Summary: Medical Genomics

Read the summary and the most important questions on Medical Genomics

• 2 Lecture 2 - Timeline of genome sequencing

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• Why should the central dogma maybe be reformulated?

  - Because it implies that RNA is always and only used as a temporary information carrier,
  - and because there is also reverse information flow possible

• What are two important discoveries in the field of genomics?

  - Sanger sequencing
  - PCR technique

• Why can G-banding not be used to detect mutations?

  The resolution is not high enough

• How is it then possible to detect mutations?

  By sequencing the gene

• In the Sanger sequencing method, polymerase is used to generate a new strand. What is different in the Sanger method compared to what happens in nature, and what is it useful for?

  - In the Sanger method, di-deoxyribonucleotides are added,
  - which prevent strand extension at the 3' end

• What is the result of the use of di-deoxyribonucleoside triphosphates (ddNTPs)?

  You get strands of different lengths, with a radioactive label added to the ddNTPs, so that you can get the total sequence of the piece of DNA

• What kind of progress is made in the use of the Sanger sequencing method soon after its invention?

  4 colours are used, so that the difference between A, T, C, and G can be visible (before, they needed to do the reactions for the different bases separately)

• Why was PCR (which was just developed) needed for this 4-colour Sanger sequencing method?

  For this method, you needed a lot of DNA copies

• What are the 3 steps of PCR?

  1. Denaturation
  2. Annealing
  3. Elongation (copying of the DNA with polymerase)

• How does the number of DNA copies grow over time in a PCR reaction?

  There is exponential amplification.