Question

LOJL B) glucose C) galactose D) fructose 2. Define the term “polycistronic." Make sure you use the terms "promoter," "terminator," "ribosomal binding site," "start codon," and "stop codon” in your answer, a diagram might be helpful as a part of your answer. 3. Please complete the following table with the terms: "a lot," "a little," or "none. is CAP- CAMP complex is repressor bound? is RNA pol bound? i s lac operon transcribed?

Answer 1

Polycistronic is a type of mRNA that codes for multiple different types of protein products. It is generally found in prokaryotes and monocistronic mRNA is usually present in prokaryotes. Due to the presence of polycistronic mRNA prokaryotes have less flexibility while regulating gene expression.

The polycistronic mRNA is formed when the RNA polymerase enzyme is attached to the promoter (P) site of the eukaryotic DNA that initiates the transcription process of the mRNA. The transcription stops when the RNA polymerase reaches the terminator (T) site. Simultaneously, as the transcription process takes places translation also occurs in the polycistronic mRNA where the ribosomal binding site is responsible for recruiting the ribosomes necessary for the ribosomal translation of the mRNA. It is called the  Shine-Dalgarno (SD) sequence and it is located right ahead of the start codon (which is usually AUG). The translation process then ensures the synthesis of the multiple protein products that are coded into the mRNA and the process comes to a halt when the ribosomes come to the stop codon. This process occurs from the 5' to 3' end of the RNA molecule.

RNA polymerase Transcription DNA Gene 1 Gene 2 Gene 3 T Promoter (DNA where RNA pol binds) Genel | Polycistronic mRNA Gene 2 | Gene 3 | Translation Protein 1 Protein 2 Protein 3

NOTE: The ribosomal binding site (SD sequence), start codon and stop codon are not in this diagram refer the next diagram with only the polycistronic mRNA for that.

shine -dalgamo prokaryotic mRNA sve me NCR Y STOP AUGS Start non 4 NCR

NOTE: NCR means Non-coding regions or regions in the mRNA that do not code for any proteins