ASCP Molecular Biology Certification
Exam 2025 With 100% Correct
Answers
Pyrimidine - CORRECT ANSWER✔✔One carbon ring
Cytosine, Thymine, Uracil
Purine - CORRECT ANSWER✔✔Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - CORRECT ANSWER✔✔Condensation to form
phosphodiester bond
What is 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 mRNA strand
What is the function of rRNA? - CORRECT ANSWER✔✔part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - CORRECT ANSWER✔✔Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
,Exonucleases - CORRECT ANSWER✔✔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) - CORRECT ANSWER✔✔Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - CORRECT ANSWER✔✔nt sequence where replication is initiated
Topoisomerase I - CORRECT ANSWER✔✔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 - CORRECT ANSWER✔✔cuts both strands of one DNA double helix, passes
another unbroken DNA helix through it, and then reanneals the cut strands
Gyrase (topoisomerase II) - CORRECT ANSWER✔✔Unwinds supercoiling caused by unwinding at
the rep fork by introducing DSBs
Helicase - CORRECT ANSWER✔✔Breaks H-bonds of double helix at the replication fork
Primase - CORRECT ANSWER✔✔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) - CORRECT ANSWER✔✔Binds ssDNA and prevents it
from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments - CORRECT ANSWER✔✔Short fragments of DNA synthesized by DNApol δ
using the lagging strand (3'->5') as a template
Ligase - CORRECT 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
RNA polymerase - CORRECT ANSWER✔✔DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - CORRECT ANSWER✔✔Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - CORRECT 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' cap - 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: 30s and 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 is brought to the P site
Large rRNA (60S) subunit binds
How is translation terminated? - CORRECT ANSWER✔✔Occurs when stop codon enters A site
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)
RNA --> RNA:DNA --> cDNA (dsDNA)
Exam 2025 With 100% Correct
Answers
Pyrimidine - CORRECT ANSWER✔✔One carbon ring
Cytosine, Thymine, Uracil
Purine - CORRECT ANSWER✔✔Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - CORRECT ANSWER✔✔Condensation to form
phosphodiester bond
What is 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 mRNA strand
What is the function of rRNA? - CORRECT ANSWER✔✔part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - CORRECT ANSWER✔✔Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
,Exonucleases - CORRECT ANSWER✔✔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) - CORRECT ANSWER✔✔Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - CORRECT ANSWER✔✔nt sequence where replication is initiated
Topoisomerase I - CORRECT ANSWER✔✔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 - CORRECT ANSWER✔✔cuts both strands of one DNA double helix, passes
another unbroken DNA helix through it, and then reanneals the cut strands
Gyrase (topoisomerase II) - CORRECT ANSWER✔✔Unwinds supercoiling caused by unwinding at
the rep fork by introducing DSBs
Helicase - CORRECT ANSWER✔✔Breaks H-bonds of double helix at the replication fork
Primase - CORRECT ANSWER✔✔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) - CORRECT ANSWER✔✔Binds ssDNA and prevents it
from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments - CORRECT ANSWER✔✔Short fragments of DNA synthesized by DNApol δ
using the lagging strand (3'->5') as a template
Ligase - CORRECT 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
RNA polymerase - CORRECT ANSWER✔✔DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - CORRECT ANSWER✔✔Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - CORRECT 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' cap - 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: 30s and 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 is brought to the P site
Large rRNA (60S) subunit binds
How is translation terminated? - CORRECT ANSWER✔✔Occurs when stop codon enters A site
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)
RNA --> RNA:DNA --> cDNA (dsDNA)
