GENETICS PTC LAB EXAM WITH QUESTIONS AND ANSWERS

GENETICS PTC LAB EXAM WITH QUESTIONS AND ANSWERS What is the purpose of the EtNa in the DNA extraction procedure? - ANSWER Causes the cells to lyse so the DNA is released into the solution. Ethanol causes the DNA to precipitate so a pellet is formed separate to the solution List the components that make up a PCR reaction mix and describe their purpose - ANSWER 1. DNA template (has target sequence) 2. DNA polymerase (synthesises new strand) 3. Primers (helps bind polymerase to target sequence) 4. Nucleotides (building blocks for new strands) 5. Coenzyme (magnesium activates enzyme) What are the three steps of the PCR reaction? - ANSWER 1. Denaturing 2. Annealing 3. Elongation What happens during the denaturing step of PCR? - ANSWER Heating the reaction denatures the DNA What happens during the annealing step of PCR? - ANSWER Primers bind, polymerase binds and begins DNA formation What happens during the elongation step of PCR? - ANSWER DNA polymerase synthesises a new complementary DNA strand Why is a single-nucleotide polymorphism? (SNPs) - ANSWER SNP is when a gene has one nucleotide variation among different individuals Explain the potential use of SNPs in predicting drug response - ANSWER Can be used to analyse genes to determine whether an individual will metabolise a drug or not Define haplotype - ANSWER A set of DNA variations that tend to be inherited together - not broken up by recombination What ethical issues are raised by human DNA typing experiments? - ANSWER Privacy, health, income inequality, personal views of knowing that you have a disease, insurance On which chromosome is the TAS2R38 gene? How many bp long is this gene? - ANSWER Chromosome 7, 1002 bp At what position in the gene do the forward and reverse primers bind? - ANSWER Forward primer at the start of the gene at the 5' end - position 98. Reverse primer at the end of the gene at the 3' end - position 297 - 320 What happens to the genomic DNA when it is heated above 65°C and at 95°C? - ANSWER The DNA is denatured What types of food is the phenylthiocarbamide taste sensation associated with? - ANSWER Cruciferous vegetables e.g. broccoli How does the HaeIII enzyme discriminate between the G- C polymorphism in the TAS2R38 gene? - ANSWER HaeIII cuts at the sequence GG:CC which is found at nucleotides 143-146 of the TAS2R38 gene. A non-taster alley changes the sequence at position 145 from a C to a G. This makes the gene no longer recognised by the restriction enzyme. What size products should we expect after the TAS2R38 gene amplicon is digested with this enzyme? - ANSWER 221, 177, 44 for a heterozygous individual What is the definition of one unit of a restriction enzyme? - ANSWER One unit will degrade 1 μg of λ DNA at 37°C for 1 hour