Genetics revision

The DNA is cut into smaller fragments, and cloned into vectors that can later be amplified and read with ease. What role do constructs known as BAC or YAC play in the above illustrated process?

• They are the molecular scissors that help cut the DNA into fragments
• They are used to read the sequences of DNA fragments
• They are the vectors that contain the DNA fragments
• They are hosts like bacteria or yeast, that propagate clones

What of the following provides the best evidence that DNA is the genetic material?

• Presence of DNA in all cells
• Transformation using heat-inactivated bacteria
• Mechanism of semi-conservative DNA replication
• Biomolecular composition of chromosomes

BamHI recognizes 6 base pairs of DNA in a palindromic DNA sequence. If the first part of the sequence is given below, what is the rest of it?

• 5’ CAA 3’
• 5’ GTT 3’
• 5’ AAC 3’
• 5’ TTG 3’

A student adds Taq Polymerase, nucleotides, and primer to a test tube. What procedure are they most likely going to do next?

• Microarray Hybridization Assay
• Gel Electrophoresis
• Polymerase Chain Reaction
• Southern Blot

PCR (polymerase chain reaction) is an excellent method of generating copies of target DNA. If a single piece of double stranded DNA (dsDNA) is put into a PCR machine, how many dsDNA segments will there be after 3 rounds?

• 16 segments, with 2 original strands on different segments
• 16 segments, with the 2 original strands paired
• 8 segments, with the 2 original strands on different segments
• 8 segments, with the 2 original strands paired

A DNA sample was sent off for Sanger sequencing. The results are shown below. What is the sequence of the template strand?

• 5’ TGACAGTCA 3’
• 5’ TGACTGTCA 3’
• 5’ ACTGTCAGT 3’
• 5’ ACTGACAGT 3’

Which procedure is least effective for detecting a specific DNA sequence in a sample?

• Gel Electrophoresis
• Southern Blot
• Polymerase Chain Reaction
• Microarray

A scientist is trying to express gene X in bacteria. After cloning the cDNA from gene X into a plasmid with the appropriate cDNA, and transfecting the plasmid into bacteria the scientist notices that he forgot to add antibiotics. What will greet him the next day?

• A petri dish completely overrun with untransformed and transformed bacteria
• A mostly normal petri dish - antibiotics are just used as a safe-guard against other bacteria
• A petri dish with only untransformed bacteria, the antibiotics are required for transfection
• A petri dish with separate colonies of transformed and untransformed bacteria

The melanocortin-1-receptor (Mc1r) gene helps determine the coat color phenotype in rock pocket mice. A researcher collected DNA from individual rock pocket mice and used DNA sequencing to identify the order of nucleotides in the Mc1r gene for each mouse. A subset of the sequencing data, which shows the results for two mice Figure 1: DNA sequencing data for positions 45-56 of the Mc1r gene in two rock pocket mice. Which of the following can be determined from the data in Figure 1?

• Mouse 1 and Mouse 2 differ in at least one nucleotide of the Mc1r gene.
• Mouse 1 produces a functional Mc1r protein, while Mouse 2 does not
• Mouse 2 is a transgenic organism, while Mouse 1 is not
• Mouse 2 has a longer coat than Mouse 1 does.

A researcher used polymerase chain reaction (PCR) to test four individual diploid nematodes for the presence of a mutation in Gene Y. The researcher designed the reaction so that the DNA fragments amplified from wild type and mutant alleles are 350 and 250 base pairs long, respectively. To identify the genotypes of the individual nematodes, the researcher visualized each PCR result by gel electrophoresis Figure 1. Gel electrophoresis of Gene Y PCRs in nematodes. The first four lanes contain the PCR product from individual nematodes A-D. Lane 5 contains a DNA ladder for size comparison. The size of each band in the ladder is labeled (bp = base pairs). Which of the following claims is best supported by the data shown above?

• Nematode A is homozygous for the mutant allele
• Nematode B is homozygous for the wild type allele
• Nematode C is heterozygous for the mutant allele.
• Nematode D is heterozygous for the mutant allele