BIOC 385 EXAM 4 QUESTIONS AND ANSWERS SOLVED CORRECTLY LATEST UPDATE 2025-
2026
Which statement is the most correct regarding the trombone model of DNA synthesis? -
Answers The lagging strand template is released by Pol III when it reaches the 5' end of the RNA
primer.
Use the 9 nucleotide DNA base pairs below to determine the mRNA and protein sequences.
5' CCA TAC CGG 3'
3' GGT ATG GCC 5' - Answers mRNA 5' CCA UAC CGG 3'
The amino acid sequence is Pro-Tyr-Arg
What is the different between models for semiconservative and dispersive DNA replication? -
Answers Semiconservative replication yields two DNA molecules where each contains one
template strand and one new DNA strand; dispersive replication yields two DNA molecules that
both mixed DNA.
What is the main purpose of the Ames test? - Answers To determine if chemicals mutate DNA
by quantifying their effort on reverting a His- phenotype.
Which statement is most correct regarding the function of a) mRNA and b) rRNA? - Answers
mRNA is the carrier of genetic information, b) rRNA is the major RNA constituent of ribosomes.
Number the steps from start of RNA synthesis to start of protein synthesis in eukaryotes. -
Answers 1. RNA Pol II CTD is hyperphosphorylate by TFIIH
2. Guanine-N7-methyltransferase adds the m7G cap.
3. U1/U2 form a complex at the 5' end of introns.
4. U6/U5/U2 complex cleaves the 3' end of introns.
5. CStF protein binds to AAUAAA sequence at 3' end.
6. Poly(A) polymerase adds 200 adenine residues.
7. mRNA is exported through the nuclear pore complex.
Which statement is most correct regarding characteristics of codons in the genetic code? -
Answers Genetic code is 64 codons with 61 corresponding to the 20 amino acids and 3 that are
stop codons.
Number the steps from start to finish for prokaryotic mRNA translation. - Answers 1. Initiation
, factors (IFs) bind to the 30S ribosome along with GTP.
2. mRNA, Shine-Dalgarno sequence base-pairs with 16S rRNA in 30S subunit.
3. Binding og 50S subunit, GTP hydrolysis, release of IFs, 70S ribosome forms.
4. Translational elongation proceeds in the 3' direction along the mRNA strand.
5. Stop codon enters A site, binding to RF protein, disassembly of ribosome.
What accounts for the accuracy of DNA synthesis at the replication fork? - Answers
Proofreading function of DNA polymerase that removes incorrect nucleotides in 3' to 5' direction.
In the wobble position, inosine binds to adenine, cytosine, and uracil, but not guanine. Why not? -
Answers Inosine and guanine are chemically incompatible to form hydrogen bonds.
What is the BEST explanation for why there is redundancy in the genetic code? - Answers tRNA
wobble position at 5' position of tRNA anticodon and 3' position of mRNA codon allows non
canonical base pairing to occur.
Which component of eukaryotic mRNA are removed by RNA processing? - Answers Intronic
sequences.
DNA replication is _____ which requires that _____ unwinds the DNA double helix. - Answers
conservative; helicase
Next, _____ binds and forms the replisome and moves along the template strand in a _____. -
Answers DNA Pol III; 5' to 3' direction
If a mistake is made on the newly synthesized DNA, DNA Pol III corrects the error in a _____. -
Answers 3' to 5' direction
After DNA replication is complete, the double stranded DNA is a _____-handed DNA helix. -
Answers right
When the signal recognition particle (SRP) binds to the endoplasmic reticulum (ER) signal
peptide sequence on the amino terminal end of the polypeptide in the early stages of translation,
the ribosome pauses on the mRNA and stops translation. What is the purpose of this ribosome
pausing? - Answers Allows time for the SRP-Ribosome complex to bind the SRP receptor.
A ribozyme is an RNA enzyme that functions as a catalyst to mediate substrate reactions.
Which is true regarding ribozyme-mediated cleavage? - Answers The ribozyme reaction involves
a phosphodiester cleavage through acid-base and metal ion catalysis.
What is the type of molecular defect that has been linked to the disease retinitis pigmentosa? -
Answers Mutation in a splicing protein causing defects in the spliceosome machinery.
