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NadiaA

DNA
LO:
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To describe the basic structure of DNA and explain how this is related to its twin functions of
reproducing and storing biological information
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g
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Experiment
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Used test tubes instead of mice
Used enzymes to remove cell components one by one to see if transformation would still
occur e
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DNase, RNase, Protease
Possible contaminants of DNA; RNA, Protein
So to find out which was the genetic material, they used RNase, protease, DNase to treat
bacteria one by one
With RNase and protease transformation occurred
When DNase was used, the R strains did not change to LIVE S strain- transformation did not
occur- Thus DNA is the transferring medium

See http://www
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org/17/animation
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youtube
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They worked out the X ray crystal
structure produced by DNA via x-ray crystallography e
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the structure is too large to be single
strand
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e
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g
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CATGCATCA

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CAT, ATG, TGC (overlapping)
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CAT, GCA, TCA (non-overlapping)

Start codon- AUG (methionine) ALWAYS aka ATG in DNA transcript
Stop Codons: UAA, UAG, UGA- terminate translation aka TAA,TAG,TGA in DNA transcript
Genetic code is universal-all organisms use basic genetic code
5 primer to 3 primer end ALWAYS
The third base position is the ‘wobble’ position- a change to the last base usually does not
cause the change in the amino acid
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1 Sickle cell anaemia
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Amino acid at position 6 is hydrophilic in normal erythrocytes
Amino acid at position 6 is hydrophobic in sickle cell anaemia cells
A mutation caused this
All of the other amino acids in the sequence remain correct and unaffected – it is only
position 6 that is affected!
Remember there is no DNA in erythrocytes as
Dysfunctional proteins: E
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2 cystic fibrosis
there is no nucleus, so you sequence the DNA
from another cell of the patient for the beta
Normal epithelial cells have a channel-forming
globin protein
protein
They produce an abnormal protein that simply
lacks the necessary amino acid at position 508

Refer to the table of bases and identify the amino
acid that the dysfunctional sequence produced!

There is a missing triplet codon- deletion
Thus the channel-forming protein is absent from
their membranes

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