BIMM 100 midterm 2 questions
correctly answered already passed
Question 1: How is Electrophoretic Mobility Shift Assay (EMSA) adapted for analyzing multiple
proteins binding to a single DNA probe? - correct answer ✔✔ Electrophoretic Mobility Shift
Assay (EMSA) is a technique used to study protein-DNA interactions by observing the mobility of
DNA-protein complexes during electrophoresis. To analyze multiple proteins binding to a single
DNA probe, a labeled DNA probe and purified proteins are prepared. The DNA is incubated with
each protein individually and in combination under optimal binding conditions. Samples are
then loaded onto a non-denaturing polyacrylamide gel for electrophoresis, which separates the
complexes based on size and charge. DNA-protein complexes migrate more slowly than free
DNA, resulting in a position shift. The gel is analyzed using autoradiography or fluorescence
imaging, with each protein-DNA complex showing a distinct mobility shift. A supershift assay,
using specific antibodies against one of the proteins, further distinguishes the proteins by
causing an even slower migration of the antibody-protein-DNA complex. This adapted EMSA
technique allows for the determination of which proteins are binding to the DNA probe and
provides insights into their binding characteristics.
Question 2: How do you identify a mutation in a sequence of wild-type and mutant RNA,
specifically a single base mutation? - correct answer ✔✔ To identify a single base mutation in a
sequence of wild-type and mutant RNA, one would first compare the sequences to locate the
exact position of the base change. For instance, if the mutation occurs at the start codon, the
altered RNA sequence and the wild-type sequence may still encode the same amino acid due to
the redundancy in the genetic code. This specific type of mutation is known as a silent mutation
because, despite the change in the nucleotide sequence, the resulting protein remains
unchanged. Consequently, the mutation does not affect the protein's structure or function.
Identifying such mutations involves analyzing the RNA sequences and their corresponding
codons, ensuring that the encoded amino acids remain the same. Silent mutations often occur
in the third position of a codon, where changes are less likely to alter the amino acid being
coded.
Question 3: How does inhibiting transcription factors affect transcription in eukaryotic and
prokaryotic systems differently when trying to transcribe a certain cancer gene? - correct
answer ✔✔ When attempting to transcribe a cancer gene, the effects of inhibiting transcription
factors differ between eukaryotic and prokaryotic systems due to the distinct mechanisms each
correctly answered already passed
Question 1: How is Electrophoretic Mobility Shift Assay (EMSA) adapted for analyzing multiple
proteins binding to a single DNA probe? - correct answer ✔✔ Electrophoretic Mobility Shift
Assay (EMSA) is a technique used to study protein-DNA interactions by observing the mobility of
DNA-protein complexes during electrophoresis. To analyze multiple proteins binding to a single
DNA probe, a labeled DNA probe and purified proteins are prepared. The DNA is incubated with
each protein individually and in combination under optimal binding conditions. Samples are
then loaded onto a non-denaturing polyacrylamide gel for electrophoresis, which separates the
complexes based on size and charge. DNA-protein complexes migrate more slowly than free
DNA, resulting in a position shift. The gel is analyzed using autoradiography or fluorescence
imaging, with each protein-DNA complex showing a distinct mobility shift. A supershift assay,
using specific antibodies against one of the proteins, further distinguishes the proteins by
causing an even slower migration of the antibody-protein-DNA complex. This adapted EMSA
technique allows for the determination of which proteins are binding to the DNA probe and
provides insights into their binding characteristics.
Question 2: How do you identify a mutation in a sequence of wild-type and mutant RNA,
specifically a single base mutation? - correct answer ✔✔ To identify a single base mutation in a
sequence of wild-type and mutant RNA, one would first compare the sequences to locate the
exact position of the base change. For instance, if the mutation occurs at the start codon, the
altered RNA sequence and the wild-type sequence may still encode the same amino acid due to
the redundancy in the genetic code. This specific type of mutation is known as a silent mutation
because, despite the change in the nucleotide sequence, the resulting protein remains
unchanged. Consequently, the mutation does not affect the protein's structure or function.
Identifying such mutations involves analyzing the RNA sequences and their corresponding
codons, ensuring that the encoded amino acids remain the same. Silent mutations often occur
in the third position of a codon, where changes are less likely to alter the amino acid being
coded.
Question 3: How does inhibiting transcription factors affect transcription in eukaryotic and
prokaryotic systems differently when trying to transcribe a certain cancer gene? - correct
answer ✔✔ When attempting to transcribe a cancer gene, the effects of inhibiting transcription
factors differ between eukaryotic and prokaryotic systems due to the distinct mechanisms each
