BIO 400 EXAM 4 QUESTIONS AND ANSWERS
In vivo gene therapy - CORRECT ANSWER✅✅Delivery of nucleic acid or vector directly into the patient,
where target cells are modified inside the body.
Ex vivo gene therapy - CORRECT ANSWER✅✅Patient cells are removed, genetically modified in culture,
and then returned to the patient.
How antisense cDNA/RNA suppresses gene expression - CORRECT ANSWER✅✅A reverse-orientation
cDNA is cloned, producing antisense RNA that hybridizes to mRNA, blocking translation and promoting
RNA degradation.
IGF-1 antisense example - CORRECT ANSWER✅✅Antisense RNA reduces IGF-1 signaling, decreasing
tumor cell proliferation.
Antisense oligonucleotides (ASOs) - CORRECT ANSWER✅✅Short synthetic DNA strands (15-24 bases)
that bind mRNA and recruit RNase H for mRNA degradation.
Mechanism of mipomersen - CORRECT ANSWER✅✅ASO that binds apolipoprotein B-100 mRNA; RNase
H degrades the mRNA, lowering ApoB and reducing LDL cholesterol.
Why phosphorothioate oligos are more stable - CORRECT ANSWER✅✅Sulfur substitution in the
backbone makes them resistant to nucleases compared to phosphodiester linkages.
Interfering RNA (RNAi) - CORRECT ANSWER✅✅Double-stranded RNA processed into siRNA, which
directs sequence-specific mRNA degradation and reduces target protein expression.
Effect of siRNA on gene expression - CORRECT ANSWER✅✅Silences genes by reducing target mRNA
levels by up to ~90%.
Role of Dicer - CORRECT ANSWER✅✅RNase III enzyme that cuts dsRNA into 21-23 nt siRNAs.
, Role of Argonaute - CORRECT ANSWER✅✅Part of RISC; binds siRNA and cleaves complementary target
mRNA.
Hereditary transthyretin amyloidosis (hATTR) - CORRECT ANSWER✅✅Disease caused by mutant TTR
forming amyloid deposits; leads to neuropathy and autonomic dysfunction.
Function of transthyretin (TTR) - CORRECT ANSWER✅✅Transports thyroxine (T4) and retinol in serum
and cerebrospinal fluid.
Patisiran treatment - CORRECT ANSWER✅✅siRNA therapy delivering RNA to the liver every 3 weeks to
reduce TTR production.
Huntington's disease cause - CORRECT ANSWER✅✅Expanded CAG repeats in the HTT gene.
RNAi therapy for Huntington's disease - CORRECT ANSWER✅✅siRNA or shRNA selectively silences
mutant HTT in neurons (in vivo).
Non-viral delivery: direct injection - CORRECT ANSWER✅✅Nucleic acids delivered via local or
intravenous injection.
Non-viral delivery: liposomes/LNPs - CORRECT ANSWER✅✅siRNA or DNA packaged into lipid
nanoparticles for cellular uptake.
Non-viral delivery: chemical conjugation - CORRECT ANSWER✅✅Nucleic acids linked to ligands or
polymers to enhance targeting and uptake.
Cholesterol-conjugated siRNA - CORRECT ANSWER✅✅siRNA chemically linked to cholesterol to
improve uptake into tissues via lipoprotein pathways.
How cholesterol aids delivery - CORRECT ANSWER✅✅Interacts with membranes and promotes uptake
through lipoprotein nanoparticles, especially targeting liver tissue
In vivo gene therapy - CORRECT ANSWER✅✅Delivery of nucleic acid or vector directly into the patient,
where target cells are modified inside the body.
Ex vivo gene therapy - CORRECT ANSWER✅✅Patient cells are removed, genetically modified in culture,
and then returned to the patient.
How antisense cDNA/RNA suppresses gene expression - CORRECT ANSWER✅✅A reverse-orientation
cDNA is cloned, producing antisense RNA that hybridizes to mRNA, blocking translation and promoting
RNA degradation.
IGF-1 antisense example - CORRECT ANSWER✅✅Antisense RNA reduces IGF-1 signaling, decreasing
tumor cell proliferation.
Antisense oligonucleotides (ASOs) - CORRECT ANSWER✅✅Short synthetic DNA strands (15-24 bases)
that bind mRNA and recruit RNase H for mRNA degradation.
Mechanism of mipomersen - CORRECT ANSWER✅✅ASO that binds apolipoprotein B-100 mRNA; RNase
H degrades the mRNA, lowering ApoB and reducing LDL cholesterol.
Why phosphorothioate oligos are more stable - CORRECT ANSWER✅✅Sulfur substitution in the
backbone makes them resistant to nucleases compared to phosphodiester linkages.
Interfering RNA (RNAi) - CORRECT ANSWER✅✅Double-stranded RNA processed into siRNA, which
directs sequence-specific mRNA degradation and reduces target protein expression.
Effect of siRNA on gene expression - CORRECT ANSWER✅✅Silences genes by reducing target mRNA
levels by up to ~90%.
Role of Dicer - CORRECT ANSWER✅✅RNase III enzyme that cuts dsRNA into 21-23 nt siRNAs.
, Role of Argonaute - CORRECT ANSWER✅✅Part of RISC; binds siRNA and cleaves complementary target
mRNA.
Hereditary transthyretin amyloidosis (hATTR) - CORRECT ANSWER✅✅Disease caused by mutant TTR
forming amyloid deposits; leads to neuropathy and autonomic dysfunction.
Function of transthyretin (TTR) - CORRECT ANSWER✅✅Transports thyroxine (T4) and retinol in serum
and cerebrospinal fluid.
Patisiran treatment - CORRECT ANSWER✅✅siRNA therapy delivering RNA to the liver every 3 weeks to
reduce TTR production.
Huntington's disease cause - CORRECT ANSWER✅✅Expanded CAG repeats in the HTT gene.
RNAi therapy for Huntington's disease - CORRECT ANSWER✅✅siRNA or shRNA selectively silences
mutant HTT in neurons (in vivo).
Non-viral delivery: direct injection - CORRECT ANSWER✅✅Nucleic acids delivered via local or
intravenous injection.
Non-viral delivery: liposomes/LNPs - CORRECT ANSWER✅✅siRNA or DNA packaged into lipid
nanoparticles for cellular uptake.
Non-viral delivery: chemical conjugation - CORRECT ANSWER✅✅Nucleic acids linked to ligands or
polymers to enhance targeting and uptake.
Cholesterol-conjugated siRNA - CORRECT ANSWER✅✅siRNA chemically linked to cholesterol to
improve uptake into tissues via lipoprotein pathways.
How cholesterol aids delivery - CORRECT ANSWER✅✅Interacts with membranes and promotes uptake
through lipoprotein nanoparticles, especially targeting liver tissue
