Multiple Choice
In translation, which type of RNA brings amino acids to the ribosome by matching its anticodon to mRNA codons?
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5. DNA to RNA to Protein
tRNA, rRNA and the Codon Code
Multiple Choice
In the context of tRNA, rRNA, and the genetic code, what is the sedimentation coefficient (size) of a typical eukaryotic cytosolic ribosome?
A
60S
B
80S
C
90S
D
70S
Verified step by step guidance1
Understand that the sedimentation coefficient (Svedberg unit, S) reflects the size and shape of ribosomal subunits and the whole ribosome, not a simple sum of the parts because it depends on how particles sediment during centrifugation.
Recall that eukaryotic cytosolic ribosomes are composed of two subunits: the large 60S subunit and the small 40S subunit.
Recognize that when these two subunits combine to form the complete ribosome, the sedimentation coefficient is not additive (i.e., 60S + 40S ≠ 100S) due to the complex interactions and shape of the assembled ribosome.
Know from cell biology that the assembled eukaryotic cytosolic ribosome has a sedimentation coefficient of 80S, which is characteristic of eukaryotic ribosomes.
Therefore, the correct sedimentation coefficient for a typical eukaryotic cytosolic ribosome is 80S.
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