1. Fill in the blanks:
The more (a) ______________ a molecule is, the more potential energy it has to be used in reactions by the cell. CO2 is a completely (b) _____________ form of carbon.
In Glycolysis, the cell consumes (c) _____ ATP and produces (d) _____ ATP (excluding oxphos), with a net (e) ____ ATP produced.
Cancerous cells have higher than normal energy demands, but heavily rely on glycolysis (a form of (f) ______________ phosphorylation) to produce much of the cell’s ATP, instead of oxidative phosphorylation.
2. You learned in the previous question that cancerous cells don’t rely on oxidative phosphorylation for most ATP production. Why is this counter-intuitive?
3. a) An undergraduate student from UBC visits San Francisco and rents a (very heavy) quadricycle with his friends. After biking up a very steep hill, he notices that his thighs are burning and are in a lot of pain. Half an hour later, they feel fine. What is he experiencing?
b) The simplified chart below shows how a human muscle cell may produce energy in the low oxygen conditions. What does each of the letters represent?
- a) Reduced
- Oxidative phosphorylation carried out by the Electron Transport Chain produces much more energy for each molecule of glucose than only glycolysis. Cancer cells have higher energy demands, so reasoning states that they’d try to get as much energy as possible from each molecule of glucose.
- a) His pain was caused by lactic acid build-up, a result of fermentation due to his muscles not getting enough oxygen. This build-up (and pain) was cleared in the next half an hour. (Note: Humans can’t carry out ethanol fermentation)
b) A = Glycolysis, B = pyruvate, C = Lactic Acid Fermentation, D = Lactate
c) The cell needs to convert NADH back to NAD+ for glycolysis. If the cell runs out of NAD+, then no glycolysis (and therefore no ATP made by substrate-level phosphorylation) can occur!
0 ATP is made by fermentation itself.
Reminders for your exam:
- Do you have the right date? (April 12th?)
- Don’t know the answer to a MCQ question? Use the process of elimination to increase your chances.
- Don’t forget to bring your cheat sheet! Haven’t memorized the inputs and outputs of each metabolic cycle? Write that down.
- Read each question carefully! (i.e. if a question asks how much ATP glycolysis produces, does it include ATP produced by the NADH that glycolysis produces?)