CH. 7 Sapling HW
When a person is sprinting, the person's muscle cells will begin using anaerobic respiration in addition to keeping the mitochondria respiring aerobically as much as the oxygen supple will allow. What benefits do muscle cells gain from anaerobic respiration in this situation?
- adding electrons from NADH to pyruvate regenerates NAD+, so that glycolysis can continue, and produces lactic acis, a waste product that can diffuse out of the cell - without using oxygen, the cell generates two ATP molecules that can keep the muscles moving for every glucose molecule that enters glycolysis
Gylcolysis is a step in the breakdown of glucose. Which of the following statements describe gylcolysis?
- it is common to aerobic and anaerobic respiration - it breaks down glucose to two pyruvate molecules
The pyruvic acid from glycolysis can be converted to acetic acid, which can enter the citric acid cycle. Because this process is a cycle, the atoms entering the cycle must balance the atoms that leave. Consider carbon balance in the citric acid cycle. How many CO2 molecules leave the cycle for each acetic acid molecule that enters? For this question, assume that carbon only enters as acetic acid and exits as CO2. Note that acetic acid has two carbon atoms. You can determine the number of carbon atoms in carbon dioxide from its formula, CO2.
2 CO2 atoms
During glycolysis, glucose is broken down into two molecules of pyruvic acid. How many carbon atoms are in each pyruvic acid molecule?
3 carbon atoms
Using the above answer, how many molecules of CO2 are directly generated by the citric acid cycle from 2 molecules of acetic acid? Again, in this question assume that carbon only enters as acetic acid and exits as CO2.
4 CO2 atoms
A product that can be used directly for energy
ATP
The direct energy source for glycolysis
ATP
Which molecule is used as the primary source of chemical energy for tasks within a cell?
ATP
Cellular respiration is carried out in the presence of oxygen (aerobic conditions) or the absence of oxygen (anaerobic conditions). Determine whether each of the following occur under aerobic conditions, anaerobic conditions, or both aerobic and anaerobic conditions
Aerobic Conditions: - citric acid cycle (Krebs cycle) - electron transport chain Anaerobic Conditions: - fermentation Both: - glycolysis
Identify compounds that are required for the electron transport chain and compounds that are produced by the electron transport chain.
Compounds that enter the electron transport chain: - NADH - FADH2 - O2 - ADP Compounds produced by the electron transport chain: - NAD+ - FAD - H2O - ATP
What disrupts cellular respiration by destroying the proton gradient in the mitochondrion?
DNP (diet pill)
Compare and contrast lactic acid fermentation and ethanol fermentation (alcohol fermentation).
Ethanol Fermentation: - used by yeast cells - generates ethanol Lactic Acid Fermentation: - used by animal cells - produces lactic acid (lactate) Both: - occurs under anaerobic conditions - regenerates NAD+ that can be used in glycolysis
T/F An ATP molecule contains the nitrogenous base guanine
False
T/F An ATP molecule contains three AMP molecules
False
T/F High-energy phosphate bonds in ATP link the phosphate groups and the base adenine
False
Place the steps of glycolysis in the order that they occur
First Step - glucose is converted to glucose-6-phosphate by hexokinase - phosphoenolpyruvate is converted to pyruvate - fructose-6-phosphate is phosphorylated by phosphofructokinase - 3-phosphoglycerate is formed -glyceraldehyde-3-phosphate is converted to 1, 3 bisphosphoglycerate - aldolase cleaves the six-carbon sugar into two three-carbon sugars Last Step
A product that donates electrons to the electron transport chain
NADH
T/F ATP contains ribose, a five-carbon sugar
True
T/F ATP has three phosphate groups
True
T/F ATP is a nucleotide containing a base, a sugar, and phosphate groups
True
Identify the oxidized substance, the reduced substance, the oxidizing agent, and the reducing agent in the following redox reaction: Fe(s) + Cu2+(aq) --> Fe2+(aq) + Cu(s)
Which substrate gets oxidized - Fe Which substrate gets reduced - Cu2+ What is the oxidizing agent - Cu2+ What is the reducing agent - Fe
In general, what happens during an oxidation-reduction reaction between two molecules?
an atom in the reduced molecule attracts an electron that an atom in the oxidized molecule donates
What disrupts cellular respiration by stalling the conversion of pyruvate to acetyl-CoA?
arsenic
Breakdown of glucose to pyruvate
cytosol
Anaerobic respiration allows a cell to break down carbohydrates in the absence of oxygen. Identify how NAD+ is used by animal cells during anaerobic respiration.
during fermentation, NAD+ is generated from NADH and is used to continue glycolysis
Amino acids can be used as fuel during cellular respiration once the nitrogen-containing amine groups have been removed from them. When do amino acids that have had their amine groups removed enter the pathways of cellular respiration?
during the Krebs cycle or during glycolysis
Cytochromes are critical participants in the electron transport chains used in photosynthesis and cellular respiration. How do cytochromes donate and accept electrons?
each cytochrome has an iron-containing heme group that accepts electrons and then donates the electrons to a more electronegative substance
The electron transport chain uses the transfer or __________ between protein complexes to set up a proton gradient.
electrons
A proton gradient is formed in the mitochondria such that the concentration of protons (H+) is higher on one side of the inner mitochondrial membrane than on the other side. What is the purpose of this proton gradient?
generates ATP in the electron transport chain
A carbohydrate that enters glycolysis directly
glucose
Which of the following describes the effect of cyanide on cellular respiration?
inhibits the function of cytochrome c oxidase in the electron transport chain
What is the function of the proton gradient in the mitochondria?
it is potential energy that the cell uses to generate ATP
What disrupts cellular respiration by stalling the electron transport chain?
low oxygen
Citric acid cycle
mitochondrial matrix
Conversion of pyruvate to acetyl-CoA
mitochondrial matrix
The majority of ATP is generated
mitochondrial membrane
Cellular respiration cnsumes glucose during glycolysis. What product of glycolysis can be subsequently modified to enter the citric acid cycle under aerobic conditions?
pyruvate
An end product that is modified to enter the citric acid cycle
pyruvic acid
Pyruvate is a product of glycolysis and is subsequently converted to acetyl-CoA. Acetyl-CoA is a substrate for the citric acid cycle (CAC). Exactly how many molecules of glucose must be oxidized in glycolysis to provide the input for tour turns of the CAC?
two
Although the path of one glucose molecule through glycolysis generates a total of four ATP molecules, there is a net gain of only two ATP for each glucose molecule that enters the pathway. Why does the passage of one glucose molecule through glycolysis have a payoff of only two ATP molecules?
two ATP molecules are used in the initial phase of glycolysis, reducing the net gain of two ATP