ASCP Molecular Biology Exam 2026
QUESTIONS AND 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
What does mRNA do? - Correct Answer -carries code out of cell.
code for protein structure.
DNA to ribosomes
end of transcription start of translation
What does tRNA do? - Correct Answer -decodes mRNA. Matches amino acids to
mRNA code. Protein synthesis
What does rRNA do? - Correct Answer -part of ribosome structure
most abundant RNA
©COPYRIGHT 2025 ALL RIGHTS RESERVED 1
,coordinated coupling of tRNA to mRNA codons
Feedback Inhibition - Correct Answer -end 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
nucleotide at a time
cleaves phosphodiester bond at end of chain
5' ---> 3' and 3' ---> 5'
Endonucleases - Correct Answer -cleaves phoshpodiester bonds w/in chain
recognition site is palindromic sequence
cleaves unevenly, leaves sticky ends
(restriction enzymes)
DNA polymerase III - Correct Answer -copies DNA by reading existing strand,
builds new comp. strand
always adds to 3' end
can't start new strand on its own (ORI sites)
ORI sites - Correct Answer -origin of replication on chromosome
©COPYRIGHT 2025 ALL RIGHTS RESERVED 2
,triggers DNA replication
gyrase - Correct Answer -unwinds DNA in front of fork
DNA polymerase I - Correct Answer -removes RNA nucleotides form RNA
primers and replaces with DNA
(makes sure primers that start replication are removed)
helicase - Correct Answer -breaks H-bonds of double helix
topoisomerase - Correct Answer -breaks/ reseals DNA backbone to release tension
caused by twisting
(DNA gyrase)
primase - Correct Answer -(RNA pol)
primers, small RNA, serves as starting points for copying DNA
helper enzyme for DNA pol III
single-strand DNA-binding proteins (SSBPs) - Correct Answer -hold DNA open
during replication
Okazaki fragments - Correct Answer -lagging strand
3' ---> 5'
away from fork
©COPYRIGHT 2025 ALL RIGHTS RESERVED 3
, DNA pol III adds, DNA ligase closes gaps
Ligase - Correct Answer -closes gaps in DNA
forms covalent bonds b/w nucleotides, 3' end of new DNA to 5' end of growing
chain
What are the steps in DNA replication? - Correct Answer -1. Initiate
2. Elongate
3. Terminate
Telomers - Correct Answer -cap ends of chromosome during replication to
preserve DNA
-10 box - Correct Answer -TATA box (TATAAT)
located 10 bases away from transcription start site
promoter
RNA pol binding site
-35 box - Correct Answer -TTGACA
located 35 bases away from transcription start site
promoter
©COPYRIGHT 2025 ALL RIGHTS RESERVED 4
QUESTIONS AND 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
What does mRNA do? - Correct Answer -carries code out of cell.
code for protein structure.
DNA to ribosomes
end of transcription start of translation
What does tRNA do? - Correct Answer -decodes mRNA. Matches amino acids to
mRNA code. Protein synthesis
What does rRNA do? - Correct Answer -part of ribosome structure
most abundant RNA
©COPYRIGHT 2025 ALL RIGHTS RESERVED 1
,coordinated coupling of tRNA to mRNA codons
Feedback Inhibition - Correct Answer -end 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
nucleotide at a time
cleaves phosphodiester bond at end of chain
5' ---> 3' and 3' ---> 5'
Endonucleases - Correct Answer -cleaves phoshpodiester bonds w/in chain
recognition site is palindromic sequence
cleaves unevenly, leaves sticky ends
(restriction enzymes)
DNA polymerase III - Correct Answer -copies DNA by reading existing strand,
builds new comp. strand
always adds to 3' end
can't start new strand on its own (ORI sites)
ORI sites - Correct Answer -origin of replication on chromosome
©COPYRIGHT 2025 ALL RIGHTS RESERVED 2
,triggers DNA replication
gyrase - Correct Answer -unwinds DNA in front of fork
DNA polymerase I - Correct Answer -removes RNA nucleotides form RNA
primers and replaces with DNA
(makes sure primers that start replication are removed)
helicase - Correct Answer -breaks H-bonds of double helix
topoisomerase - Correct Answer -breaks/ reseals DNA backbone to release tension
caused by twisting
(DNA gyrase)
primase - Correct Answer -(RNA pol)
primers, small RNA, serves as starting points for copying DNA
helper enzyme for DNA pol III
single-strand DNA-binding proteins (SSBPs) - Correct Answer -hold DNA open
during replication
Okazaki fragments - Correct Answer -lagging strand
3' ---> 5'
away from fork
©COPYRIGHT 2025 ALL RIGHTS RESERVED 3
, DNA pol III adds, DNA ligase closes gaps
Ligase - Correct Answer -closes gaps in DNA
forms covalent bonds b/w nucleotides, 3' end of new DNA to 5' end of growing
chain
What are the steps in DNA replication? - Correct Answer -1. Initiate
2. Elongate
3. Terminate
Telomers - Correct Answer -cap ends of chromosome during replication to
preserve DNA
-10 box - Correct Answer -TATA box (TATAAT)
located 10 bases away from transcription start site
promoter
RNA pol binding site
-35 box - Correct Answer -TTGACA
located 35 bases away from transcription start site
promoter
©COPYRIGHT 2025 ALL RIGHTS RESERVED 4
