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REPLICATION. DNA. DNA. TRANSCRIPTION. mRNA. TRANSLATION. amino acids. protein !. Transmission of Information. SUMMARY. http://www.youtube.com/watch?v=NJxobgkPEAo http://www.youtube.com/watch?v=D5vH4Q_tAkY http://www.youtube.com/watch?v=d1UPf7lXeO8

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Presentation Transcript
transmission of information

REPLICATION

DNA

DNA

TRANSCRIPTION

mRNA

TRANSLATION

amino acids

protein !

Transmission of Information
  • SUMMARY
slide3

http://www.youtube.com/watch?v=NJxobgkPEAo

  • http://www.youtube.com/watch?v=D5vH4Q_tAkY
  • http://www.youtube.com/watch?v=d1UPf7lXeO8
  • http://www.youtube.com/watch?v=B6O6uRb1D38
  • http://www.youtube.com/watch?v=yJdAxuIA6QM
  • http://www.youtube.com/watch?v=u9dhO0iCLww
transcription
Transcription
  • Copies the DNA code to mRNA
    • DNA unwinds
    • Only 1 strand is transcribed
    • Complimentary base pairing of nucleotides

C-G G-C T-A A-U

    • This pairing forms the mRNA
    • RNA polymerase helps form the new mRNA
      • initiation signal - “start here”
      • termination sequence - “stop synthesis”
transcription1
Transcription

Termination

sequence

mRNA 3’

mRNA 5’

translation
Translation
  • Translation occurs on the ribosomes
    • Ribosome spheres dissociate into 2 parts
    • Each “half” of ribosome is made of...
      • rRNA
      • polypetides (enzymes)
    • 60S unit (larger piece of ribosome)
    • 40S unit (smaller piece of ribosome)
translation1
Translation
  • Translation occurs on the ribosomes
    • mRNA is “stretched out” on ribosome
    • Nucleotides on the mRNA are grouped into 3s to form: “CODONS”
      • each CODON carries a 3 letter code to translate into an amino acid
      • “Anticodons” on tRNA will match-up with the codons
ribosome

60 S

mRNA

codons

UUG

AUG

GCU

AUG

3’

5’

Ribosome

rRNA

rRNA

40 S

AUG – School Starts in August

genetic code
Genetic Code
  • The Genetic Code
    • Broken in 1961 by Marshall Nirenberg and coworkers
    • Made poly-U mRNA and “fed” it to ribosomes
    • The only peptide made was phenylalanine
    • Therefore, UUU codes for Phe
    • Each AA is coded for by a sequence of 3 nucleotides on mRNA = CODON
translation2
Translation
  • 4 STAGES in Protein Synthesis:
    • Activation
    • Initiation
    • Elongation
    • Termination
activation

activated AA

fMET

anticodon

C

A

G

Activation
  • Each AA is activated by reacting with an ATP
  • The activated AA is then attached to particular tRNA... (with the correct anticodon)
elongation
Elongation
  • The new peptide is added on and the whole ribosome “translocates” or moves down one codon.
  • A new “A site” is available for another AA to add.
termination
Termination
  • After the last translocation (the last codon is a STOP), no more AA are added.
  • “Releasing factors” cleave the last AA from the tRNA
  • The polypeptide is complete
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