Lesson 4.4 - Anaerobic Pathways: Life Without Oxygen Flashcards
Define Alcohol Fermentation
A process in which pyruvate is decarboxylated, producing a molecule of CO2, ethanol, and an NAD+.
What is a process in which pyruvate is decarboxylated, producing a molecule of CO2, ethanol, and an NAD+ known as?
Alcohol Fermentation
Define Lactate Fermentation
A process in which pyruvate reacts with NADH and is converted directly into lactate and regenerates NAD+.
What is a process in which pyruvate reacts with NADH and is converted directly into lactate and regenerates NAD+ known as?
Lactate Fermentation
Fermentation pathways enable organisms to use _____ as a source of ATP, without an _____ transport chain.
Fermentation pathways enable organisms to use glycolysis as a source of ATP, without an electron transport chain.
Alcohol fermentation is performed by _____ and has significant commercial value.
Alcohol fermentation is performed by yeast and has significant commercial value.
Lactate fermentation in muscles provides a supplementary source of _____ when energy demands are very high.
Lactate fermentation in muscles provides a supplementary source of ATP when energy demands are very high.
_____ respiration uses inorganic substances other than O2 as terminal electron acceptors in an electron transport chain.
Anaerobic respiration uses inorganic substances other than O2 as terminal electron acceptors in an electron transport chain.
Compare aerobic respiration and fermentation in terms of the amount of ATP that can be generated from a single glucose molecule.
Aerobic respiration and fermentation can generate quite different numbers of molecules of ATP from a single glucose molecule. Cells that rely on fermentation to generate ATP using only glycolysis generate 2 ATP per molecule of glucose. Conversely aerobic respiration uses an electron transport chain and produces approximately 36–38 ATP per molecule of glucose.
Why do cells rely on fermentation rather than glycolysis alone?
If cells relied on glycolysis alone, they would quickly run out of NAD+, a necessary reactant in glycolysis. They rely on fermentation to regenerate the NAD+.
Explain the anaerobic pathway that is used to create a loaf of bread. How does this pathway work?
The alcoholic fermentation pathway is used by bakers to create a loaf of leavened bread. Yeast is mixed with a small amount of sugar and is blended into dough, where oxygen levels are low. As the yeast cells convert the sugar into ethanol and CO2, the gaseous CO2 expands and creates gas bubbles that cause the dough to rise. In the oven, thermal energy evaporates the alcohol and causes further expansion of the bubbles, producing leavened bread.
Do our muscle cells produce alcohol? Given that alcohol and lactate fermentation both yield two ATP molecules for every glucose molecule, do you think it would make any difference which pathway was used? Explain.
No, our muscle cells do not produce alcohol; instead they undergo lactate fermentation under anaerobic conditions. Even though they produce the same number of ATP per molecule of glucose, alcohol is toxic. Producing it in large amounts during strenuous exercise would cause a variety of problems for the cell and for the organism as a whole.
Using what you know about lactic acid fermentation, explain why a person could not perform sternuous exercise indefinitely.
Muscle tissue has a lactate threshold, which is the point of lactic acid buildup at which the acid cannot be carried away from muscle tissue as quickly as it is produced. After reaching this threshold, muscle damage would result and a person would eventually be unable to continue exercising.
Is fermentation considered to be a form of respiration?
No
Does fermentation contain an electron transport chain? Does anaerobic respiration?
Fermentation does not have an electron transport chain, anaerobic respiration does.
