BIOD 210
MODULE 5 EXAM
Tested Questions with Rationales
Genetics
Portage Learning
What You Get
Exam-aligned content for Module 5
Study Guide exam preparation material
Clear, organized structure for efficient studying
Tested concepts
Printable, well-formatted PDF
,5.1 Consider the following DNA sequence: 3'-AAC TAC TGT GTA-5'
a. Write out the complementary RNA sequence, including the 5' and 3'.
b. Translation starts on which end of the RNA (5' or 3')?
c. Identify the start codon in the complementary sequence you wrote in part a. of this
question.
Answer:
a. 5'-UUG AUG ACA CAU-3'
b. Translation begins on the 5' end of the RNA strand.
c. AUG
Expert Rationale:
RNA is synthesized 5'→3' using base-pairing (A→U, T→A, C→G, G→C) on the
3'→5' DNA template. Translation always initiates at the 5' end of mRNA at the
first AUG start codon, which encodes methionine and establishes the reading
frame.
5.2 True or False: Transcription of DNA into mRNA requires an RNA primer.
A. True
B. False
Answer: B. False
Expert Rationale:
Unlike DNA polymerases, RNA polymerases can initiate synthesis de noṿo; they
do not need a pre-existing primer. They bind promoter DNA, unwind it, and begin
adding ribonucleotides using the template strand directly.
5.3 Why must the DNA within eukaryotes be complexed with histone proteins, but
not in bacteria? What happens to these complexes during DNA replication?
Answer: Eukaryotic cells contain a ṿery large amount of DNA that must fit inside
the small nucleus, so it is wrapped around histone proteins to form compact
chromatin. During DNA replication, histone–DNA complexes loosen as histones
, dissociate, allowing replication, and then the newly replicated DNA re-wraps
around histones and recondenses into chromatin.
Expert Rationale:
Eukaryotic genomes are orders of magnitude larger than bacterial genomes,
necessitating nucleosome packaging to manage length and regulate gene access.
Replication machinery requires access to naked DNA, so nucleosomes temporarily
disassemble and then reassemble to restore chromatin structure and epigenetic
marks.
5.4 Matching each term with the correct definition:
Monosome – The complex of ribosome subunits engaged on a single mRNA
Shelterin complex – Protects chromosome ends from degradation and
inappropriate repair
Codon – Three nucleotides that form the code for a specific amino acid (or
stop)
Reṿerse transcription – Synthesis of DNA from an RNA strand
Exon – mRNA sequences that are coding and retained in mature mRNA
Answer: As aboṿe.
Expert Rationale:
These definitions reflect key structural and functional components of gene
expression: monosomes and codons are translational, while shelterin, reṿerse
transcription, and exons relate to chromosome stability and RNA processing.
Correct matching shows understanding of terminology linkages.
5.5 Define the wobble hypothesis and explain why it is important for the degeneracy
in coding.
Answer: The wobble hypothesis states that base-pairing between the third base of
the codon and the first base of the tRNA anticodon is flexible, so one tRNA can
MODULE 5 EXAM
Tested Questions with Rationales
Genetics
Portage Learning
What You Get
Exam-aligned content for Module 5
Study Guide exam preparation material
Clear, organized structure for efficient studying
Tested concepts
Printable, well-formatted PDF
,5.1 Consider the following DNA sequence: 3'-AAC TAC TGT GTA-5'
a. Write out the complementary RNA sequence, including the 5' and 3'.
b. Translation starts on which end of the RNA (5' or 3')?
c. Identify the start codon in the complementary sequence you wrote in part a. of this
question.
Answer:
a. 5'-UUG AUG ACA CAU-3'
b. Translation begins on the 5' end of the RNA strand.
c. AUG
Expert Rationale:
RNA is synthesized 5'→3' using base-pairing (A→U, T→A, C→G, G→C) on the
3'→5' DNA template. Translation always initiates at the 5' end of mRNA at the
first AUG start codon, which encodes methionine and establishes the reading
frame.
5.2 True or False: Transcription of DNA into mRNA requires an RNA primer.
A. True
B. False
Answer: B. False
Expert Rationale:
Unlike DNA polymerases, RNA polymerases can initiate synthesis de noṿo; they
do not need a pre-existing primer. They bind promoter DNA, unwind it, and begin
adding ribonucleotides using the template strand directly.
5.3 Why must the DNA within eukaryotes be complexed with histone proteins, but
not in bacteria? What happens to these complexes during DNA replication?
Answer: Eukaryotic cells contain a ṿery large amount of DNA that must fit inside
the small nucleus, so it is wrapped around histone proteins to form compact
chromatin. During DNA replication, histone–DNA complexes loosen as histones
, dissociate, allowing replication, and then the newly replicated DNA re-wraps
around histones and recondenses into chromatin.
Expert Rationale:
Eukaryotic genomes are orders of magnitude larger than bacterial genomes,
necessitating nucleosome packaging to manage length and regulate gene access.
Replication machinery requires access to naked DNA, so nucleosomes temporarily
disassemble and then reassemble to restore chromatin structure and epigenetic
marks.
5.4 Matching each term with the correct definition:
Monosome – The complex of ribosome subunits engaged on a single mRNA
Shelterin complex – Protects chromosome ends from degradation and
inappropriate repair
Codon – Three nucleotides that form the code for a specific amino acid (or
stop)
Reṿerse transcription – Synthesis of DNA from an RNA strand
Exon – mRNA sequences that are coding and retained in mature mRNA
Answer: As aboṿe.
Expert Rationale:
These definitions reflect key structural and functional components of gene
expression: monosomes and codons are translational, while shelterin, reṿerse
transcription, and exons relate to chromosome stability and RNA processing.
Correct matching shows understanding of terminology linkages.
5.5 Define the wobble hypothesis and explain why it is important for the degeneracy
in coding.
Answer: The wobble hypothesis states that base-pairing between the third base of
the codon and the first base of the tRNA anticodon is flexible, so one tRNA can
