Purchase Solution

Gene order in yeast Ty element

Not what you're looking for?

Ask Custom Question

Consider the following artificially created yeast Ty element:

See attached file for full problem description.

Upstream from the element has been placed the very strong PGAL promoter which is induced by galactose added to the media. The transcript traverses the whole element (large dashed arrow). Downstream from the normal Ty Open Reading Frames was inserted the yeast HIS3 gene, including its own promoter (small dashed arrow shows transcript), but in reverse orientation. Inserted into the middle of HIS3, and therefore blocking its expression, is an Intervening Sequence (IVS) from another gene. The IVS orientation corresponds to the P GAL transcript (left-to-right).

This construct was placed on a plasmid and transformed into a his3 mutant yeast strain. The transformed strain remained a his auxotroph. However, when grown on solid media containing galactose (but no his), a small number of His+ colonies appeared and grew out of the his- background.

a) What caused the appearance of His+ colonies? How was HIS3 expressed if the gene (as shown) has an IVS disrupting its reading frame?

b) Do you think that the His+ cells require the continued presence of the original Ty containing plasmid to be His+?

c) What would the His phenotype be of a cell transformed with an identical plasmid but with the IVS reversed in direction?

d) What would the His phenotype be of a cell transformed with an identical plasmid but with the HIS3-IVS DNA reversed in direction? (That is, HIS3 now transcribed in the left to-right direction, but the IVS oriented right-to-left).

Attachments
Purchase this Solution
Solution Preview

Upon insertion of the plasmid into the yeast genome it is subject to transcriptional and translational processing. In the presence of galactose the promoter will be activated to transcribe the pre-mRNA.

Gene: P(gal)-5'UTR-TyORF-siH-IVS-siH-3'UTR

premRNA 5'UTR-TyORF-siH-IVS-siH-3'UTR

mRNA 5'UTR-TyORF-siH-siH-3'UTR

protein product Ty (and some His if ribosome attaches to His AUG)

Splicing of the pre-mRNA will remove the IVS from the His transcription unit. IVS normally contain splice acceptor/donator sequence that allows them to be spliced when in the same orientation of the transcript. Normal translation will produce large amounts of Ty protein. There is also the possibility that the ribosome will attach to the His ...

Purchase this Solution
Free BrainMass Quizzes
Breastfeeding Basics

How much do you know about breastfeeding? Find out with this quiz!

BIOLOGY

Basics in biology

How Well Do You Know Your Body?

This quiz will assess the different systems of the human body. It will examine everything from the organs to the cellular processes that occur.

Infant Development: Sleep

How much do you know about infant sleep? Test your knowledge with this quiz.

Creating a Birth Plan

Preparing for a birth and want to make sure that you're including all the right information? Use this quiz to get on the right track and check your birth plan knowledge!

View More Free Quizzes
Related BrainMass Solutions

  • Transposable elements

    In yeast, Ty element are long terminal repeat (LTR) retrotransposons (class I) that must express an RNA intermediate that is then integrated into the genome.

  • Research on Gene Splicing

    The metabolism of xylose to ethanol is very important for the large scale commercial production of ethanol from agricultural wastes and products. (1) In order for yeast to ferment xylose, they must have xylose reductase (XR) enzyme to convert xylose

  • yeast and human genes

    414994 yeast and human genes You have found a yeast gene that appears to encode a DNA polymerase, and you hypothesize that a related gene exists in humans. Describe, in detail, the experiments you would use to test this hypothesis.

  • Complementation Minimal Media Plates

    what would the pattern look like if you included leucine in the agar media? In order to grow on the leucine deficient media, the yeast cells must have the ability to produce leucine, right?

  • Biomedical pathway in the bread mold NEUROSPORA

    You know that compounds A,B,D,E,F are required in this pathway, but you do not know the order in which they are synthesized. In order to study this, you isolate five auxotrophic strains that cannot synthesize compound C.

  • Critique of a scientific research article

    As well, strains of yeast carrying the ACT1-CUP1 reporter constructs were degraded in order to analyse the purported competition between splicing and pre-mRNA degradation. These methods will be further discussed in detail.

  • DNA cloning

    Bacteria are unable to process introns therefore in order to express alpha-globin in a bacterial cell the introns must be removed to create cDNA (compliment DNA which is a DNA copy of the mRNA). 2.

  • Gene Mutation Types

    For example, a mutation in the gene encoding a protein required for creating arginine in yeast is harmless if yeast are grown on media containing arginine. However, if these yeast are grown on medium lacking arginine they will die.

  • Principals of Law

    The only possible element that could change the outcome of this situation is if there is a sign posted in the establishment stating that management assumes no bailment, or assumes no responsibility for lost/damaged/stolen items.

View More Related Solutions