1 / 28

The Structure of DNA

The Structure of DNA. Chromosomes are made up of a chemical called DNA. They contain genes. Chromosomes and DNA. Genes. Instructions to build proteins. Examples: gene for hitchhiker’s thumb, widow’s peak, tongue-rolling… Humans have over 30,000 genes encoded in their genome.

christinaz
Download Presentation

The Structure of DNA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The Structure of DNA

  2. Chromosomes are made up of a chemical called DNA. They contain genes. Chromosomes and DNA

  3. Genes • Instructions to build proteins. • Examples: gene for hitchhiker’s thumb, widow’s peak, tongue-rolling… • Humans have over 30,000 genes encoded in their genome.

  4. Why do we study DNA? We study DNA for many reasons, e.g., • its central importance to all life on Earth, • medical benefits such as cures for diseases, • better food crops.

  5. DNA • DNA is often called the blueprint of life. • In simple terms, DNA contains the instructions for making proteins within the cell.

  6. The earth is 150 billion m or 93 million miles from the sun. DNA by the Numbers • Each cell has about 2 m of DNA. • The average human has 75 trillion cells. • The average human has enough DNA to go from the earth to the sun more than 400 times. • DNA has a diameter of only 0.000000002 m.

  7. Packaging

  8. Packaging

  9. The Shape of the Molecule • DNA is a very long polymer. • The basic shape is like a twisted ladder or zipper. • This is called a double helix.

  10. The Double Helix Molecule • The DNA double helix has two strands twisted together. http://www.youtube.com/watch?v=4LlBAVhhd-8

  11. One Strand of DNA nucleotide • One strand of DNA is a polymer of nucleotide.

  12. Four DNA nucleotides • Cytosine C • Thymine T • Adenine A • Guanine G

  13. Two Stranded DNA • Remember, DNA has two strands that fit together something like a zipper. • The teeth are the nitrogenous bases but why do they stick together?

  14. O N C N N C C C N N C N N C O C C N C Hydrogen Bonds • The bases attract each other because of hydrogen bonds. • Hydrogen bonds are weak but there are millions and millions of them in a single molecule of DNA. • The bonds between cytosine and guanine are shown here with dotted lines

  15. O N C O C C C N C N N C C C N N C C N Hydrogen Bonds, cont. • When making hydrogen bonds, cytosine always pairs up with guanine • Adenine always pairs up with thymine • Adenine is bonded to thymine here

  16. Discovery of DNA Structure • Erwin Chargaff showed the amounts of the four bases on DNA (A,T,C,G) • In a body or somatic cell: A = 30.3% T = 30.3% G = 19.5% C = 19.9% Adapted from cmassengale

  17. C T A G Chargaff’s Rule: Adenine and Thymine always join together A T Cytosine and Guanine always join together C G

  18. Rosalind Franklin

  19. Watson & Crick’s Model

  20. EXIT SLIP! http://www.youtube.com/watch?v=FUA6_Ucw3i4&feature=related

  21. Hip Hip Hooray • Blame it on the DNA

  22. O -P O O -P O O -P O O O O O O O C C ribose ATP Nucleotides Nitrogenous base One deoxyribose together with its phosphate and base make a nucleotide. O Phosphate C C C Deoxyribose O

  23. N N C N C C C N N C Two Kinds of Bases in DNA N • Pyrimidines are single ring bases. • Purines are double ring bases. N C O C C N C

  24. O N N N C C N C C C C N N N C N C C Guanine Adenine C N N Adenine and Guanine are purines • Adenine and guanine each have two rings of carbon and nitrogen atoms.

  25. N O N N C C O C C O C C C N C N C thymine cytosine Thymine and Cytosine are pyrimidines • Thymine and cytosine each have one ring of carbon and nitrogen atoms.

  26. DNA Replication • http://www.johnkyrk.com/DNAreplication.html

More Related