Ella was completing PCR on a segment of DNA in order to use it for subsequent testing. The DNA segment she wants to amplify has the following code:
T T A C A T G A C G T C A
a) What is the complementary sequence to this code? (1 mark)
b) Explain the steps Ella will need to go through in order to successfully complete PCR. Ensure you reference the temperatures and inputs of each step. (4 marks)
c) This DNA segment is a part of a group of linked genes found in bacteria such as E. coli, and is a segment of the lac operon. Explain what occurs when lactose is abundant and glucose is not in terms of gene expression, in reference to the lac operon. (3 marks)
a) AATGTACTGCAGT
b)
- Ella would need to isolate the DNA segment from the rest of the DNA
- Heat the solution containing the DNA segment to 92ºC, denaturing DNA to separate the DNA into two single strands of DNA.
- Cool the solution to 55ºC and add primers which would attach to complementary DNA sequence.
- Heat the solution to 72ºC and add Taq Polymerase. This would result in the production of copies of the DNA segment.
- The process is repeated multiple times to amplify the DNA segment to the required amount.
c)
- The lac operon is an inducible operon. When lactose is present it binds to the allosteric site of the repressor protein.
- Resulting in a conformation change in the repressor protein, the shape of the active site is altered. Thus, it is unable to bind to the operator region.
- Hence, DNA polymerase is able to bind to the promoter region of the lac operon and transcribe the structural proteins. Therefore, gene expression occurs when lactose is present.
Here’s a few questions for you!
Imagine that we are living in a pandemic, and a nasty virus that is highly virulent is spreading through the globe. You are a virologist who is trying to find a vaccine for this virus – known as coronavirus. A different strain of coronavirus has previously infected the world. a) Why would a vaccine be effective in this situation (hint: herd immunity) and how would a vaccine against coronavirus work? (4 marks)
b) Which kind of drugs will be effective against the virus? Give an example of how a drug might work (2 marks)
c) Describe the process by which this drug can be produced? (hint: Rational Drug Design) (3 marks)
d) What are strategies (other than lockdown, wearing masks and washing your hands) can the government introduce to deal with limiting the spread of this contagious virus? (2 marks)
e) From world renowned scientists, we have heard that a vaccine that acts against this virus can be developed within a year or two. Whereas vaccines for other viruses have taken at least 6 to 10 years to develop. Suggest 2 reasons why it is predicted that a Coronavirus vaccine can be developed in a shorter time frame? (2 marks)