BCHM 4360 Exam A+ Questions and
Answers Verified Solutions Latest Update
2026/2027
Question:
Double-strand Break (DSB).
Answer:
A break in both strands of DNA requiring repair to maintain genome stability
Question:
End resection.
Answer:
Degradation of 5' DNA ends to create 3' single-stranded overhangs during HR.
Question:
3' Overhang.
Answer:
Single-stranded DNA used to invade homologous DNA during recombination.
Question:
Strand invasion.
Answer:
Process where ssDNA pairs with homologous duplex DNA to initiate repair
Question:
D-loop.
,Answer:
Displacement loop formed when invading DNA strand pairs with homologous template.
Question:
Rad51.
Answer:
Eukaryotic protein that mediates strand invasion during homologous recombination.
Question:
RecA.
Answer:
Bacterial homologous of Rad51 that promotes homologous recombination.
Question:
Holiday junction.
Answer:
Cross-shaped DNA structure formed during homologous recombination.
Question:
Crossover recombination.
Answer:
Exchange of genetic material between DNA molecules after Holliday junction resolution.
Question:
Non-crossover recombination.
Answer:
Repair without exchange of chromosome arms.
,Question:
Homologous recombination vs NHEJ.
Answer:
HR uses template and is accurate; NHEJ directly legates DNA and is error-prone
Question:
CRISPR.
Answer:
Cluster Regularly Interspaced Short Palindromic Repeats forming bacterial adaptive immunity.
Question:
Cas9.
Answer:
RNA-guided endonuclease that creates double strand DNA breaks.
Question:
Guide RNA (gRNA).
Answer:
RNA molecule directing Cas9 to a specific DNA sequence.
Question:
crRNA.
Answer:
RNA containing target sequence information.
Question:
TracrRNA.
Answer:
, RNA that binds Cas9 and stabilizes crRNA.
Question:
PAM sequence.
Answer:
Short DNA motif required for Cas9 binding and cleavage (e.g., NGG).
Question:
CRISPR double-strand break outcome.
Answer:
Determined by cellular repair pathway, not Cas9 itself
Question:
NHEJ repair.
Answer:
Error-prone repair causing insertions or deletions (gene knockout)
Question:
HDR (homology-directed repair).
Answer:
Precise repair using donor template for gene editing.
Question:
Gene knockout.
Answer:
Loss of gene function typically caused by NHEJ indels.
Question:
Answers Verified Solutions Latest Update
2026/2027
Question:
Double-strand Break (DSB).
Answer:
A break in both strands of DNA requiring repair to maintain genome stability
Question:
End resection.
Answer:
Degradation of 5' DNA ends to create 3' single-stranded overhangs during HR.
Question:
3' Overhang.
Answer:
Single-stranded DNA used to invade homologous DNA during recombination.
Question:
Strand invasion.
Answer:
Process where ssDNA pairs with homologous duplex DNA to initiate repair
Question:
D-loop.
,Answer:
Displacement loop formed when invading DNA strand pairs with homologous template.
Question:
Rad51.
Answer:
Eukaryotic protein that mediates strand invasion during homologous recombination.
Question:
RecA.
Answer:
Bacterial homologous of Rad51 that promotes homologous recombination.
Question:
Holiday junction.
Answer:
Cross-shaped DNA structure formed during homologous recombination.
Question:
Crossover recombination.
Answer:
Exchange of genetic material between DNA molecules after Holliday junction resolution.
Question:
Non-crossover recombination.
Answer:
Repair without exchange of chromosome arms.
,Question:
Homologous recombination vs NHEJ.
Answer:
HR uses template and is accurate; NHEJ directly legates DNA and is error-prone
Question:
CRISPR.
Answer:
Cluster Regularly Interspaced Short Palindromic Repeats forming bacterial adaptive immunity.
Question:
Cas9.
Answer:
RNA-guided endonuclease that creates double strand DNA breaks.
Question:
Guide RNA (gRNA).
Answer:
RNA molecule directing Cas9 to a specific DNA sequence.
Question:
crRNA.
Answer:
RNA containing target sequence information.
Question:
TracrRNA.
Answer:
, RNA that binds Cas9 and stabilizes crRNA.
Question:
PAM sequence.
Answer:
Short DNA motif required for Cas9 binding and cleavage (e.g., NGG).
Question:
CRISPR double-strand break outcome.
Answer:
Determined by cellular repair pathway, not Cas9 itself
Question:
NHEJ repair.
Answer:
Error-prone repair causing insertions or deletions (gene knockout)
Question:
HDR (homology-directed repair).
Answer:
Precise repair using donor template for gene editing.
Question:
Gene knockout.
Answer:
Loss of gene function typically caused by NHEJ indels.
Question:
