DNA based diagnostics

Question 1

Steps for nucleic acid hybridisation/ PCR

Answer 1

• A single strand of DNA can pair specifically with a second strand of complementary nucleotide sequence
• Two strands of double helix, held together by H bonds, can be separated by heating to about 90oC (or by extremes of pH)
• Does not break phosphodiester bonds between sugars and phosphates If temperature is slowly lowered, the complementary strands will re-form double helices = hybridisation or renaturation

Question 2

Current uses of genetic testing

Answer 2

• To confirm the diagnosis of a genetic disease
• To test for carrier status
• Prenatal testing/screening
• Routine neonatal screening (phenylketonuria, congenital hypothyroidism, cystic fibrosis and sickle cell disorders)
• Predictive and susceptibility testing
• Paternity tests
• Forensics
• Pharmacogenetic testing
• Genotyping of pathogens