ASCP MOLECULAR BIOLOGY CERTIFICATION
EXAM QUESTIONS WITH CORRECT ANSWERS
2025-2026
Pyrimidine - CORRECT ANSWER -One carbon ring
Cytosine, Thymine, Uracil
Purine -sCORRECT ANSWER -Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - CORRECT ANSWER -Condensation to form phosphodiester bond
Whatsis the function of mRNA? - CORRECT ANSWER -Carries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - CORRECT ANSWER -Carries aa to ribosome
Anticodon pairs with codon on mRNAsstrand
Whatsis the function of rRNA? - CORRECT ANSWER -part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNAscodons
Feedbacksinhibition - CORRECT ANSWER -Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/cstoo much product
Exonucleases -sCORRECT ANSWER -Degrades nucleic acidssby removingsone terminal nt at a time
Cleaves phosphodiester bond at end of chain
5' --> 3' and 3' --> 5'
Endonucleases (Prok) - CORRECT ANSWER -Restriction enzymes
,Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site isspalindromic sequence
TypessI-V
ORI sites -sCORRECT ANSWERs-nt sequence where replication is initiated
Topoisomerase I - CORRECT ANSWERs-Induces ss breaks
Remove DNA supercoils during TXN and DNA replication; for strand breakage during recombination; for ch
r condensation; and to disentangle intertwined DNA during mitosis
topoisomerase II - CORRECT ANSWER -
cutssboth strands of one DNA double helix, passes another unbroken DNA helix through it, and then reann
eals thescut strands
Gyrase (topoisomerase II) -sCORRECT ANSWERs-
Unwinds supercoiling caused by unwindingsat the rep fork by introducingsDSBs
Helicase - CORRECT ANSWER -Breaks H-bonds of double helix at the replication fork
Primase - CORRECT ANSWER -DNApol α (DNA dep RNA pol)
adds shortssegments of complementary
RNA to ssDNA template (primers), serves assstartingspoints for replication
single-strand DNA binding proteins (SSBPs) - CORRECT ANSWER -Binds ssDNA and prevents it from re-
annealingsduring TXN, replication, repair, and recombination
Okazaki fragments - CORRECT ANSWER -
Short fragmentssof DNA synthesized by DNApol δ using the lagging strand (3'->5') as a template
Ligase -sCORRECT ANSWER -Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
,What are the steps in DNA replication? - CORRECT ANSWER -1. Initiate
2. Elongate
3. Terminate
Telomeres - CORRECT ANSWER -
Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation
RNAspolymerase - CORRECT ANSWER -DNAsdependent RNApol
Transcribes DNA template to RNAs(3'-->5'; anti-parallel)
Splicesomes - CORRECT ANSWER -Complex of snRNPs
Removessintrons from pre-mRNA and splices exons together
Enhancers -sCORRECT ANSWER -
Short regions of DNA that bind proteins (TXN factors) that enhance TXN of a gene
Poly-A tail - CORRECT ANSWER -Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' caps- CORRECT ANSWER -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 - CORRECT ANSWER -tRNAs that carry amino acids
Ribosomes - CORRECT ANSWER -Where TLN occurs
Prok: 30ssand 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
, What is the path of a tRNA in a ribosome? - CORRECT ANSWER -Acceptor > Peptidyl > Exit
How is translation initiated? - CORRECT ANSWER -
small rRNA (40S) subunit binds mRNA and scans for start codon (AUG)
Met-tRNA issbrought to the P site
Large rRNAs(60S) subunit binds
How is translation terminated? - CORRECT ANSWER -Occurs when stop codon enters Assite
Release factor recognizes stop codon, hydrolyzes ester bond with P site, releasing aa chain
Reverse transcriptase - CORRECT ANSWER -enzyme that transcribes RNA to cDNA (lacks introns)
RNAs--> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - CORRECT ANSWER -a single gene controls the expression of many phenotypicstraits
ie Sickle Cell Anemia
cDNA - CORRECT ANSWER -intron free complementary DNA
can be inserted into a plasmid
Vector -sCORRECT ANSWERs-helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) -sCORRECT ANSWER -
sections of DNA that begin with start codons and end with stop codons
DNA: 5' --> 3'
transcription: 3' --> 5' DNAs--> RNA (promoter)
translation: 5' --> 3' mRNA
