DNA and RNA

1
DNA and RNA

• BIOL 100
• 22 October 2009

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Fig 10.3 p. 195

• Deoxyribonucleic acid (aka DNA)
• Nucleotide
• C5 Sugar (deoxyribose)
• Phosphate group
• C/H/O/N base
• Purines A G
• Pyrimidines C T

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Fig 10.4 p. 196

• The Double Helix
• Rungs of twisted ladder are base pairs
• A-T
• C-G
• Uprights are sugar/ phosphate sequences

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Fig 10.8 p. 199

• Base Pairs
• Bond by hydrogen bonds
• A-T 2
• G-C 3
• Both pairs are purinepyrimidine

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Three Processes to Examine

• Replication
• DNA copies itself inside nucleus
• Transcription
• DNA makes RNA inside nucleus
• Translation
• RNA makes protein ribosomes of ER, in cell
  cytoplasm

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Fig 10.20 p. 211

• Replication
• DNA opens up
• Each side is a template for making two copies of
  original
• Each is half original, half new
• Occurs in all chromosomes at same time before a
  cell divides

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Fig 11.6 p. 222

• Transcription and Translation
• Copy (in same language) and Convert (to another
  language)
• Former in cell nucleus, latter on ER in cytoplasm

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The Secret of Life

• DNA ? RNA ? Protein
• Q Why so important?
• A Because proteins
• control what gets into and out of cells
• include some types of hormones
• are important structural molecules and
• include ENZYMES, the biological catalysts that
  control cellular activities.

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Fig 5.13 p. 105

• For example, it takes five enzymes (hence five
  genes in the cells DNA) to convert threonine to
  isoleucine
• Organisms turn genes on and off as situation
  demands

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Fig 11.8 p. 224

• Transcription
• Involves only short portion of DNA on a
  chromosome, only along one side
• DNA closes back together following transcription
  of RNA molecule, which exits cell nucleus

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Three Types of RNA

• rRNA Structural portion of the ribosome, the
  anchor for translation on the ER
• mRNA Contains code for amino acid sequence, in
  codon units
• tRNA Carrier of an individual amino acid,
  opposite its anticodon

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Fig 11.4 p. 221

• mRNA
• Long series of codons
• Start codon AUG
• Stop codon UGA, UAA, or UAG

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Fig 11.12 p. 229

• tRNA
• Anticodon below
• Corresponding amino acid attached at top

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Fig 11.3 p. 221
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Fig 11.13 pp. 230-231

• Growing a protein in translation
• Start at AUG start codon, proceed to stop codon

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Fig 11.14 p. 232

• Overview of the Secret of Life
• DNA?RNA?Protein
• Intron junk (?) segment of mRNA transcript
  cut out prior to translation