ASCP MOLECULAR BIOLOGY CERTIFICATION EXAM
QUESTIONS WITH CORRECT ANSWERS 2025
How are nucleotides joined together? - CORRECT ANSWER -
Condensation to form phosphodiester bond
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
Telomeres - CORRECT ANSWER -
Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation
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
Ribosomes - CORRECT ANSWER -Where TLN occurs
Prok: 30s and 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
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)
Pleiotrophy - CORRECT ANSWER -a single gene controls the expression of many phenotypic traits
ie Sickle Cell Anemia
cDNA - CORRECT ANSWER -intron free complementary DNA
can be inserted into a plasmid
Vector - CORRECT ANSWER -helps carry DNA into cell
,ie plasmids, virus
Open Reading Frame (ORF) - CORRECT 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 - CORRECT ANSWER -Measures amount of light absorbed
Quantitative measurement of [DNA/RNA]
Organic isolation method - CORRECT ANSWER -1. Lyse
2. Add phenol/ chloroform > vortex/spin
3. Transfer aqueous layer (top) to new tube
4. Add chloroform:IAA (removes phenol) > vortex/spin
5. Transfer aqueous layer to new tube
6. Add NaOAc and EtOH > vortex/spin
7. Decant
8. Resuspend
How do you inactivate RNases? - CORRECT ANSWER -200C for 2 hrs
30 min in 1M NaOH or quanidinum isothiocyanate
Hybridization - CORRECT ANSWER -
2 ssDNA molecules of comp base sequence can form a ds hybrid (duplex)
What does the incubation step in hybridization do? - CORRECT ANSWER -
Allows formation of ds molecules
Blocking DNA (Hybridization) - CORRECT ANSWER -minimizes probe binding to nonspecific sequence
, ie salmon sperm DNA, Human LINE-1
Blocking Proteins (Hybridization) - CORRECT ANSWER -
minimize nonspecific binding of probe to membrane
ie casein (milk), Denhardt's sol
How can you increase strigency in a hybridization? - CORRECT ANSWER -decrease [salt]
increase [formamide]
increase temp
Line Probe Assay (LiPA) - CORRECT ANSWER -reverse hybridization assay using sequence-
specific oligonucleotide probes (reverse SSOP)
multi-parameter testing --> single strip
Line Probe Assay steps - CORRECT ANSWER -1. Isolate nucleic acid (RNA)
2. Amplify
3. Hybridization
4. Strigent wash
5. Incubate with conjugate
6. Incubate with substrate
7. Detect
What method would you use if you knew the gene sequence and the mutation? -
CORRECT ANSWER -Reverse Dot Blot
Microarrays - CORRECT ANSWER -Used for unknown gene and mutation
cDNA libraries
can be used for gene expression, tumors, genetic mapping, mutations and polymorphism
large scale, high throughput analysis
QUESTIONS WITH CORRECT ANSWERS 2025
How are nucleotides joined together? - CORRECT ANSWER -
Condensation to form phosphodiester bond
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
Telomeres - CORRECT ANSWER -
Repeat sequence (TTAGGG) at the ends of chr, protect chr from degradation
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
Ribosomes - CORRECT ANSWER -Where TLN occurs
Prok: 30s and 50s
Euk: 40s and 60s
Catalyzes peptide bond between a.a.'s
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)
Pleiotrophy - CORRECT ANSWER -a single gene controls the expression of many phenotypic traits
ie Sickle Cell Anemia
cDNA - CORRECT ANSWER -intron free complementary DNA
can be inserted into a plasmid
Vector - CORRECT ANSWER -helps carry DNA into cell
,ie plasmids, virus
Open Reading Frame (ORF) - CORRECT 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 - CORRECT ANSWER -Measures amount of light absorbed
Quantitative measurement of [DNA/RNA]
Organic isolation method - CORRECT ANSWER -1. Lyse
2. Add phenol/ chloroform > vortex/spin
3. Transfer aqueous layer (top) to new tube
4. Add chloroform:IAA (removes phenol) > vortex/spin
5. Transfer aqueous layer to new tube
6. Add NaOAc and EtOH > vortex/spin
7. Decant
8. Resuspend
How do you inactivate RNases? - CORRECT ANSWER -200C for 2 hrs
30 min in 1M NaOH or quanidinum isothiocyanate
Hybridization - CORRECT ANSWER -
2 ssDNA molecules of comp base sequence can form a ds hybrid (duplex)
What does the incubation step in hybridization do? - CORRECT ANSWER -
Allows formation of ds molecules
Blocking DNA (Hybridization) - CORRECT ANSWER -minimizes probe binding to nonspecific sequence
, ie salmon sperm DNA, Human LINE-1
Blocking Proteins (Hybridization) - CORRECT ANSWER -
minimize nonspecific binding of probe to membrane
ie casein (milk), Denhardt's sol
How can you increase strigency in a hybridization? - CORRECT ANSWER -decrease [salt]
increase [formamide]
increase temp
Line Probe Assay (LiPA) - CORRECT ANSWER -reverse hybridization assay using sequence-
specific oligonucleotide probes (reverse SSOP)
multi-parameter testing --> single strip
Line Probe Assay steps - CORRECT ANSWER -1. Isolate nucleic acid (RNA)
2. Amplify
3. Hybridization
4. Strigent wash
5. Incubate with conjugate
6. Incubate with substrate
7. Detect
What method would you use if you knew the gene sequence and the mutation? -
CORRECT ANSWER -Reverse Dot Blot
Microarrays - CORRECT ANSWER -Used for unknown gene and mutation
cDNA libraries
can be used for gene expression, tumors, genetic mapping, mutations and polymorphism
large scale, high throughput analysis
