"80-S" ribosome is formed by the combination of:
Correct answer: D. 60S and 40S
- A. 30S and 40S
- B. 70S and 10S
- C. 50S and 30S
- D. 60S and 40S
Explanation
Ribosomes are non-membrane-bounded organelles that are present in large numbers in all living cells and serve as the site of protein synthesis. Ribosomes occur both as free particles in prokaryotic and eukaryotic cells and as particles attached to the membranes of the endoplasmic reticulum in eukaryotic cells. Each ribosome is composed of two subunits, a larger one and a smaller one, each of which has a characteristic shape. Ribosomes are the sites at which information carried in the genetic code is converted into protein molecules. 80S ribosomes are found in eukaryotic cells. 80S ribosomes contain a small 40S subunit and a large 60S subunit. The large subunit (the 60S) catalyzes the formation of the peptide bond, and the small 40S ribosomal unit holds the mRNA molecule so that tRNA can compare and attach amino acids to it.
This question appeared on the ETEA MDCAT 2015 paper, which you can sit online with every answer explained.
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About Ribonucleic Acid (RNA)
Ribonucleic acid is generally a single-stranded nucleic acid containing ribose and uracil instead of thymine. Coverage includes mRNA, tRNA and rRNA, complementary base pairing, transcription and translation, and the differences between RNA and DNA in structure, location and biological function.
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