Question

You have been asked to generate a kit to assay for the presence of a novel coroma virus that has a DNA genome. You plan to base the kit on the polymerase chain reaction, so it should contain  

Select one:

a. a thermostable polymerase, RNA primers to a unique region of the virus and an RNA template from the patient

b. a thermostable ligase, RNA primers to a region common to all coroma viruses and a DNA template from the patient

c. a thermostable polymerase, DNA primers to a unique region of the virus and an RNA template from the patient

d. a thermostable polymerase, DNA primers to a unique region of the virus and a DNA template from the patient

e. a thermostable polymerase, DNA primers for a region common to all coroma viruses and a DNA template from the patient

Anticancer drugs target many different aspects of cellular function.  Drugs like Herceptin can treat some breast cancers because

Select one:

a. they enhance cellular immunity by stimulating antibody production

b. they block a signaling process

c. they remove toxins from the body

d. they inactivate the Ras protein

e. they stimulate DNA repair

The inactivated X chromosome is a dark-staining feature called a Barr body in the nuclei of female mammals. How many Barr bodies would be present in nuclei from an individual of karyotype 48, XXYY?

Select one:

a. 1

b. 3

c. 0

d. 2

e. 4

Answer 1

1. Answer is (e) PCR always use the thermostable polymerase so that it can act on and amplify the specific region of the viral DNA. The action of the DNA primer is at a particular sequence not in all region. As the genetic material of the Corona virus is DNA, there is no need for amplification using the RNA. In PCR, if the virus has RNA as genetic material, it need to be modified to DNA for the amplification process. The suspect individual's DNA should be collected for the detection.

2. Answer is (b) Herceptin can be used to treat the breast cancer because it attaches itself to the HER2 receptors on the surface of the cancer cells and block them from receiving the signal. Thus the growth of the cancerous cells can be slowed down or stopped.

3. Answer is (a) The number of Barr bodies present in the individual corresponds to "one less chromosome from the total number of X- chromosomes". There is total of two X chromosomes.Thus the total number of Barr bodies= 2-1= 1