BIOTECHNOLOGY 2026 CORE EXAM TEST QUESTIONS AND
SOLUTIONS RATED A+
✔✔Describe how a radioactively labeled nucleic acid probe can locate the gene of
interest on a multiwell plate - ✔✔the DNA is denatured in a nylon membrane. The
nucleic acid probe binds to the gene of interest creating a double stranded DNA again.
Then it is laid under photographic film and the radioactive label turns black. From this
the well location of the gene of interest can be determined.
✔✔What are two problems with bacterial gene expression systems? - ✔✔1. gene
expression varies between eukaryotes and prokaryotes, need to insert expression
vector to serve as a promoter to ensure foreign gene is expressed
2. Eukaryotes have introns and this prevents correct expression in bacteria because
they do not have RNA splicing machinery. to solve this, could insert cDNA since it only
has exons.
Or a better solution is usually to use yeast since they are eukaryotic and produce
quickly like bacteria.
✔✔Briefly explain the process of PCR - ✔✔Polymerase Chain Reaction. 1. Heat briefly
to separate strands 2. cool to allow primers to form and hydrogen bonds with ends of
target sequences (annealing stage) 3. DNA polymerase adds nucleotides to the 3' end
of each primer (extension)
✔✔How many molecules will be produced by four PCR cycles? - ✔✔2^n , so 2^4= 16
molecules
✔✔What is gel electrophoresis? - ✔✔a technique used to separate nucleic acids or
proteins that differ in size or electrical charge
✔✔Why is the DNA sample to be separated by gel electrophoresis always loaded at the
cathode/negative end of the power source? - ✔✔DNA has a negative charge and is
repelled by the negative cathode and attracted to the positive anode. When placed at
the negative side, the sample moves towards the positive end, separating the molecule
✔✔Explain why shorter DNA molecules travel farther down the gel than larger
molecules - ✔✔The gel acts as an obstacle course, the agarose fibers impede larger
molecules. The smaller molecules can move more quickly through the gel.
✔✔A patient who is a carrier for sickle cell anemia would have a gel electrophoresis
pattern showing four bands, explain why. - ✔✔The banding pattern depends on how
many times the restriction enzyme can locate the specific sequence that it cuts at. For a
normal patient, there are 3 fragments, for a mutant there are 2. There are four for the
, carrier because it is cut at all the places the mutant AND the normal is cut at . (one
allele of each)
✔✔What is the purpose of a Southern blot? - ✔✔to detect and identify only the genes of
interest on a gel
✔✔What two techniques are used in performing a Southern blot? - ✔✔combines gel
electrophoresis and nucleic acid hybridization
✔✔What was the first technique developed to sequence DNA? -
✔✔dideoxyribonucleotide chain termination method
✔✔Why does a dideoxyribonucleotide terminate a growing DNA strand? - ✔✔It lacks a
3' -OH group which is where the next nucleotide is supposed to attach
✔✔Why are the four nucleotides in DNA each labeled with a different color of
fluorescent for DCTM? - ✔✔so the colors can be used to identify which nucleotide was
added and ultimately sequence the entire DNA strand
✔✔Explain the 4 steps of a DNA microarray assay - ✔✔1. isolate mRNA
2. Make cDNA by reverse transcription using fluorescent tagged nucleotides
3. Apply cDNA mixture to array, cDNA hybridizes with any complimentary DNA on
microarray
4/ Rinse off excess cDNA, scan microarray for fluorescence. Yellow spots indicate that
the gene is expressed in the tissue sample
✔✔Explain how microarrays are used in understanding patterns of gene expression in
normal and cancerous tissue - ✔✔Microarray can be performed on normal cells and
then compared to a microarray of cancer cells, or even done simultaneously. This
allows us to see what proteins cancer cells are expressing that normal cells are not and
vice versa. This gives us an idea of what goes wrong in gene expression in cancer cells
✔✔What is a totipotent cell? - ✔✔any cell with the ability to dedifferentiate and give rise
to all the specialized cell types of the organism. Can be an entire organism. these are
the types of cells the first 4 days after an egg is fertilized
✔✔How is nuclear transplantation performed in animals? - ✔✔The nucleus of an
unfertilized or fertilized egg is removed and replaced with the nucleus of a differentiated
cell
✔✔Explain the six steps in reproductive cloning for mammals - ✔✔1. cultured mammary
cells are semi starved, arresting the cell cycle and causing dedifferentiation.
