This set of Cell Biology Objective Questions & Answers focuses on “Self-assembling Macromolecules”.
1. Tobacco Mosaic Virus consists of one long molecule of ______________
Explanation: In 1955 at the University of California, it was demonstrated that TMV particles consist of one long molecule of RNA which is 6600nucleotides long wound in a helical capsule made of 2130 identical protein subunits.
2. TMV particles are not capable of self-assembly.
Explanation: In the first experiments conducted in 1955, the RNA and protein components of a TMV were separated and then mixed together. After a brief incubation period, the recovered mixture contained infective particles. This confirmed the self-assembly property in TMV.
3. Ribosomes consist of RNA and _____________
b) nucleic acids
Explanation: Ribosomes consist of different types of RNAs and proteins. Regardless of the source, all ribosomes contain two subunits of different sizes.
4. The large (50S) ribosomal subunit of bacteria contains _______ molecules of RNA.
Explanation: The large (50S) ribosomal subunit of bacteria contains 2 molecules of RNA and approximately 32 different proteins. The smaller 30S subunit contains one RNA molecule and 21 different proteins.
5. Which protein of the smaller subunit of bacterial ribosome was found to have a function in ribososme assembly?
Explanation: The S16 protein of the smaller ribosomal subunit 30S was found to have a function solely in ribosome assembly. The deletion of this protein slowed down the in vitro assembly process.
6. Eukaryotic subunits are not capable of self-assembly.
Explanation: Ribosomal subunits of bacteria are capable of self-assembly whereas those of eukaryotes are not. Transient association of proteins is required in the in vitro synthesis of eukaryotic ribosomes that don’t even end up in the final product.
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