Genetics PTC Lab UPDATED ACTUAL
Exam Questions and CORRECT Answers
What is the purpose of the EtNa in the DNA extraction procedure? - CORRECT
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 - CORRECT
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? - CORRECT ANSWER - 1. Denaturing 2.
Annealing 3. Elongation
What happens during the denaturing step of PCR? - CORRECT ANSWER - Heating the
reaction denatures the DNA
What happens during the annealing step of PCR? - CORRECT ANSWER - Primers bind,
polymerase binds and begins DNA formation
What happens during the elongation step of PCR? - CORRECT ANSWER - DNA
polymerase synthesises a new complementary DNA strand
Why is a single-nucleotide polymorphism? (SNPs) - CORRECT ANSWER - SNP is when
a gene has one nucleotide variation among different individuals
Explain the potential use of SNPs in predicting drug response - CORRECT ANSWER -
Can be used to analyse genes to determine whether an individual will metabolise a drug or not
Define haplotype - CORRECT 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? - CORRECT
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? - CORRECT
ANSWER - Chromosome 7, 1002 bp
At what position in the gene do the forward and reverse primers bind? - CORRECT
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? - CORRECT
ANSWER - The DNA is denatured
What types of food is the phenylthiocarbamide taste sensation associated with? - CORRECT
ANSWER - Cruciferous vegetables e.g. broccoli
How does the HaeIII enzyme discriminate between the G-C polymorphism in the TAS2R38
gene? - CORRECT 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? - CORRECT ANSWER - 221, 177, 44 for a heterozygous individual
What is the definition of one unit of a restriction enzyme? - CORRECT ANSWER - One
unit will degrade 1 μg of λ DNA at 37°C for 1 hour
What is a synonymous mutation? - CORRECT ANSWER - A synonymous mutation is a
change in one base pair that still codes for the same animo acid as the wild-type allele.
Exam Questions and CORRECT Answers
What is the purpose of the EtNa in the DNA extraction procedure? - CORRECT
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 - CORRECT
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? - CORRECT ANSWER - 1. Denaturing 2.
Annealing 3. Elongation
What happens during the denaturing step of PCR? - CORRECT ANSWER - Heating the
reaction denatures the DNA
What happens during the annealing step of PCR? - CORRECT ANSWER - Primers bind,
polymerase binds and begins DNA formation
What happens during the elongation step of PCR? - CORRECT ANSWER - DNA
polymerase synthesises a new complementary DNA strand
Why is a single-nucleotide polymorphism? (SNPs) - CORRECT ANSWER - SNP is when
a gene has one nucleotide variation among different individuals
Explain the potential use of SNPs in predicting drug response - CORRECT ANSWER -
Can be used to analyse genes to determine whether an individual will metabolise a drug or not
Define haplotype - CORRECT 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? - CORRECT
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? - CORRECT
ANSWER - Chromosome 7, 1002 bp
At what position in the gene do the forward and reverse primers bind? - CORRECT
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? - CORRECT
ANSWER - The DNA is denatured
What types of food is the phenylthiocarbamide taste sensation associated with? - CORRECT
ANSWER - Cruciferous vegetables e.g. broccoli
How does the HaeIII enzyme discriminate between the G-C polymorphism in the TAS2R38
gene? - CORRECT 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? - CORRECT ANSWER - 221, 177, 44 for a heterozygous individual
What is the definition of one unit of a restriction enzyme? - CORRECT ANSWER - One
unit will degrade 1 μg of λ DNA at 37°C for 1 hour
What is a synonymous mutation? - CORRECT ANSWER - A synonymous mutation is a
change in one base pair that still codes for the same animo acid as the wild-type allele.
