ASCP Molecular Biology Certification
Exam (2025) Exam Questions & Answers
| Latest Already Graded A+ UPDATE
2025|2026
Pyrimidine -CORRECTANSWER One carbon ring
Cytosine, Thymine, Uracil
Purine -CORRECTANSWER Two carbon rings
Adenine, Guanine
How are nucleotides joined together? -CORRECTANSWER Condensation to form
phosphodiester bond
What is the function of mRNA? -CORRECTANSWER Carries genetic info out of
nucleus
Transcript translated to protein
What is the function of tRNA? -CORRECTANSWER Carries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? -CORRECTANSWER part of ribosome structure
most abundant RNA
,coordinated coupling of tRNA to mRNA codons
Feedback inhibition -CORRECTANSWER Product of pathway is noncompetitive
inhibitor
Binds to allosteric site to slow down rxn b/c too much product
Exonucleases -CORRECTANSWER Degrades nucleic acids by removing one terminal
nt at a time
Cleaves phosphodiester bond at end of chain
5' --> 3' and 3' --> 5'
Endonucleases (Prok) -CORRECTANSWER Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites -CORRECTANSWER nt sequence where replication is initiated
Topoisomerase I -CORRECTANSWER Induces ss breaks
Remove DNA supercoils during TXN and DNA replication; for strand breakage during
recombination; for chr condensation; and to disentangle intertwined DNA during mitosis
,topoisomerase II -CORRECTANSWER cuts both strands of one DNA double helix,
passes another unbroken DNA helix through it, and then reanneals the cut strands
Gyrase (topoisomerase II) -CORRECTANSWER Unwinds supercoiling caused by
unwinding at the rep fork by introducing DSBs
Helicase -CORRECTANSWER Breaks H-bonds of double helix at the replication fork
Primase -CORRECTANSWER DNApol α (DNA dep RNA pol)
adds short segments of complementary
RNA to ssDNA template (primers), serves as starting points for replication
single-strand DNA binding proteins (SSBPs) -CORRECTANSWER Binds ssDNA and
prevents it from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments -CORRECTANSWER Short fragments of DNA synthesized by
DNApol δ using the lagging strand (3'->5') as a template
Ligase -CORRECTANSWER Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? -CORRECTANSWER 1. Initiate
2. Elongate
, 3. Terminate
Telomeres -CORRECTANSWER Repeat sequence (TTAGGG) at the ends of chr,
protect chr from degradation
RNA polymerase -CORRECTANSWER DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes -CORRECTANSWER Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers -CORRECTANSWER Short regions of DNA that bind proteins (TXN factors)
that enhance TXN of a gene
Poly-A tail -CORRECTANSWER Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap -CORRECTANSWER 5'-5' pyrophosphate bridge to a methylated G added to 5'
end of a mRNA
Protects against degradation and as a recognition signal for TLN apparatus
aminoacyl tRNA -CORRECTANSWER tRNAs that carry amino acids
Exam (2025) Exam Questions & Answers
| Latest Already Graded A+ UPDATE
2025|2026
Pyrimidine -CORRECTANSWER One carbon ring
Cytosine, Thymine, Uracil
Purine -CORRECTANSWER Two carbon rings
Adenine, Guanine
How are nucleotides joined together? -CORRECTANSWER Condensation to form
phosphodiester bond
What is the function of mRNA? -CORRECTANSWER Carries genetic info out of
nucleus
Transcript translated to protein
What is the function of tRNA? -CORRECTANSWER Carries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? -CORRECTANSWER part of ribosome structure
most abundant RNA
,coordinated coupling of tRNA to mRNA codons
Feedback inhibition -CORRECTANSWER Product of pathway is noncompetitive
inhibitor
Binds to allosteric site to slow down rxn b/c too much product
Exonucleases -CORRECTANSWER Degrades nucleic acids by removing one terminal
nt at a time
Cleaves phosphodiester bond at end of chain
5' --> 3' and 3' --> 5'
Endonucleases (Prok) -CORRECTANSWER Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites -CORRECTANSWER nt sequence where replication is initiated
Topoisomerase I -CORRECTANSWER Induces ss breaks
Remove DNA supercoils during TXN and DNA replication; for strand breakage during
recombination; for chr condensation; and to disentangle intertwined DNA during mitosis
,topoisomerase II -CORRECTANSWER cuts both strands of one DNA double helix,
passes another unbroken DNA helix through it, and then reanneals the cut strands
Gyrase (topoisomerase II) -CORRECTANSWER Unwinds supercoiling caused by
unwinding at the rep fork by introducing DSBs
Helicase -CORRECTANSWER Breaks H-bonds of double helix at the replication fork
Primase -CORRECTANSWER DNApol α (DNA dep RNA pol)
adds short segments of complementary
RNA to ssDNA template (primers), serves as starting points for replication
single-strand DNA binding proteins (SSBPs) -CORRECTANSWER Binds ssDNA and
prevents it from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments -CORRECTANSWER Short fragments of DNA synthesized by
DNApol δ using the lagging strand (3'->5') as a template
Ligase -CORRECTANSWER Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? -CORRECTANSWER 1. Initiate
2. Elongate
, 3. Terminate
Telomeres -CORRECTANSWER Repeat sequence (TTAGGG) at the ends of chr,
protect chr from degradation
RNA polymerase -CORRECTANSWER DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes -CORRECTANSWER Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers -CORRECTANSWER Short regions of DNA that bind proteins (TXN factors)
that enhance TXN of a gene
Poly-A tail -CORRECTANSWER Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap -CORRECTANSWER 5'-5' pyrophosphate bridge to a methylated G added to 5'
end of a mRNA
Protects against degradation and as a recognition signal for TLN apparatus
aminoacyl tRNA -CORRECTANSWER tRNAs that carry amino acids
