Ch. 16 DNA

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Ch. 16DNA

• DNA the Central Dogma, history, structure
• Replication

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History timeline, people and their
accomplishments

• Mendel (heredity)
• Thomas Hunt Morgan (flies, linkage)
• Griffith (1928) transformation and mice
• Avery and colleagues (1944)
• proposed DNA as the transforming agent
• Chargaff (late 40s-early 50s)
• base pairing (AT CG)
• Hershey-Chase (1952) DNA IS hereditary material
• Watson and Crick (1953) (Franklin)
  chemical structure of DNA
• Meselson-Stahl mid 1950s
• DNA Replication details

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Griffith
Transformation
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Hershey / Chase (the hereditary material is not
a protein)
Radio-active P and S
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Whose rule? A-T C-G
Purine? Pyrimidine?You have 6 billion pair in
every cell!
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Hows it all fit?

• DNA coiling Lets see it!

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Chargaffs Rule

• Purines (A, G, double rings) always pair with
  Pyrimidines (T, C, single rings)
• A-T, C-G ( in RNA? ____)
• Old AP test question if in a cell the DNA bases
  are 17 As then what are the s of the other
  bases?
• CUT your PY or Pure Silver (Ag)

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DNA Replication SEMICONSERVATIVE MODEL How did
they (Meselson-Stahl) prove this? FIG 16.10
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KNOW Steps of ReplicationEnzymesLeading and
Lagging strands Okazaki FragmentsAnti-parallel
Video
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Bubbles Replication forks, simultaneous
replication Eukaryotes - multiple origins of
replication Prokaryotes have one
Semi-conservative
This process is fueled bynucleoside
triphosphates
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DNA is made from 5 to 3 and it is read from
3-5. The 3 end is the end which elongates
(grows) Why is this direction important to
consider in Replication?
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What do the terms 5 and 3 mean?
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Leading Lagging strands, made 5-3 Okazaki
fragments (are of the lagging strand)
ENZYMES helicase, DNA Polymerase, ligase
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• Enzymes
• HelicaseSingle strand binding
  proteinsPrimase (RNA Primer)DNA
  PolymeraseLigase
• Nuclease and DNA Polymerase (both are repair
  enzymes)

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Lets see this in Action

• Leading Strand (Nobelprize.org)
• Lagging Strand (Nobelprize.org)
• Overall (wiley)
• Overall 3D view (wehi.edu.au or
  dnai.org) (Youtube has a music version)

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Telomeres (Ch.16)Unfilled gap left at the ends
of the DNA strands due to the use of RNA
primersEventual shortening of DNA over
time Dolly, cancer, HeLa cells (telomerase
fig16.19)
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Enzyme Telomerase extends the (3) long strand
so the 5 strand can finish. WOW! ? ? ? Where is
telomerase naturally found?
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DNA from a single skin cell, if straightened out,
would be about six feet long but invisible. Half
a gram of DNA, uncoiled, would stretch to the
sun. Again, you couldn't see it.
http//www.pixar.com/featurefilms/nemo/images/inde
x_lwide.jpg
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Story Time!! (Due Tuesday Nov. 6)

• Select a figure, process, topic, or high level
  vocabulary word from chapter 16 or 17.
• Your job is to make a poster of your selected
  topic.
• The poster should be kid-friendly as to say an
  intelligent 8-10 year old would be able to
  understand it yet make sure that all information
  communicated is true to the text.
• - Finally, you may not use English, do the best
  you can, ask friends, relatives, teachers, etc
  for help if necessary.
• Potential topics include but are not limited to
  the following..
• Experiments that identified DNA as the genetic
  material, DNA Structure, DNA Replication,
  Telomers and telomerase, Transcription,
  Modification of RNA, Translation, Mutations.

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Ch.17 One gene/One polypeptide
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Define transcription and translationCompare
Prokaryotic and Eukaryotic cellsvideo
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• (21 different AAs)
• mRNA code
• Ave. protein is 400AA long
• Titin is 30,000AA long! (this is _____
  nucleotides?)

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• DNAtriplets
• RNAcodons
• 5 to 3
• Pre-mRNA (primary transcript)

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• Promoter TATA Box
• Transcription factors
• RNA poly-merase
• Transcription initiation complex
• Movie

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Finishing the pre-mRNA
Introns (intruding) spliced out Exons kept,
will be Expressed in the cell
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• snRNPs identify introns
• Introns are cut out at a Spliceosome
• Final mRNA has only genes that will be
  tran-scribed in cellno junk genes
• video

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• Translation
• The production of polypeptides
• On a Ribosome
• tRNA, transfer RNA carries in the amino acids to
  the ribosome (transfers the A.A)

Read 5 to 3
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(No Transcript)
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• A P E
• Aminoacyl-tRNA synthetase
• Peptidyl tRNA binding site
• Exit
• Video
• Movie

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(No Transcript)
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Termination of the translation
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Translation of many polypeptide chains at once
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The signal mechanism signal peptides
Free or bound ribosomes?
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• Coupled transcription and translation

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One base difference out of 574 Amino acids (1722
bases)
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The wrong protein
Nothing formed
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(No Transcript)
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• Happy Homecoming (again!)
• Have fun, be safe

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(No Transcript)
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Repairing mistakes