DNA Laboratory

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DNA Laboratory

• Building a DNA Model DNA Fingerprinting

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Schedule for Today
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DNA Fingerprinting

• Detects differences between individuals at the
  DNA level
• Uses restriction enzymes that cut DNA at specific
  sequences
• Differences in position of restriction enzyme
  cuts yield different DNA fragment sizes
• RFLP restriction fragment length polymorphism

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Use of the Restriction Enzyme Bam H1
5 G G A T C C 3 3 C C T A G G 5
5 G G A T C
C 3 3 C C T A G
G 5
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Separation of Restriction Fragments by Size
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Gel Electrophoresis
Larger fragmentsmove more slowlysmaller
fragmentsmove more rapidly
Directionof Migration
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Submerging the gel
Pouring the agarose
Loading the gel
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Using the Micropipettor

• Set volume to 35 ul
• Attach a clean tip
• Push plunger to first stop
• Insert tip into liquid
• Release plunger SLOWLY
• Position over well in gel
• Push plunger SLOWLY to second stop to fill
  well
• Discard tip in orange bag

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Model will show Replication, Transcription and
Translation
DNA
(G1 and G2 phases)
RNA
Protein
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Completed Model

• One DNA double helix, two chains of 9 nucleotides
  each
• one chain can have any sequence
• second chain must be complementary
• One chain of mRNA, 9 nucleotides long
• must be complementary to one of the two DNA
  chains (DNA template is 3?5, mRNA is 5?3)
• Three tRNAs with appropriate amino acids attached
• tRNA anticodons must match mRNA codons

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Structure of a Nucleotide
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Link the phosphate of one nucleotide to the sugar
of the next nucleotide to produce a DNA chain.
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ReplicationPair A with T and G with C to
produce the second chain. One chain is
5?3Other chain is 3?5
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DNA polymerase adds nucleotides to the growing
chain in a 5?3 direction.
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Building Your DNA Model
One chain can have bases in any order, the other
chain must be complementary
Your completed model will have two DNA chains,
each with 9 nucleotides.
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Three Types of RNA
DNA
rRNA
mRNA
tRNA
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TranscriptionOne DNA chain is used as a
template. Template is read 3?5RNA is produced
5?3
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RNA polymerase adds nucleotides to the growing
chain in a 5?3 direction.
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Building Your DNA Model
Choose one DNA chain as the template for RNA
Read the template from 3?5 to produce the mRNA
from 5?3
Your completed messenger RNA will have 9
nucleotides.
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Structure of transfer RNA
Anticodon on tRNA recognizes codon on mRNAto
bring amino acid into place.
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Each group of 3 nucleotides on mRNA is a codon.
Codons are read from 5?3. tRNA anticodons, from
3?5 match the codons.
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Read the CODON from 5?3 to determine the amino
acid carried by the tRNA.
Serine
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Building Your DNA Model
Attach 3 bases to the tRNA to form the anticodon
Read the CODON from 5?3 to find the name of the
amino acid
Serine
Your completed model will have 3 tRNAs, one for
each codon in mRNA. Show the name of the amino
acid carried by each tRNA.
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CLEAN UP!

• After pouring gel, fill flask with water and
  return to bath
• Put used tips in the orange bags
• Rinse and dry the gel tray, comb and rubber dams
• Leave buffer in electrophoresis chamber
• After analysis, discard staining sheets and
  agarose gels into trash
• Put all paper clippings into trash
• Make sure the sinks stay clean

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Worksheet

• Attach your completed DNA model inside a
  legal-sized folder
• Complete pages 95-96 from lab manual
• Be sure your instructor checks both of these
  items before you leave the lab