Colour blindness is a sex linked recessive disease that means the progeny, if it is a girl, both the father and the mother to be a carrier. However if the father was a carrier, he’d be colour-blind as well since males have only one X chromosome. Therefore, the colour-blind child born was male. If both parents were normal, this means that the mother was a carrier.
Thalassemia ia an autosomal recessive disorder. For the child to have the disorder, both parents need to have been a carrier of the faulty gene.
a) Hershey and Chase carried out their experiments to figure out if it was indeed DNA that was the genetic material.
b) i) They used P32 and S35. The radioactive isotope of phosphorous was used to label DNA and the radioactive isotope of sulphur was used to label the protein capsule of the bacteriophage.
ii) The culture needed to be spun and agitated so as to remove the virus coat from bacteria.
• S35 was detected in the supernatant.
• Radioactive P32 was detected in the cell.
• The proteins did not enter the bacteria from the viruses therefore it was concluded that DNA is the genetic material that got passed from the virus to the bacteria.
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