alleryStart learning →Why does the pathway that starts with citrate carry the alternative name TCA cycle?
ABecause it turns three times per glucose
BBecause citrate is a tricarboxylic acid
CBecause it needs three carrier molecules
DBecause three carbon atoms leave each turn
Answer & Solution
Correct answer: B. Because citrate is a tricarboxylic acid
1. The same pathway is called by three different names for three different reasons.
2. It is the citric acid cycle after citrate, the first intermediate formed.
3. It is the TCA cycle because citric acid and isocitrate are tricarboxylic acids.
4. Tricarboxylic acid is shortened to TCA, so the initials come from chemistry rather than counting.
5. Two carbon dioxide molecules leave on each turn, not three, so the carbon-counting option is wrong on its numbers.
6. The number of turns per glucose is a separate matter and plays no part in the naming.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.3 Oxidation of Pyruvate and the Citric Acid Cycle_
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