2. the nucleus of an egg cell is removed
3. the cells are fused together
SOLUTIONS RATED A+
✔✔Describe how a radioactively labeled nucleic acid probe can locate the gene of
interest on a multiwell plate - ✔✔the DNA is denatured in a nylon membrane. The
nucleic acid probe binds to the gene of interest creating a double stranded DNA again.
Then it is laid under photographic film and the radioactive label turns black. From this
the well location of the gene of interest can be determined.
✔✔What are two problems with bacterial gene expression systems? - ✔✔1. gene
expression varies between eukaryotes and prokaryotes, need to insert expression
vector to serve as a promoter to ensure foreign gene is expressed
2. Eukaryotes have introns and this prevents correct expression in bacteria because
they do not have RNA splicing machinery. to solve this, could insert cDNA since it only
has exons.
Or a better solution is usually to use yeast since they are eukaryotic and produce
quickly like bacteria.
✔✔Briefly explain the process of PCR - ✔✔Polymerase Chain Reaction. 1. Heat briefly
to separate strands 2. cool to allow primers to form and hydrogen bonds with ends of
target sequences (annealing stage) 3. DNA polymerase adds nucleotides to the 3' end
of each primer (extension)
✔✔How many molecules will be produced by four PCR cycles? - ✔✔2^n , so 2^4= 16
molecules
✔✔What is gel electrophoresis? - ✔✔a technique used to separate nucleic acids or
proteins that differ in size or electrical charge
✔✔Why is the DNA sample to be separated by gel electrophoresis always loaded at the
cathode/negative end of the power source? - ✔✔DNA has a negative charge and is
repelled by the negative cathode and attracted to the positive anode. When placed at
the negative side, the sample moves towards the positive end, separating the molecule
✔✔Explain why shorter DNA molecules travel farther down the gel than larger
molecules - ✔✔The gel acts as an obstacle course, the agarose fibers impede larger
molecules. The smaller molecules can move more quickly through the gel.
✔✔A patient who is a carrier for sickle cell anemia would have a gel electrophoresis
pattern showing four bands, explain why. - ✔✔The banding pattern depends on how
many times the restriction enzyme can locate the specific sequence that it cuts at. For a
normal patient, there are 3 fragments, for a mutant there are 2. There are four for the
, carrier because it is cut at all the places the mutant AND the normal is cut at . (one
allele of each)
✔✔What is the purpose of a Southern blot? - ✔✔to detect and identify only the genes of
interest on a gel
✔✔What two techniques are used in performing a Southern blot? - ✔✔combines gel
electrophoresis and nucleic acid hybridization
✔✔What was the first technique developed to sequence DNA? -
✔✔dideoxyribonucleotide chain termination method
✔✔Why does a dideoxyribonucleotide terminate a growing DNA strand? - ✔✔It lacks a
3' -OH group which is where the next nucleotide is supposed to attach
✔✔Why are the four nucleotides in DNA each labeled with a different color of
fluorescent for DCTM? - ✔✔so the colors can be used to identify which nucleotide was
added and ultimately sequence the entire DNA strand
✔✔Explain the 4 steps of a DNA microarray assay - ✔✔1. isolate mRNA
2. Make cDNA by reverse transcription using fluorescent tagged nucleotides
3. Apply cDNA mixture to array, cDNA hybridizes with any complimentary DNA on
microarray
4/ Rinse off excess cDNA, scan microarray for fluorescence. Yellow spots indicate that
the gene is expressed in the tissue sample
✔✔Explain how microarrays are used in understanding patterns of gene expression in
normal and cancerous tissue - ✔✔Microarray can be performed on normal cells and
then compared to a microarray of cancer cells, or even done simultaneously. This
allows us to see what proteins cancer cells are expressing that normal cells are not and
vice versa. This gives us an idea of what goes wrong in gene expression in cancer cells
✔✔What is a totipotent cell? - ✔✔any cell with the ability to dedifferentiate and give rise
to all the specialized cell types of the organism. Can be an entire organism. these are
the types of cells the first 4 days after an egg is fertilized
✔✔How is nuclear transplantation performed in animals? - ✔✔The nucleus of an
unfertilized or fertilized egg is removed and replaced with the nucleus of a differentiated
cell
✔✔Explain the six steps in reproductive cloning for mammals - ✔✔1. cultured mammary
cells are semi starved, arresting the cell cycle and causing dedifferentiation.
2. the nucleus of an egg cell is removed
3. the cells are fused together
