Chapter 12  FROM DNA TO PROTEINS

1. DOWNLOAD an Adobe Acrobat version of the chapter outline
2. Textbook website:
   1. outline, quiz, and flash cards: select from resources for chapter 12.
3. STARR AN TAGGART 10th edition website:
   1. outline, quiz, and flash cards: select from resources for chapter 13
4. On-Line Biology Book by M. J. Farabee 
   1. Protein Synthesis
5. Kimball's Biology Pages
   1. One Gene, One Enzyme 
   2. Transcription of DNA  from Kimball's Biology Pages
   3. The Genetic Code
   4. Translation of messenger RNA from Kimball's Biology Pages
   5. Mutations
   6. Transposons: Mobile DNA
6. The Biology Project  an interactive online resource for learning biology, developed at The University of Arizona
   1. Nucleic Acid Problem Set
7. MIT Biology Hypertext 
   1. The Central Dogma
   2. Transcription
   3. Translation
   4. Mutation
   5. Problems
8. North Harris College Gene Regulation
9. Mendel Web
10. Transcribe and Translate a Gene from the Genetic Science Learning Center, University of Utah
11. Discover how Proteins Function from the Genetic Science Learning Center, University of Utah
12.  

FROM DNA TO PROTEINS Chapter

Beyond Byssus [Fig. 14.1]

• Replication: DNA --> DNA 
• The CENTRAL DOGMA of Biology
  •  from genes to proteins 
  • Transcription: DNA --> mRNA 
  • Translation: mRNA (+ tRNA + ribosome) --> polypeptide 

14.1 – MOST GENES CARRY INFORMATION FOR MAKING PROTEINS 

1. Garrod (1923): "Inborn Errors of Metabolism" [Fig. 14.2] 
2. Beadle and Tatum (1940's)
   1. one gene, one enzyme
   2. mutant strains of Neurospora[Fig. 14.3] 
3. Gel Electrophoresis [Fig. 14.4]: Linus Pauling and Harvey Itano 
   1. normal versus sickle cell hemoglobin  
4. One Gene-One Polypeptide Hypothesis
   1. genes encode information for amino acid sequences [Fig 14.5] 

14.2 – HOW IS DNA TRANSCRIBED INTO RNA? 

1. RNA: usually single stranded; sugar is ribose; uracil instead of thymine [fig. 14-6] 
2. The Three Classes of RNA 
   1. mRNA: messenger RNA; copies genetic information from DNA (transcription); and carries information to ribosome 
   2. rRNA: comprsses ribosomes, along with proteins; helps assemble proteins 
   3. tRNA: transfers amino acids to ribosomes for translation. 
3. Transcription [figs. 14.7, 14.8] 
   1. information transcribed from DNA to mRNA
      1. complimentary sequence
      2. RNA polymerase
      3. promoter
   2. either strand can be transcribed
      1. sense strand
      2. antisense strand
4. Finishing Touches on mRNA Transcripts 
   1. The 5' end is capped with a special nucleotide with a methyl group and phosphates
   2. a "poly-A tail" of about 100—200 molecules of adenylic acid is added to the 3' end
   3. split genes [fig 14.9]
      1. precursor mRNA
      2. introns
      3. exons

14.3 – DECIPHERING THE GENETIC CODE 

1. Genetic Code
   1. universal [fig 14.10; 14.11]
   2. DNA: code (genotype)
   3. mRNA: codons
      1. 64 triplets [fig. 14.11] 
      2. one start; 3 stops; 20 amino acids
      3. code is degenerate
   4. 3. tRNA: anticodon (3' 5') 

14.4 – TRANSLATION 

1. Introduction 
   1. Ribosomes: two subunits that join together when protein synthesis begins [fig. 14.13]
   2. Transfer RNA [fig. 14.12]
2.  Translation Process [Fig. 14.14]
   1. Chain initiation
   2. chain elongation [fig. 14.9]
   3. chain termination
3. What Happens to the New Polypeptides?
   1. Steps 1-3 can be repeated many times on the same mRNA because several ribosomes may be moving along the mRNA at the same time (polysome).

14.5 – DO MUTATIONS AFFECT PROTEIN SYNTHESIS 

1. Gene Mutations 
2.  mutagens
3. Common Mutations [Fig. 14.15] 
   1. point mutation (base-pair substitution mutation) 
      1. silent
      2. missense
      3. nonsense mutation
   2. frameshift mutations
      1. deletion or insertion of one or more DNA bases [fig 14.16]
   3. Moveable Genetic Elements: jumping genes
      1. transposons
      2. Barbara McClintock [Fig 14.17] 

MUTATIONS, GENE PRODUCTS, AND EVOLUTION 

1. human genome: 3 billion nucleotides in a haploid cell (23 chromosomes)

KEY TERMS FOR CHAPTER 11

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