EXAM QUESTIONS WITH CORRECT ANSWERS
2025-2026
Pyrimidine - CORRECT ANSWER -One carbon ring
Cytosine, Thymine, Uracil
Purine -sCORRECT ANSWER -Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - CORRECT ANSWER -Condensation to form phosphodiester bond
Whatsis the function of mRNA? - CORRECT ANSWER -Carries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - CORRECT ANSWER -Carries aa to ribosome
Anticodon pairs with codon on mRNAsstrand
Whatsis the function of rRNA? - CORRECT ANSWER -part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNAscodons
Feedbacksinhibition - CORRECT ANSWER -Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/cstoo much product
Exonucleases -sCORRECT ANSWER -Degrades nucleic acidssby removingsone terminal nt at a time
Cleaves phosphodiester bond at end of chain
5' --> 3' and 3' --> 5'
Endonucleases (Prok) - CORRECT ANSWER -Restriction enzymes
,Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site isspalindromic sequence
TypessI-V
ORI sites -sCORRECT ANSWERs-nt sequence where replication is initiated
Topoisomerase I - CORRECT ANSWERs-Induces ss breaks
Remove DNA supercoils during TXN and DNA replication; for strand breakage during recombination; for ch
r condensation; and to disentangle intertwined DNA during mitosis
topoisomerase II - CORRECT ANSWER -
cutssboth strands of one DNA double helix, passes another unbroken DNA helix through it, and then reann
eals thescut strands
Gyrase (topoisomerase II) -sCORRECT ANSWERs-
Unwinds supercoiling caused by unwindingsat the rep fork by introducingsDSBs
Helicase - CORRECT ANSWER -Breaks H-bonds of double helix at the replication fork
Primase - CORRECT ANSWER -DNApol α (DNA dep RNA pol)
adds shortssegments of complementary
RNA to ssDNA template (primers), serves assstartingspoints for replication
single-strand DNA binding proteins (SSBPs) - CORRECT ANSWER -Binds ssDNA and prevents it from re-
annealingsduring TXN, replication, repair, and recombination
Okazaki fragments - CORRECT ANSWER -
Short fragmentssof DNA synthesized by DNApol δ using the lagging strand (3'->5') as a template
Ligase -sCORRECT ANSWER -Closes gaps in DNA
Catalyzes phosphodiester bond between 3'OH and 5'P
,What are the steps in DNA replication? - CORRECT ANSWER -1. Initiate
2. Elongate
3. Terminate
Telomeres - CORRECT ANSWER -
Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation
RNAspolymerase - CORRECT ANSWER -DNAsdependent RNApol
Transcribes DNA template to RNAs(3'-->5'; anti-parallel)
Splicesomes - CORRECT ANSWER -Complex of snRNPs
Removessintrons from pre-mRNA and splices exons together
Enhancers -sCORRECT ANSWER -
Short regions of DNA that bind proteins (TXN factors) that enhance TXN of a gene
Poly-A tail - CORRECT ANSWER -Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' caps- CORRECT ANSWER -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 - CORRECT ANSWER -tRNAs that carry amino acids
Ribosomes - CORRECT ANSWER -Where TLN occurs
Prok: 30ssand 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
, What is the path of a tRNA in a ribosome? - CORRECT ANSWER -Acceptor > Peptidyl > Exit
How is translation initiated? - CORRECT ANSWER -
small rRNA (40S) subunit binds mRNA and scans for start codon (AUG)
Met-tRNA issbrought to the P site
Large rRNAs(60S) subunit binds
How is translation terminated? - CORRECT ANSWER -Occurs when stop codon enters Assite
Release factor recognizes stop codon, hydrolyzes ester bond with P site, releasing aa chain
Reverse transcriptase - CORRECT ANSWER -enzyme that transcribes RNA to cDNA (lacks introns)
RNAs--> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - CORRECT ANSWER -a single gene controls the expression of many phenotypicstraits
ie Sickle Cell Anemia
cDNA - CORRECT ANSWER -intron free complementary DNA
can be inserted into a plasmid
Vector -sCORRECT ANSWERs-helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) -sCORRECT ANSWER -
sections of DNA that begin with start codons and end with stop codons
DNA: 5' --> 3'
transcription: 3' --> 5' DNAs--> RNA (promoter)
translation: 5' --> 3' mRNA
