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DNA: D eoxyribo n ucleic A cid

DNA: D eoxyribo n ucleic A cid. Image from http:// www.pratt.duke.edu. What do you know about DNA?. My 10 year old says “Mom, everyone knows all about DNA.” OK… so what do you know? By the way… I “ googled ” the term DNA and it returned 2.6 MILLION images!.

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DNA: D eoxyribo n ucleic A cid

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  1. DNA: Deoxyribonucleic Acid Image from http://www.pratt.duke.edu

  2. What do you know about DNA? • My 10 year old says “Mom, everyone knows all about DNA.” • OK… so what do you know? By the way… I “googled” the term DNA and it returned 2.6 MILLION images! Image from www.blockbuster.com

  3. The Double Helix • Another image from GATTACA … Image from www.movieforums.com

  4. A=T and G-C • The Double Helix is held together by “Hydrogen Bonding” • Gives the Helix specificity • Chargaff’s Rule (1950): [A] = [T] and [G] = [C] refuted the previously held understanding of the “Tetranucleotide Hypothesis” Images from: The Creative Science Quarterly: www.scq.ubc.ca and http://en.wikipedia.org/wiki/Phoebus_Levene

  5. A Closer Look at the Anatomy of the Double Helix • While the base pairs are holding things together in the middle… • the sugars and phosphates are holding things together along the sides. • The strands in the Double Helix are “antiparallel” The sugar in DNA is “DEOXYRIBOSE” Image from: http://whyfiles.org

  6. Structure : Function • The DNA Double Helix is wound around a set of proteins call “Histones” which allow for efficient packaging of the DNA into Chromosomes • The Chromosomes are then packaged into the Nucleus of the Cell

  7. Replication • The structure of the double helix provides a means for Replication • DNA copied into more DNA… exactly the same • Watson and Crick: 1953 paper in Nature described not only the double helix structure but MORE IMPORTANTLY identified the double helix as a mechanism for replication • The mechanism (“semi-conservative replication” was not proven experimentally until 1957, by Meselson and Stahl. "It has not escaped our notice that the specific pairing that we have postulated immediately suggests a possible copying mechanism for the genetic material."Nature171, 737–738 (1953) Image from healthanddna.com

  8. Transcription • One strand of the DNA is copied into an RNA strand • The RNA strand serves as a messenger (mRNA) that goes out into the cytoplasm to direct the synthesis of the corresponding protein • RNA’s and their function studied in the late 1950’s and well into the 1960’s http://www.dnai.org/timeline/ Image from http://www.le.ac.uk/ge/genie/vgec/he/expression.html

  9. Translation • The RNA is translated into Protein • Proteins are NOT nucleic acids... They are made of amino acids • Notice that the Ribosome (the blob here) is focused on three nucleotides – that is the “CODON” Image from http://www.dorlingkindersley-uk.co.uk

  10. Not to over simplify… • This image shows that Translation occurs outside the nucleus • And that tRNA is involved in the protein synthesis process • REGULATION – or Gene expression can be controlled at many different stages of the process

  11. ? HeLa Cells • Cancer • Uncontrolled cell growth due to errors in regulation • Errors could be in any part of the process • Errors are called Mutations • Mutations can be genetic, environmental (virus, carcinogen, or various forms of energy); damage to the DNA can be cumulative In the case of HeLa, the cervical cancer was caused by a Human Papillomavirus (HPV-18) which integrated itself into a normal gene and then caused five different mutations including “numerical and structural chromosomal aberrations” Image from www.smithsonianmag.org Quote from Cancer Res.59 (1): 141–50

  12. Virus • Virus are nucleic acids – HPV, HIV, polio, herpes, adenovirus (cold) etc… • They are received into a cell where they insert their viral genetics into the cell’s normal routine and take over • New virus are produced, killing the cell, taking over more cells, and wearing down the immune system

  13. Gene Therapy • DNA can be inserted – therapeutically – into a cell in order to cause the cell to synthesize a missing or dysfunctional protein. Gene therapy has been used successfully in clinical trials for Cystic Fibrosis, some eye diseases, lung cancer, melanoma … Still in development

  14. Genetic Engineering(Transgenics) • Insert DNA from one species into another species in order to acquire a new trait or characteristic. • Common today in agriculture for improving yield (anti-pest genes) and marketability (harvest time, shipping, storage, shelf-life)

  15. DNA …

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