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Polymase is formed by

  • several ribosomes attached to a single mRNA

  • many ribosomes attached to a strand of endoplasmic reticulum

  • a ribosome with several subunits

  • a ribosome with several subunits


A.

several ribosomes attached to a single mRNA

In prokaryotes, ribosomes attach to the 5 end of mRNA as soon as transcription begins. A bunch of ribosome moves along a single m RNA molecules adding 15 amino acids second to the polypeptide chain, almost the same speed at which RNA polymerase transcribes the mRNA. The group of ribosomes together with single mRNA molecules, they are translating is called polysome. The use of polysomes si advantageous to a cell since the overall rate of protein synthesis is increased compared to the rate that would occur if there were no polysomes.

In eukaryotic cells, the ribosomes are attached to rough endoplasmic reticulum by ribophorin protein.Electron microscopy reveals that membranes of homogenised reveal that membranes of homogenised endoplasmic reticulum disrupt to form closed vesicles called microsomes.

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Cry-I endotoxins obtained from Bacillus thringiensis are effective against 

  • mosquitoes

  • flies

  • nematodes

  • nematodes


What is antissense technology? 

  • A cell displaying a foreign antigen used for synthesis of antigens

  • Production of somaclonal variants in tissue cultures. 

  • When a piece of RNA that is complementary to sequence is used to stop expression of a specific gene.

  • When a piece of RNA that is complementary to sequence is used to stop expression of a specific gene.


Which one of the following pairs of nitrogenous bases of nucleic acids, is wrongly matched with the category mentioned against it?

  • Thymine, Uracil - Pyrimidines

  • Uracil, Cytosine - Pyrimidines

  • Guanine, Adenine - Purines

  • Guanine, Adenine - Purines


In the DNA molecule

  • the  total amount of purine nucleotides and pyrimidine nucleotides is not always equal

  • there are two strands, which run parallel in the 5' →3' direction

  • the proportion of adenine in relation to thymine varies with organism

  • the proportion of adenine in relation to thymine varies with organism


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