Genomic DNA and primers are placed into the PCR machine. Identify two additional substances that are added to the PCR machine, and explain the purpose of each substance.
Gel electrophoresis is performed on the 5 different DNA fragments generated by PCR. Each DNA fragment is placed into a loading well on the gel. The final lane on the electrophoresis gel contains a DNA ladder with DNA lengths that are known. Fig. 5.2 shows the outcomes of the gel electrophoresis. Suggest the role of the DNA ladder.
In the genetic test for MLD, PCR and gel electrophoresis are completed before DNA sequencing. Suggest and explain reasons why PCR and gel electrophoresis are completed before DNA sequencing.
Calculate the number of DNA copies obtained if PCR is run for 35 cycles. Assume that there is only 1 copy of DNA at the beginning of PCR. Give your answer in standard form to two significant figures.
MLD is a rare autosomal recessive disease. It is estimated that there is one case of MLD in every 40 0 births worldwide. Children with MLD have a reduced life expectancy. • MLD is a degenerative disease that causes severe disability. • Before 2022, there was no known cure for MLD and the only treatment for symptoms was to provide pain relief. A new gene therapy treatment known as Libmeldy ae became available in a number of countries in 2022. The treatment must start before symptoms are present. Although the treatment may provide a cure for MLD, a single dose is extremely expensive. Blood samples from newborn babies are screened for a number of rare genetic diseases (neonatal screening) in most countries of the world, but none include screening for MLD. Discuss the social and ethical considerations of including screening for MLD when carrying out neonatal screening in a country where gene therapy for MLD is available.