ASCP Molecular Biology
Certification Exam
Reviewed Questions And
Answers GRADED A+ 2025-
2026
Pyrimidine - ANS-One carbon ring
Cytosine, Thymine, Uracil
Purine - ANS-Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - ANS-Condensation to form
phosphodiester bond
What is the function of mRNA? - ANS-Carries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - ANS-Carries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? - ANS-part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - ANS-Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
,Exonucleases - ANS-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) - ANS-Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - ANS-nt sequence where replication is initiated
Topoisomerase I - ANS-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 - ANS-cuts both strands of one DNA double helix, passes
another unbroken DNA helix through it, and then reanneals the cut strands
Gyrase (topoisomerase II) - ANS-Unwinds supercoiling caused by unwinding at
the rep fork by introducing DSBs
Helicase - ANS-Breaks H-bonds of double helix at the replication fork
Primase - ANS-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) - ANS-Binds ssDNA and prevents it
from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments - ANS-Short fragments of DNA synthesized by DNApol δ using
the lagging strand (3'->5') as a template
,Ligase - ANS-Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? - ANS-1. Initiate
2. Elongate
3. Terminate
Telomeres - ANS-Repeat sequence (TTAGGG) at the ends of chr, protect chr from
degradation
RNA polymerase - ANS-DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - ANS-Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - ANS-Short regions of DNA that bind proteins (TXN factors) that
enhance TXN of a gene
Poly-A tail - ANS-Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap - ANS-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 - ANS-tRNAs that carry amino acids
Ribosomes - ANS-Where TLN occurs
Prok: 30s and 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
, What is the path of a tRNA in a ribosome? - ANS-Acceptor > Peptidyl > Exit
How is translation initiated? - ANS-small rRNA (40S) subunit binds mRNA and
scans for start codon (AUG)
Met-tRNA is brought to the P site
Large rRNA (60S) subunit binds
How is translation terminated? - ANS-Occurs when stop codon enters A site
Release factor recognizes stop codon, hydrolyzes ester bond with P site,
releasing aa chain
Reverse transcriptase - ANS-enzyme that transcribes RNA to cDNA (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - ANS-a single gene controls the expression of many phenotypic
traits
ie Sickle Cell Anemia
cDNA - ANS-intron free complementary DNA
can be inserted into a plasmid
Vector - ANS-helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) - ANS-sections of DNA that begin with start codons
and end with stop codons
DNA: 5' --> 3'
transcription: 3' --> 5' DNA --> RNA (promoter)
translation: 5' --> 3' mRNA
Spectrophotometer - ANS-Measures amount of light absorbed
Quantitative measurement of [DNA/RNA]
Certification Exam
Reviewed Questions And
Answers GRADED A+ 2025-
2026
Pyrimidine - ANS-One carbon ring
Cytosine, Thymine, Uracil
Purine - ANS-Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - ANS-Condensation to form
phosphodiester bond
What is the function of mRNA? - ANS-Carries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - ANS-Carries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? - ANS-part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - ANS-Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
,Exonucleases - ANS-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) - ANS-Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - ANS-nt sequence where replication is initiated
Topoisomerase I - ANS-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 - ANS-cuts both strands of one DNA double helix, passes
another unbroken DNA helix through it, and then reanneals the cut strands
Gyrase (topoisomerase II) - ANS-Unwinds supercoiling caused by unwinding at
the rep fork by introducing DSBs
Helicase - ANS-Breaks H-bonds of double helix at the replication fork
Primase - ANS-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) - ANS-Binds ssDNA and prevents it
from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments - ANS-Short fragments of DNA synthesized by DNApol δ using
the lagging strand (3'->5') as a template
,Ligase - ANS-Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? - ANS-1. Initiate
2. Elongate
3. Terminate
Telomeres - ANS-Repeat sequence (TTAGGG) at the ends of chr, protect chr from
degradation
RNA polymerase - ANS-DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - ANS-Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - ANS-Short regions of DNA that bind proteins (TXN factors) that
enhance TXN of a gene
Poly-A tail - ANS-Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap - ANS-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 - ANS-tRNAs that carry amino acids
Ribosomes - ANS-Where TLN occurs
Prok: 30s and 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
, What is the path of a tRNA in a ribosome? - ANS-Acceptor > Peptidyl > Exit
How is translation initiated? - ANS-small rRNA (40S) subunit binds mRNA and
scans for start codon (AUG)
Met-tRNA is brought to the P site
Large rRNA (60S) subunit binds
How is translation terminated? - ANS-Occurs when stop codon enters A site
Release factor recognizes stop codon, hydrolyzes ester bond with P site,
releasing aa chain
Reverse transcriptase - ANS-enzyme that transcribes RNA to cDNA (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - ANS-a single gene controls the expression of many phenotypic
traits
ie Sickle Cell Anemia
cDNA - ANS-intron free complementary DNA
can be inserted into a plasmid
Vector - ANS-helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) - ANS-sections of DNA that begin with start codons
and end with stop codons
DNA: 5' --> 3'
transcription: 3' --> 5' DNA --> RNA (promoter)
translation: 5' --> 3' mRNA
Spectrophotometer - ANS-Measures amount of light absorbed
Quantitative measurement of [DNA/RNA]
