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• Today– Chapter 14 and 16 highlights
• Wed., 30 November– Final exam review – BRING YOUR QUESTIONS!– Instructor evaluations
• Mon., 12 December, 2:15-4:15pm in C317– Final Exam
• [email protected]• Office: B-203 (by appointment)
1) DNA is transcribed to form RNA
2) RNA is translated to form polypeptide chains, which fold to form proteins
DNA to Proteins
3 Classes of RNAs
• Messenger RNA (mRNA)
– Protein-building instruction
• Ribosomal RNA (rRNA)
– Major component of ribosomes
• Transfer RNA (tRNA)
– Delivers amino acids to ribosomes
Base Pairing during Transcription
DNA
DNA DNA
RNAG C A T
C G T A
G C A U
C G T A
base pairing in DNA replication base pairing in transcription
Transcription• Small DNA stretch = template
• RNA polymerase = enzyme
• Product = 1 RNA strand
transcribed DNA winds up again
DNA to be transcribed unwinds
mRNAtranscript RNA
polymerasePROTEIN INSTRUCTIONS
Genetic Code
• 64 base triplets
• Triplets = codons– 61 = amino acids
– 3 = stop
Figure 14.7Page 230
tRNA Structure
codon in mRNA
anticodon
amino acid OH
amino-acidattachment site
Figure 14.8Page 231
BRINGS AMINO ACIDS TO RIBOSOMES
Overview
Transcription
Translation
mRNA rRNA tRNA
Mature mRNA transcripts
ribosomal subunits
mature tRNA
Polymerase Chain Reaction(PCR)
Double-stranded DNA to copy
DNA heated to 90°– 94°C
Primers added to base-pair with ends
Mixture cooled; base-pairing of primers and ends of DNA strands
DNA polymerasesassemble new DNA strands
Figure 16.6Page 256
Stepped Art
Polymerase Chain Reaction
Figure 16.6Page 256
Stepped Art
Mixture heated again; makes all DNA fragments unwind
Mixture cooled; base-pairing between primers and ends of single DNA strands
DNA polymerase action again doubles number of identical DNA fragments
Gel Electrophoresis
• DNA placed at one end of a gel
• A current is applied
• DNA molecules (-) move to + end
• Small molecules faster than large
Nucleotides for Sequencing
• Standard nucleotides (A, T, C, G)
• Modified versions– Fluoresce
– Stop DNA synthesis
Recording the Sequence
T C C A T G G A C CT C C A T G G A C
T C C A T G G A
T C C A T G G
T C C A T G
T C C A T
T C C A
T C C
T C
T
electrophoresisgel
one of the many fragments of DNA migratingthrough the gel
one of the DNA fragmentspassing through a laser beam after moving through the gel
T C C A T G G A C C A
•DNA placed on gel
•Fragments move by
size
•Pass through laser
beam
•Color of each fragment
is recorded on printout
Figure 16.8Page 258
Information
• Today– Chapter 14 and 16 highlights
• Wed., 30 November– Final exam review – BRING YOUR QUESTIONS!– Instructor evaluations
• Mon., 12 December, 2:15-4:15pm in C317– Final Exam
• [email protected]• Office: B-203 (by appointment)