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Gene Expression & Regulation and River Out of Eden by Richard Dawkins - Chapter 11

By biology, From cbs.dtu.dk, Date: 2008-03-12 05:21:09

"And a river went out of Eden to water the Garden."
                          - Genesis 2:10

Brief Outline

1. The Digital River and the flow of Genetic Information
2. Synthesizing Proteins from the Instructions of DNA
3. The Genetic Code
4. RNA: Intermediary in Protein Synthesis
5. Protein Synthesis
6. Mutations in DNA and Their Effects
7. Gene Regulation

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1. The Digital River and flow of Genetic Information:

DNA -> RNA -> protein
This is known as:
The Central Dogma of Molecular Biology


The Relationship between Genes and Proteins

  • Most genes encode the information for the synthesis of a protein
  • The sequence of bases in DNA codes for the sequence of amino acids in proteins
Sense Strand figure
Shown below is an Illustration of the transcription of DNA to RNA to protein which forms the backbone of molecular biology.
Central Dogma of Molecular Biology

LEGEND

  • DNA codes for the production of RNA.
  • RNA codes for the production of protein.
  • Protein does not code for the production of protein, RNA or DNA.
  • The end.
Or in the words of Francis Crick:
Once information has passed into protein, it cannot get out again.
This was taken from Genetech's homepage:
Link to Genetech's Access Excellence site

However, the "Central Dogma" has had to be revised a bit. It turns out that you CAN go back from RNA to DNA, and that RNA can also make copies of itself. It is still not possible to go from Proteins back to RNA or DNA, and no known mechanism has yet been demonstrated for proteins making copies of themselves.

New (revised a bit) Central Dogma


Try it for youself on the "DNA Workshop" (from PBS).

Click HERE for a link to nice historical review of The Central Dogma.

Link to MIT Hypertext on Central Dogma


2. Synthesizing Proteins from the Instructions of DNA

  • Genetic information flows in a cell from:
DNA ->RNA-> Protein
Figure 13_47 from Griffiths et al., 1996
3. The Genetic Code
Figure 10_37
Figure 10_36 from Hartl & Jones, 1998
  • The Genetic Code uses three bases to specify each amino acid
The Genetic Code
4. RNA: Intermediary in Protein Synthesis
  • Transcription produces RNA molecules that are complimentary copies of one strand of DNA
Figure 13-11 from Griffiths et al.
    Animation of TRANSCRIPTION

  • Three types of RNA cooperate in protein synthesis
Table 13_2 from Griffiths et al., 1996

Figure 1_07 from Hartl & Jones, 1998

5. Protein Synthesis
Peptide bond formation Click "Reload" to see the animation
Proteins are made from the "N" (amino) side to the "C" terminus (carboxyl end).

Figure 10_21a from Hartl & Jones, 1998

6. Mutations in DNA and Their Effects
  • Point mutations are changes in a single base
  • Insertion and deletion mutations result from addition or removal of nucleotides
Figure 10_29 from Hartl & Jones
  • Mutations differ in their effects on protein structure and function
  • Mutations provide the raw material for evolution
7a. Gene Regulation in Prokaryotes (bacteria)
Figure 13_48a from Griffiths et al, 1996
7b. Gene Regulation in Eukaryotes
  • Eukaryotic genes consist of DNA segments that code for the amino acid sequence of proteins interrupted by noncoding DNA segments
  • Eukaryotic cells may regulate the transcription of individual genes, large parts of chromosomes, or entire chromosomes
Figure 13:48b from Griffiths et al., 1996


Figure 1_10 from Griffiths et al., 1996