In: Biology
The protein synthesis in pro- and eukaryotic species resembles
each other to a large degree. In both pro and eukaryotic cells,
mRNA is used as template for incorporation of the correct amino
acids in the growing polypeptide chain.
a) List the main differences between mRNA from prokaryotic and
eukaryotic species
b) In contrast to prokaryotic cells, eukaryotic cells has
spliceosomes, what function do they have? and list the main steps
in the reaction
c) How many different codons code for amino acids?
d) Explain why the number of different tRNA molecules is lower,
than the number of different codons?
(a) EukaryoticmRNA is monocistronic in nature that is the mRNA of the eukaryotes is produced by the transcription of the single gene whereas in the prokaryote the mRNA is produced by the transcription of the operons. The transcription in the prokaryote occurs in the cytoplasm as there is no nucleus in the case of prokaryotes.The transcription in case of eukaryotes occurs in the separate compartment known as nucleus. Transcription is the the process by which DNA is converted into RNA. mRNA is also formed through the process of transcription.The prokaryotic DNA contains ribosomes binding site which is known as shine Oalgana sequence. 5' capping in the mRNA occurs in case of the eukaryotic mRNA. The lifespan of prokaryotic mRNA is very short as compared to the eukaryotic mRNA which has a stable lifespan. There is no post transcriptional changes in the case of prokaryotic mRNA. The eukaryotic mRNA undergoes capping tailing and splicing. capping includes the addition of 5- methyl guanosine triphosphate at the 5' end. Tailing includes addition of adenosine group in a template independent manner at 3' end. There are sequence - Introns and exons. Exons are the translatory sequence where introns are non- translatory sequences. Introns are removed and exons are joined to form mRNA.This process is known as splicing.
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