All about DNA/RNA – Flashcards
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Purpose of Nucleotides?
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Metabolic intermediates, chemical messengers, cofactors, building blocks of nucleic acids
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Role of Nucleic Acids?
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Genetic information and Structural role
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What does a nucleotide consist of?
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Phosphate+sugar+base
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What does a nucleotide consist of?
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Phosphate+sugar+base
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What does a nucleoside consist of?
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Sugar + base
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What is larger? Pyrimidine or Purine?
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Purine
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What is stronger? A-T/U or C-G?
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C-G because it has 3 bonds. Therefore, the more CG bonds, the higher the melting temp
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Examples of Purines?
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A,G
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Pyrimidines?
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C,T,U
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Difference between DNA and RNA sugars?
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DNA has H, RNA has OH
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Are A,T,C,G,U the only bases?
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Nope, minor ones exist too
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Which carbon is the phosphate of the standard AMP attached to?
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Carbon 5 (but it can attach in other places too)
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Typical pattern of DNA strand?
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5 end with phosphate, then sugar, phosphate.....finally 3 end
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Backbone of DNA is hydrophobic or hydrophilic?
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hydrophilic
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Base pairs are hydrophobic or hydrophilic?
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Hydrophobic
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Which is more susceptible to alkaline hydrolysis? DNA or RNA?
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RNA because of the OH that can get deprotanated easily
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How many nucleotides long are oligonucelotides?
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Less than 50
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Light absorbance of nucleic acids?
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260 nm
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Shape of the bases?
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flat
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Two important features that help shape nucleic acids?
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Base-stacking and base-pairing
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PH of bases?
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near neutral
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What is primary NA structure?
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sequence
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Secondary Nucleic Acid Structure?
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local interactions and patterns such as watson crick
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Tertiary Nucleic Acid Structure?
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3 Dimensional longer range involving other moleucles
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What are the 3 forms of DNA?
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A,B,Z
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Which DNA form doesnt exist in nature
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A form
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What DNA form is the most common?
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B form
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What DNA form is the thinnest?
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Z form
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How many bases per turn in the Watson Crick Model?
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10.5 bases per turn
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Pattern of DNA groves?
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1 major grove, then 1 minor grove, repeat
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Which DNA forms are right handed?
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A and B
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Which DNA forms are left handed?
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zform
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What is perpendicular to the DNA backbone axis?
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base pairs
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True or False? Z form is more elongated than B form.
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TRUE
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Which DNA form is favored in the absence of water?
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A form of DNA, only occurs in the lab though
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Which DNA has the largest diameter (widest)?
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A form of DNA
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If one DNA stand is 5 A T C G 3, what is the other strand?
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3 T A G C 5
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T or F? Palindromes can occur on the same and opposite strands?
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TRUE
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What forms the hairpin loop? GGATACTCGATCC
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ACTC
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Palindromes need at least ____ base pairs.
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4 base pairs
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Double stranded palindrome can form what?
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cruciform structure
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T or F? 3 and 4 stranded DNA structures exist
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yes
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Are prokaryote RNA mono or polycistronic?
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It can be both. The mRNA can contain 1 or more genes.
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Are eukaryote mRNA mono or polycistronic?
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strictly monocistronic
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Helical RNA is typically in what form?
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A form
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T or F? Helical RNA in the Z form exists
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True but only in labs
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T or F? Helical RNA in B form exists
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False. Never has been observed
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Riboenzymes are an example or primary, secondary, or teritiary RNA structure?
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tertiary
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What happens to UV absorption as DNA strands break?
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Absorbance changes
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What is Tm?
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Temperature where half the DNA is denatured. It is different for different DNA strands
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What happens to Tm as G+C base pairs increase?
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Tm goes up because it is harder to break.
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Hybrid duplexes form when the DNA strands are ________.
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Complementary
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In hybridization, rank the strengths of nucleic acid bonds.
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RNA:RNA;RNA:DNA;DNA:DNA
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Applications of NA Hybridization?
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Research of relatedness of species, forensic medicine, diagnostic tests, drugs
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Give 3 examples of 3 important spontaeous but rare reactions changing Nucleic Acids:
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Deamination, Depurination, Dimer Formation
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Give 3 examples of reactive chemicals that can affect nucleic acids:
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1)Deaminating agents such as Nitrites,nitrates, nitrosamines, bisulfuite. 2) alkylating agents that disrupt base pairing such as dimethylsulfate 3) oxidizing agents
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What is the purpose of DNA methylation (alkylation)?
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It can provide natural protection. Happens in E-coli naturally
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What does methylation of cytosine do to DNA structure?
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Leads some DNA segments to assume the Z form
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What does the human genome project do?
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Determination of DNA sequence.
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What is the maximum number of nucleotides synthesized in the lab?
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Usually 70-80 though it can be more (rarely)
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What are the 3 functions of nucelotides?
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energy carriers, componenets of enzyme cofactors, regulatory molecules
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Examples of energy carriers:
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amp, adp, atp, adensosine
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Examples of enzyme cofactors:
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coenzyme A, NAD,FAD
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Examples of Regulatory molecules
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cAMP,cGMP,ppGpp
