I only need help with Letter E-G. AGAIN E-G 5) The UB food service hands you two
ID: 200024 • Letter: I
Question
I only need help with Letter E-G.AGAIN E-G
5) The UB food service hands you two organisms they found contaminating the drinks, and both organisms were isolated from both milk (lactose containing) and juice (glucose containing) substances, and thus can grow in both substances. We call these organisms S (Starbucks) and C (CVS), based on where they were identified. solate the You want to identify differences in transcription between the two organisms. You i TOTAL RNA, and run the RNA for both S and C organisms on a gel. You identif appear to abundant and very large from a mass point of view. y two large bands on the RNA gel, with many small bands in between. These RNA A) Based on the lectures, these RNA that form these large, prominent bands, are most likely which type of RNA in the cell? Why? rther study transcriptional differences, in the S and C organisms, you add the antibiotic ifampin, which inhibits transcription. You isolate TOTAL RNA and you measure the To fu concentration of RNA. B) What is the simplest way to measure nucleic acid (RNA) concentration? How would you measure the change in RNA concentration? ? Explain. C) Do you expect the RNA to increase, decrease, or remain the same You want to compare transcription in the two organisms, S and C. You fractionate the RNA from both organisms, and you find that the S organism contains mRNA, whereas the C organism contains RNA, but not mRNA. D) What chemical features distinguish mRNA from other types of RNA? Does mRNA exist in both prokaryotes and eukaroytes? Explain. ant to compare transcription under glucose (juice), lactose (milk), and mixed glucose with lactate conditions, in both S and C organisms. You find that when the C organism grow, glucose is first used, and then lactate is consumed. You remember the lecture on lac operon in class. In the C organism, under lactose containing conditions, and you use a probe for a specific DNA equence that encodes for multiple genes involved in lactose metabolism. However, the RNA encoding these genes is not expressed under glucose containing conditions, only under lactose conditions E) How do you explain these findings based on your knowledge of the lac operon? F) What type of organism is C likely to be based on the above data (Bacterial (Prokaryotic) or Yeast/Mammalian (Eukaryotic)? Why? To fully understand transcription in organism C, you perform DNA footprinting. You find that RNA polymerase is bound to the DNA start site that encodes for a single RNA that is increased
Explanation / Answer
E. As we know, lac operon is only used when no glucose is present in media and only lactose is present. when glucose is present, lac operon will not be transcribes, because glucose serves as a catabolite repressor. glucose inhibits the transcription of lac operon. so first glucose is utilized, then in glucose deficient condition. only lactose is present. This induces the transcription of lac operon.and then lactose is utilized by organism C.
F. organism C is a bacteria. because in general only prokaryotes (bacteria) has operons. recently it was found that some eukaryotes has operon but they are mono cistronic. lac operon is a polycistronic one. only bacteria can have a lac operon.
G. initiation site is promoter site. 5' to 3' direction, the sequence is TATAAT this is at -10 region. this is known as tata box. and one is situated at -35 region. sequence is TTTACA.
lac operon produces a polycistronic mRNA. it produces a single primary transcript containing genes for beta galactosidase, permease and transacetylase. all 3 genes are under a single promoter and operator