Download Alcoholic fermentation

Chapter 9 Study ?’s (part 3): Electron Transport Chain / Alternate Metabolic Pathways
Alternative Metabolic Pathways- KEY
9) Create a chart in which you compare the processes of: alcohol fermentation and lactic acid fermentation.
Summarize the inputs and outputs of each, and examples of organisms that perform each process.
Inputs
Outputs
Ex:
Alcoholic fermentation
2 pyruvate
2 CO2, NAD+, ethanol
Yeast; some bacteria
Lactic acid fermentation
2 pyruvate
NAD+, lactate (lactic acid) Muscle cells at the cellular
level; some bacteria
10) In lactic acid fermentation,
a) what is caused by a build-up of lactate in muscle cells?
Muscle pain; fatigue
b) what happens to the accumulated lactate?
Carried to the liver where it is converted to pyruvate
11) Describe 3 lines of evidence that glycolysis is one of the “oldest” metabolic pathways.
1) oldest known fossils are over 3.5 billion years old and oxygen was not plentiful until 2.5 billion years ago
2) most widespread metabolic pathway (shows it evolved early)
3) location (cytosol) does not require a membrane enclosed organelle
12) We have learned how glucose is processed through cellular respiration. In the space below, summarize how
proteins and fats are used as sources as fuel. Include the energy content of fat as compared to that of carbohydrates.
 Starches and glycogen are hydrolyzed to glucose; proteins are hydrolyzed to amino acids and the extra
amino acids are converted by enzymes to intermediates of glycolysis and Kreb’s cycle; fats are converted to
intermediates of glycolysis and fatty acids are converted and enter Kreb’s cycle

1 gram of fat produces twice as much ATP as 1 gram of carbohydrates
13a) How does a cell use feedback inhibition to control its catabolism?
As ATP concentration decreases, respiration speeds up; as ATP concentration increases, respiration slows down
(regulated by enzymes)
13b) What is the role of the enzyme phosphofructokinase in this feedback inhibition?
It catalyzes step #3 of glycolysis; it is the “pacemaker” of respiration; this step commits the substrate
irreversibly to glycolysis
13c) How are ATP and ADP involved in the regulation of the enzyme phosphofructokinase?
Phosphofructokinase is inhibited by ATP and stimulated by AMP; the enzyme has an allosteric site with
receptor sites specific for inhibitors & activators
13d) How is phosphofructokinase also regulated by the Krebs cycle?
Phosphofructokinase is also sensitive to citrate (the 1 st product of Kreb’s); if citrate accumulates in the
mitochondria, some of it passes to the cytosol and inhibits phosphofructokinase; this helps synchronize
Glycolysis and Kreb’s