ATP, NADH, and FADH2 and removes carbon atoms as CO2.
Electron Transport Chain
A series of membrane-associated protein complexes and cytochromes that transfer energy to an electro-chemical gradient by pumping H+ ions into an intermembrane space.
Electrochemical Gradient
A concentration gradient created by pumping ions into a space surrounded by a membrane that is impermeable to the ions.
Proton Motive Force (PMF)
A force that moves protons through an ATPase complex on account of the free energy stored in the form of an electrochemical gradient of protons across a biological membrane.
Chemiosmosis
A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.
Metabolic Rate
The amount of energy consumed by an organism at a given time.
Basal Metabolic Rate (BMR)
The minimum amount of energy on which an organism can survive.
Nomograms
Graphical methods for determining the value of an unknown quantity when the values of other quantities that is mathematically related to are known.
Deamination
The first step in protein catabolism, involving the removal of the amino group of an amino acid as ammonia.
β-oxidation
The sequential removal of acetyl groups in the catabolism of fatty acids.
Fermentation
A process in which the hydrogen atoms of NADH are transferred to organic compounds other than an electron transport chain.
Ethanol Fermentation
A form of fermentation occurring in yeast in which NADH passes its hydrogen atoms to acetaldehyde, generating carbon dioxide, ethanol and NAD+.
Lactate (lactic acid) Fermentation
A form of fermentation occurring in animal cells in which NADH transfers its hydrogen atoms to pyruvate, regenerating NAD+ and lactate.
Oxygen Debt
The extra oxygen required to catabolize lactate to CO2 and H2O
Aerobic Fitness
A measure of the ability of the heart, lungs and bloodstream to supply oxygen to the cells of the body during physical exercise.
Maximum Oxygen Consumption, VO2max
The maximum volume of oxygen, in mililitres, that the cells of the body can remove from the bloodstream in one minute per kilogram of body mass while the body experiences maximal exertion.
Series of membrane-bound electron carriers in the ETC
Cytochromes
Metabolism in the absence of oxygen
Anaerobic Respiration
End Product of Glycolysis
Pyruvate
Reactions involved in the synthesis of biological molecules.
Anabolism
Cyclic series of reactions in which pyruvate is oxidized to CO2 and H2O
Citric Acid Cycle (Krebs Cycle)
Reactions that involve the release of free energy
Exergonic
Large enzymes that remove carbon dioxide from pyruvate
Decarboxylation
The “priming” of glucose by the addition of a phosphate.
Phosphorylation
The location for the cell in glycolysis
Cytoplasm
ATP generation using a proton pump/ diffusion of H+ ions
Chemiosmosis
Reactions that require the addition of energy
Endergonic
Reactions in which a molecule gains electrons
Reduction
The process by which a molecule gains a phosphate group.
Substrate Level Phosphorylation
The ketone which is an isomer of PGAL
DAP
ATP formation using PEP and an enzyme catalyzed reaction
Substrate Level Phosphorylation
Series of respiratory proteins bound in the mitochondrial membrane which function to generate ATP
Electron Transport Chain
Intermediate compound produced from the oxidation of pyruvate which enters the citric acid cycle.
Acetyl- CoA
The structural isomer of glucose6phosphate
fructose6phosphate
Reactions in which a molecule loses electrons
Oxidation
One by-product of microbial fermentation
Ethanol
The location of the electron transport chain
Inner Mitochondrial Membrane
Reactions that break down large complex molecules
Catabolism
Enzyme that regulates respiration by allosteric effect and precurser activation
Phosphofructokniase
The product of anarobic respiration in muscle cells
Lactic Acid
Anaerobic breakdown of glucose
Glycolysis
“Reduced” form of most important electron carrier
NADH
The biochemical pathway which releases energy in cells
Cellular Respiration
The oxidized form of nicotinamide adenine dinucleotide
NAD+
The oxidation of glucose in the presence of oxygen
Aerobic Respiration
Compound which forms a complex with coenzyme A before entering the krebs cycle
Acetyl
The process whereby glucose is split into 2 pyruvate.
Glycolysis