2026
Which statement is the most correct regarding the trombone model of DNA synthesis? -
Answers The lagging strand template is released by Pol III when it reaches the 5' end of the RNA
primer.
Use the 9 nucleotide DNA base pairs below to determine the mRNA and protein sequences.
5' CCA TAC CGG 3'
3' GGT ATG GCC 5' - Answers mRNA 5' CCA UAC CGG 3'
The amino acid sequence is Pro-Tyr-Arg
What is the different between models for semiconservative and dispersive DNA replication? -
Answers Semiconservative replication yields two DNA molecules where each contains one
template strand and one new DNA strand; dispersive replication yields two DNA molecules that
both mixed DNA.
What is the main purpose of the Ames test? - Answers To determine if chemicals mutate DNA
by quantifying their effort on reverting a His- phenotype.
Which statement is most correct regarding the function of a) mRNA and b) rRNA? - Answers
mRNA is the carrier of genetic information, b) rRNA is the major RNA constituent of ribosomes.
Number the steps from start of RNA synthesis to start of protein synthesis in eukaryotes. -
Answers 1. RNA Pol II CTD is hyperphosphorylate by TFIIH
2. Guanine-N7-methyltransferase adds the m7G cap.
3. U1/U2 form a complex at the 5' end of introns.
4. U6/U5/U2 complex cleaves the 3' end of introns.
5. CStF protein binds to AAUAAA sequence at 3' end.
6. Poly(A) polymerase adds 200 adenine residues.
7. mRNA is exported through the nuclear pore complex.
Which statement is most correct regarding characteristics of codons in the genetic code? -
Answers Genetic code is 64 codons with 61 corresponding to the 20 amino acids and 3 that are
stop codons.
Number the steps from start to finish for prokaryotic mRNA translation. - Answers 1. Initiation
, factors (IFs) bind to the 30S ribosome along with GTP.
2. mRNA, Shine-Dalgarno sequence base-pairs with 16S rRNA in 30S subunit.
3. Binding og 50S subunit, GTP hydrolysis, release of IFs, 70S ribosome forms.
4. Translational elongation proceeds in the 3' direction along the mRNA strand.
5. Stop codon enters A site, binding to RF protein, disassembly of ribosome.
What accounts for the accuracy of DNA synthesis at the replication fork? - Answers
Proofreading function of DNA polymerase that removes incorrect nucleotides in 3' to 5' direction.
In the wobble position, inosine binds to adenine, cytosine, and uracil, but not guanine. Why not? -
Answers Inosine and guanine are chemically incompatible to form hydrogen bonds.
What is the BEST explanation for why there is redundancy in the genetic code? - Answers tRNA
wobble position at 5' position of tRNA anticodon and 3' position of mRNA codon allows non
canonical base pairing to occur.
Which component of eukaryotic mRNA are removed by RNA processing? - Answers Intronic
sequences.
DNA replication is _____ which requires that _____ unwinds the DNA double helix. - Answers
conservative; helicase
Next, _____ binds and forms the replisome and moves along the template strand in a _____. -
Answers DNA Pol III; 5' to 3' direction
If a mistake is made on the newly synthesized DNA, DNA Pol III corrects the error in a _____. -
Answers 3' to 5' direction
After DNA replication is complete, the double stranded DNA is a _____-handed DNA helix. -
Answers right
When the signal recognition particle (SRP) binds to the endoplasmic reticulum (ER) signal
peptide sequence on the amino terminal end of the polypeptide in the early stages of translation,
the ribosome pauses on the mRNA and stops translation. What is the purpose of this ribosome
pausing? - Answers Allows time for the SRP-Ribosome complex to bind the SRP receptor.
A ribozyme is an RNA enzyme that functions as a catalyst to mediate substrate reactions.
Which is true regarding ribozyme-mediated cleavage? - Answers The ribozyme reaction involves
a phosphodiester cleavage through acid-base and metal ion catalysis.
What is the type of molecular defect that has been linked to the disease retinitis pigmentosa? -
Answers Mutation in a splicing protein causing defects in the spliceosome machinery.
