alleryStart learning →An E. coli ribosome is described as 70S. Which two subunits give that value?
AA 20S subunit and a 50S subunit
BA 35S subunit and a 35S subunit
CA 30S subunit and a 50S subunit
DA 40S subunit and a 60S subunit
Answer & Solution
Correct answer: C. A 30S subunit and a 50S subunit
1. In E. coli the small subunit is 30S and the large subunit is 50S.
2. Together they are described as 70S even though 30 and 50 sum to 80.
3. Svedberg units measure how fast a particle sediments during centrifugation, and they are not additive.
4. The 40S and 60S pair belongs to mammalian ribosomes, which total 80S.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 15 "Genes and Proteins", section 15.5 Ribosomes and Protein Synthesis_
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