ASCP Molecular Biology Certification Exam graded A+ 2022Pyrimidine
One carbon ring
Cytosine, Thymine, Uracil
Purine
Two carbon rings
Adenine, Guanine
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01:08
How are nucleotides joined together?
Condensation to form phosphodiester bond
What is the function of m...
ASCP Molecular Biology Certification Exam graded A+ 2022
Pyrimidine - correct answersOne carbon ring
Cytosine, Thymine, Uracil
Purine - correct answersTwo carbon rings
Adenine, Guanine
How are nucleotides joined together? - correct answersCondensation to form phosphodiester bond
What is the function of mRNA? - correct answersCarries genetic info out of nucleus
Transcript translated to protein
What is the function of tRNA? - correct answersCarries aa to ribosome
Anticodon pairs with codon on mRNA strand
What is the function of rRNA? - correct answerspart of ribosome structure
most abundant RNA
coordinated coupling of tRNA to mRNA codons
Feedback inhibition - correct answersProduct of pathway is noncompetitive inhibitor
Binds to allosteric site to slow down rxn b/c too much product
Exonucleases - correct answersDegrades 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 answersRestriction enzymes
Cleaves phoshpodiester bonds w/i poly-nt chain
Recognition site is palindromic sequence
Types I-V
ORI sites - correct answersnt sequence where replication is initiated
Topoisomerase I - correct answersInduces 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 answerscuts both strands of one DNA double helix, passes another unbroken DNA helix through it, and then reanneals the cut strands Gyrase (topoisomerase II) - correct answersUnwinds supercoiling caused by unwinding at the rep fork by introducing DSBs
Helicase - correct answersBreaks H-bonds of double helix at the replication fork
Primase - correct answersDNApol 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 answersBinds ssDNA and prevents it from re-annealing during TXN, replication, repair, and recombination
Okazaki fragments - correct answersShort fragments of DNA synthesized by DNApol δ using the lagging strand (3'->5') as a template
Ligase - correct answersCloses gaps in DNA Catalyzes phosphodiester bond between 3'OH and 5'P
What are the steps in DNA replication? - correct answers1. Initiate
2. Elongate
3. Terminate
Telomeres - correct answersRepeat sequence (TTAGGG) at the ends of chr, protect chr
from degradation
RNA polymerase - correct answersDNA dependent RNApol
Transcribes DNA template to RNA (3'-->5'; anti-parallel)
Splicesomes - correct answersComplex of snRNPs
Removes introns from pre-mRNA and splices exons together
Enhancers - correct answersShort regions of DNA that bind proteins (TXN factors) that enhance TXN of a gene
Poly-A tail - correct answersPrevents mRNA from being degraded in cytoplasm
100-250 A's at 3' end
5' cap - correct answers5'-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 answerstRNAs that carry amino acids
Ribosomes - correct answersWhere 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 answersAcceptor > Peptidyl > Exit
How is translation initiated? - correct answerssmall 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 answersOccurs when stop codon enters A site
Release factor recognizes stop codon, hydrolyzes ester bond with P site, releasing aa chain
Reverse transcriptase - correct answersenzyme that transcribes RNA to cDNA (lacks introns)
RNA --> RNA:DNA --> cDNA (dsDNA)
Pleiotrophy - correct answersa single gene controls the expression of many phenotypic traits
ie Sickle Cell Anemia
cDNA - correct answersintron free complementary DNA can be inserted into a plasmid
Vector - correct answershelps carry DNA into cell ie plasmids, virus
Open Reading Frame (ORF) - correct answerssections 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 answersMeasures amount of light absorbed
Quantitative measurement of [DNA/RNA]
At what wavelength does DNA and RNA absorb? - correct answers260 nm
At what wavelength does protein absorb? - correct answers280 nm
Organic isolation method - correct answers1. 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
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