ASCP MOLECULAR BIOLOGY
CERTIFICATION EXAM QUESTIONS &
ANSWERS WITH SOLUTIONS 2024
Pyrimidine - ANSWER One carbon ring
Cytosine, Thymine, Uracil
Purine - ANSWER Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - ANSWER Condensation to form phosphodiester bond
What is the function of mRNA? - ANSWER Carries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - ANSWER Carries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? - ANSWER part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - ANSWER Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
Exonucleases - 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) - ANSWER Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - ANSWER nt sequence where replication is initiated
Topoisomerase I - 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 - 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) - ANSWER Unwinds supercoiling caused by unwinding at the rep fork by
introducing DSBs
Helicase - ANSWER Breaks H-bonds of double helix at the replication fork
Primase - 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) - ANSWER Binds ssDNA and prevents it from re-annealing
during TXN, replication, repair, and recombination
Okazaki fragments - ANSWER Short fragments of DNA synthesized by DNApol δ using the lagging strand
(3'->5') as a template
Ligase - ANSWER Closes gaps in DNA
,Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? - ANSWER 1. Initiate
2. Elongate
3. Terminate
Telomeres - ANSWER Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation
RNA polymerase - ANSWER DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - ANSWER Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - ANSWER Short regions of DNA that bind proteins (TXN factors) that enhance TXN of a gene
Poly-A tail - ANSWER Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap - 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 - ANSWER tRNAs that carry amino acids
Ribosomes - 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? - ANSWER Acceptor > Peptidyl > Exit
How is translation initiated? - 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? - ANSWER Occurs when stop codon enters A site
Release factor recognizes stop codon, hydrolyzes ester bond with P site, releasing aa chain
Reverse transcriptase - ANSWER enzyme that transcribes RNA to cDNA (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - ANSWER a single gene controls the expression of many phenotypic traits
ie Sickle Cell Anemia
cDNA - ANSWER intron free complementary DNA
can be inserted into a plasmid
Vector - ANSWER helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) - ANSWER 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 - ANSWER Measures amount of light absorbed
CERTIFICATION EXAM QUESTIONS &
ANSWERS WITH SOLUTIONS 2024
Pyrimidine - ANSWER One carbon ring
Cytosine, Thymine, Uracil
Purine - ANSWER Two carbon rings
Adenine, Guanine
How are nucleotides joined together? - ANSWER Condensation to form phosphodiester bond
What is the function of mRNA? - ANSWER Carries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - ANSWER Carries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? - ANSWER part of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - ANSWER Product of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
Exonucleases - 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) - ANSWER Restriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - ANSWER nt sequence where replication is initiated
Topoisomerase I - 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 - 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) - ANSWER Unwinds supercoiling caused by unwinding at the rep fork by
introducing DSBs
Helicase - ANSWER Breaks H-bonds of double helix at the replication fork
Primase - 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) - ANSWER Binds ssDNA and prevents it from re-annealing
during TXN, replication, repair, and recombination
Okazaki fragments - ANSWER Short fragments of DNA synthesized by DNApol δ using the lagging strand
(3'->5') as a template
Ligase - ANSWER Closes gaps in DNA
,Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? - ANSWER 1. Initiate
2. Elongate
3. Terminate
Telomeres - ANSWER Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation
RNA polymerase - ANSWER DNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - ANSWER Complex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - ANSWER Short regions of DNA that bind proteins (TXN factors) that enhance TXN of a gene
Poly-A tail - ANSWER Prevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap - 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 - ANSWER tRNAs that carry amino acids
Ribosomes - 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? - ANSWER Acceptor > Peptidyl > Exit
How is translation initiated? - 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? - ANSWER Occurs when stop codon enters A site
Release factor recognizes stop codon, hydrolyzes ester bond with P site, releasing aa chain
Reverse transcriptase - ANSWER enzyme that transcribes RNA to cDNA (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - ANSWER a single gene controls the expression of many phenotypic traits
ie Sickle Cell Anemia
cDNA - ANSWER intron free complementary DNA
can be inserted into a plasmid
Vector - ANSWER helps carry DNA into cell
ie plasmids, virus
Open Reading Frame (ORF) - ANSWER 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 - ANSWER Measures amount of light absorbed
