ASCP Molecular Biology Certification Exam fully
solved & updated (latest version verified for
accuracy)|| GRADED A+||LATEST UPDATE 2025/26
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
solved & updated (latest version verified for
accuracy)|| GRADED A+||LATEST UPDATE 2025/26
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
