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50 Cards in this Set
- Front
- Back
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Who identified the "transforming principle"?
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Griffith
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Who convincingly showed that DNA is the genetic material using bacteriophage T2?
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Hershey and Chase
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Who noted the pattern in occurrence of four bases?
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Erwin Chargaff
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What are the two pyrimidines?
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T and C
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What are the two purines?
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G and A
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What is the sugar residue used in RNA?
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Ribose
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What is the sugar residue used in DNA?
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Deoxyribose
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What type of linkage links the nucleic acid portion to the sugar?
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B-N-glycosidic linkage
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What are nucleosides converted into?
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Phosphate ester
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What does the phosphate group of a nucleotide act as?
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Strong acid
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Why are DNA and RNA called nucleic acids?
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Because the phosphate group of a nucleotide acts as a strong acid.
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What sugar can form different "puckered" conformations
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Ribose
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What is the conformation if the carbon that is "pushed out" is in the same direction as C-5?
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Endo
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What groups on bases can be protonated?
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Amine groups
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What is tautomerization?
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Redistribution of positions of hydrogens and double bonds.
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What is the conformation (syn or anti) when the base portion is facing away from the sugar?
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Anti
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What is a common way that bases are modified?
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Methylation
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Which nucleotide is frequently found in modified form?
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Cytosine
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At what part of the spectrum do nucleotides absorb light?
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UV region
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Why is it possible to use spectophotometry to quantitate DNA and RNA?
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Because nucleotides absorb light strongly in the near-UV region.
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Linkage in RNA and DNA occurs through what?
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Phosphodiester link
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How does phosphodiester linkage occur?
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Hydrolysis of a nucleoside triphosphate
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T/F: A-T and G-C base pairs are identical in size and shape?
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True
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Which base pair has three hydrogen bonds?
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G-C
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DNA is arranged in what type of structure?
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Double helix
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What forms the backbone of the double helix?
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Sugar-phosphate
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Does the sugar-phosphate backbone on the outside of the helix carry a positive or negative charge?
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Negative
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What neutralizes the negative charge of the backbone when DNA is in solution?
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Metal ions
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What neutralizes the negative charge on the backbone on DNA In Vivo?
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Positively charged proteins
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What are the two grooves in the helix called?
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Major and minor groove
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What fact allows for the complementary sequence to be found?
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DNA chains are antiparallel
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Which form of DNA is left handed?
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Z-DNA
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Which form of DNA is the principle form of RNA?
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A-form
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Which form of DNA has the largest diameter
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A-form
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Which form of DNA is the predominant form in solution?
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B-form
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What is the process of strand separation called?
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Denaturation (or melting)
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What is the hypochromic effect?
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The absorption of 260nm light by DNA is about 40% lower than the sum of the individual bases. This is due to base stacking in DNA.
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Max Airspeed: Aircraft GW > _____ lbs with an external load
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22,000
120 kts |
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Explain hyperchromic shift.
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When DNA duplex is denatured, the stacking of bases is disrupted and there is an increase in absorbance at 260nm.
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For every percent increase in GC content, Tm increases by how much?
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0.4C
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Tm increases by 16.6C for every 10-fold increase in what?
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monovalent cation concentration
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What can reduce Tm considerably?
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Reagents that destabilize H-bonds (such as formamide)
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The ability of two separated complementary strands to reform into double helix is called what?
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Renaturation
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The percentage of what determines the buoyant density of DNA in concentrated CsCl solutions?
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G+C
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Which has a higher buoyant density: GC-rich DNA or AT-rich DNA?
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GC rich
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tRNA works in what process?
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Protein synthesis
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What is it called when DNA twists around its own axis (like a rubber band)?
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Supercoiling
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What is the formula for supercoiling?
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L=T+W where L=linking number; T=twist; W=writhe
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What relaxes negatively supercoiled DNA by increasing its linking number?
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Type I topoisomerase
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What technique causes DNA fragments to move through pores at a rate inversely proportional to their chain length?
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Agarose Gel Electrophoresis
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