Nucleic acids and DNA replication

  • Created by: AminA1000
  • Created on: 26-10-18 17:15
significance of DNA to organisms
DNA holds genetic info, RNA transfers genetic info from DNA to ribosomes
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What are ribosomes formed from
RNA and proteins
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similarities of DNA and RNA
Both polynucleotides , ach nucleotide is formed from a pentose, a nitrogen-containing organic base and a phosphate group:
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differences of DNA and RNA
DNA=AT,GC RNA=AU,GC DNA= double polynucleotide chains, RNA=single. DNA=double helix ,RNA=single. DNA=chemically very stable,RNA=chemically unstable. DNA=deoxyribose pentose sugar,RNA=ribose pentose sugar. DNA=long molecule,RNA=short
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what is a DNA molecule
A double helix with 2 polynucleotide chains held together by hydrogen bonds between specific complementary base pairs
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what is RNA
A relitavley short polynucleotide chain
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how is the structure of DNA related to its function
sp-backbone: provides strength/rigidity long: so can store lots of info helix:compact double stranded:so replication can occur sc'ly CBP'ing:accurate replication many H bonds: so stable. base seq: can code for amino acids/proteins
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What does semi-conservative replication ensure?
genetic continuity between generations of cells.
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describe the process of DNA replication (5marks)
Double helix unwinds. Hydrogen bonds between complementary bases in the polynucleotide strand break. DNA helicase hydrolyses H bonds and separates the strand. new DNA nucleotides are attracted to exposed bases on template strands.
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Complementary base pairing- A--T , G---C . DNA polymerase joins adjacent nucleotides together using condensation reaction, forming SUGAR-PHOSPHATE BACKBONE JOINED BY PHOSPHODIESTER BONDS
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why is the replication of DNA described as semi-conservative?
each new DNA molecule contains one strand from original molecule and one new strand. Also each strand copied acts as a template
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What did Meslon and Stahl do
grew E Coli on medium which the nitrogen atoms were the heavy isotope 15N. The bacteria were then transferred into a medium in which nitrogen was normal 14N
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how did this prove semi conservative replication?
results in DNA molecules with both hybrids and new light DNA molecules therefore proves
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Hershey & Chase how did they prove that proteins were not heraditary
35S used to label proteins- and none was found in next generation of phages
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How did they prove DNA is hereditary
32P was used to label DNA- was found in next generation
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What are ribosomes formed from


RNA and proteins

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similarities of DNA and RNA


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Card 4


differences of DNA and RNA


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Card 5


what is a DNA molecule


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