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30 Cards in this Set
- Front
- Back
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What are the four basic molecular genetic processes?
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1. Transcription
2. RNA processing 3. Translation 4. Replication |
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What is copying of DNA to RNA?
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Transcription
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What is RNA processing?
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It is the modification and transport of RNA to the cytoplasm (take out the introns, add cap and tail.)
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What is the synthesis of protein from mRNA?
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Translation
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What is the copying of DNA to DNA?
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Replication
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What links the ribose/base together from 5 to 3?
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Phosphodiester bonds
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What are the purines and explain what makes up a purine.
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The two purines are Adenine and Guanine. Purine means two rings (1 5-ring and 1 6-ring).
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What are the basics of a DNA helix? (width?, length of DNA per turn[nm and bp?, form?)
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DNA is antiparallel. It is 2 nm in width, 3.6 nm per turn, and 10.5 base pairs per turn. It is usually in the B form.
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How many H bonds does A have? What about C?
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Adenine has 2 Hydrogen bonds, while Cytosine has 3 Hydrogen bonds.
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What is the length of a B-from double-stranded DNA molecule 10500 bps long?
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3.6 x 1000=3600 nm or 3.6 microns
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Explain why DNA is more stable than RNA.
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The 2' hydroxyl on ribose permits hydrolysis of the phosphodiester bond. The H on the deoxyribose, however, does not so it is harder to break.
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The melting temperature is proportional to the ________ content.
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Guanine and Cystine content.
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How do you reduce torsional stress of circular DNA after replication?
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You would nick the supercoil (one strand) with the topoisomerase enzymes.
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What enzyme transcribes the DNA template strand? What part of the nucleoside triphosphate becomes part of the phosphodiester bond?
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RNA polymerase. The alpha phosphate.
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What is the area that allows the RNA polymerase to know where to begin?
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The promoter region.
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Describe in detail the stages of transcription.
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Initiation: 1. Polymerase binds to promoter sequence in duplex DNA. "Closed complex".2. Polymerase melts duplex DNA near start site to form a transcription bubble. 3. Polymerase catalyzes phoshodiester linkage of two intial rNTPs. Elongation: 4. Polymerase advances 3 to 5 down template melting duplex and adding rNTPs. Termination: 5. At stop site, polymerase releases RNA and dissociates from DNA.
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What are the names of the subunits in bacterial RNA polymerase?
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Beta subunit, Beta' subunit, Alpha subunit, and Omega subunit
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What is the size of the transcription bubble?
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12-14 bps!
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What are the differences between gene organization in prokaryotes and eukaryotes?
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In prokaryotes, genes are organized together in an operon that will create a single mRNA with separate start sites. The Eukaryote has genes separated in the genome that go to different mRNAs. Also, there is no processing in prokaryotes.
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What are the parts of processing in eukaryotes?
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The 5' 7 mehtylguanylate cap residue (also the methyl residues added to the ribose of the first and second base). The poly(A) tail. The splicing on introns and ligating of exons
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How many aminoacyl-tRNA synthetases are there? What does it mean to have a wobble position?
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20. The wobble position can use non-standard base pairing with the third base of the codon.
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What are the start and stop codons?
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start: AUG; stop: UGA, UAG, UAA
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What is S for the large and small ribosome for both prokaryotes and eukaryotes?
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Prokaryotes: 50S + 30S gives 70S.
Eukayotes: 60 S +40S gives 80 S |
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Go through the steps of pre-initiation and initiation in eukaryotes for translation.
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1. Ternary complex formed (Elf, Gtp, meth.tRNA) with 40S to form preinitiation complex. 2. The preintiation complex binds with the cap structure of the mRNA to form the intiation complex. 3. 40S scans until reaching AUG. 4. 60S joins the 40S with initiator tRNA in peptidyl (P) site.
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Go through the steps of peptide chain elongation in eukaryotes.
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1. Charged tRNA for next codon enters ribosome at the A stie. 2. GTP hydrolysis promotes conformational change that postions the two tRNAs for peptide bond formation. 3. Peptide bond formation is catalyzed by large ribosomal RNA. 4. GTP hydrolysis promotes ribosome translocation to the next codon on the the mRNA (tRNAs move to E site and P sites, leaving A site available for next tRNA). 5. Translation terminates when the riboome reaches stop codon. eRF1 enters at or near A stie together with eRF3-GTP. GTP hydrolysis then promotes release of polypeptide and tRNAs as well as dissocaition of 80S ribosome.
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What helps to synthesize DNA in replication? Can it do this de novo? What about for RNA transcription?
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DNA polymerase. No, it needs a primer. For transcription, RNA polymerase does not need a precurser.
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What is the difference between the leading and lagging strand in DNA replication?
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The leading strand synthesizes DNA normally 5' to 3'. The lagging strand, however, has to have the primase sythesize RNA primers, then DNA polyerase elongates the primers, then the primers are removed and gaps filled, finally Okazaki fragments are joined by DNA ligase.
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What DNA polymerase is responsible for replication in eukaryotes? prokaryotes?
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DNA polymerase delta.
DNA polymerase III. |
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What is the number of damage events per day to a single cell? What are the six ways of DNA repair?
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10,000 to 1,000,000. DNA polymerase proofreading, base excision repair, mismatch excision repair, nucleotide excision repair, nonhomologous end-joingin, homologous recombination.
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What is hereditary nonpolyposis colorectal cancer and hereditary xeroderma pigmentosum caused by?
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The first is caused by the loss of function in one copy of either MLH1 or MSH2 genes involved in mismatch excision repair. Xerodermas is often due to mutations in endonucleases required for nucleotide excision repair.
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