Indicate whether each has a role in transcription, translation, both, or neither

ID: 209405 • Letter: I

Question

Indicate whether each has a role in transcription, translation, both, or neither:

Initiation Site, mRNA, Start Codon, DNA Polymerase, Ribosome Binding Site, Stop Codon, -10/-35 consensus sequence

How many promoters would be necessary to allow transcription of the pmoCAB operon?

How many mRNA molecules will be produced when this operon is transcribed?

How many ribosome binding sites will be present on the RNA produced when the pmo operon is transcribed?

How many start codons and stop codons will be present on the RNA produced when the pmooperon is transcribed?

Explanation / Answer

Transcription

Translation

Both (Transcription & translation)

neither

-10/-35 consensus sequences

stop codon

DNA Polymerase

Initiation Site (+1)

Ribosome Binding Site (RBS)

Start Codon

mRNA

All the proteins which expressed in a cell are coded by the genes which are present in DNA. The RNA polymerase bind to the promoter sequences of DNA and copy the genetic information present in DNA into mRNA by transcription process and then ribosome’s translate this information located in mRNA (in the form of codons) as a protein by a process called translation. The RNA polymerase binds to the promoter regions located in -10 and -35 regions. The consensus sequences present at -10 region in prokaryotes are TATAAT and at -35 region is TTGACA. The promoter regions are located at an upstream portion of a gene and initiate the synthesis of mRNA by denovo fashion. From the transcription bubble (DNA-RNA hybrid), 5 end of mRNA is released into nucleoplasm during transcription processes. The ribosomes bind to mRNA and initiate translation. In prokaryotes, the 5’UTR of mRNA has the Shine Dalgarno sequence which acts as a ribosome binding site but in eukaryotes has Kozak consensus sequence which is similar to the Shine Dalgarno sequence of the prokaryotes.The first codon on mRNA to be translated is AUG (initiation codon/start codon) and it codes for formyl methionine in prokaryotes but in eukaryotes it is methionine. The ribosomes move in 5’ to 3’ direction on mRNA, synthesize the peptide hormone and the N-terminal end of the peptide is released into the cytoplasm.

How many promoters would be necessary to allow transcription of the pmoCAB operon?

Only one promoter

How many mRNA molecules will be produced when this operon is transcribed?

One single polycistronic mRNA

How many ribosome binding sites will be present on the RNA produced when the pmo operon is transcribed?

Only one Shine Dalgarno sequence at 5’UTR of mRNA

How many start codons and stop codons will be present on the RNA produced when the pmooperon is transcribed?

Only one AUG and only one stop codon it may be one of three stop codons (UAA, UAG, UGA)

In the prokaryotes, genes are contiguous without any introns and they are clustered in the form of operons. Each operon has a common promoter and operator site.

The pmoCAB operon codes three subunits of methane monooxygenase protein involved in the conversion of methane to methanol in Methanotrophic bacteria. It is operon has single promoter site to which RNA polymerase binds and synthesize a polycistronic mRNA. The single polycistronic mRNA possess single ribosome binding site called Shine Dalgarno sequence at 5’UTR region. The ribosome bind to the mRNA at single initiation codon/start codon AUG and initiate the translation. When the ribosomes reach the one of the stop codon (UAA, UAG, UGA) in mRNA the translation process is terminated.

I am highly grateful to you if you rate this question