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Understanding DNA Structure and Function

Learn about the structure of DNA, its importance as the blueprint of life, and its role in protein synthesis. Discover Watson and Crick's double helix model, the composition of DNA, and the pairing of nitrogenous bases. Explore the significance of hydrogen bonds and Chargraff's rule. Gain fascinating insights into the abundance and size of DNA.

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Understanding DNA Structure and Function

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  1. Warm Up Go to EDPUZZLE and Complete the DNA Structure video and questions (use your headphones)

  2. Think back to the first unit we learned about in class…. What Biomolecule is DNA associated with? What does DNA do for us as organisms?

  3. The Structure of DNA

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

  5. Watson & Crick’s Model Watson and Crick are the two scientists credited with discovering the shape of DNA (Double Helix)

  6. Why do we study DNA? We study DNA for many reasons, - its central importance to all life on Earth, • medical benefits such as cures for diseases, better food crops, and forensic science.

  7. Our genes are on our chromosomes. Chromosomes are coiled up strands of DNA. Chromosomes and DNA

  8. The Shape of the Molecule The basic shape of DNA = two complimentary strands running in the 5 prime to 3 prime direction shaped like a twisted ladder (DOUBLE HELIX)

  9. The Double Helix Molecule If DNA is a Polymer......What is the monomer of DNA?

  10. One Strand of DNA phosphate • The backbone of the molecule is alternating phosphates and deoxyribose sugar • The teeth are nitrogenousbases. deoxyribose bases

  11. 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

  12. One Strand of DNA nucleotide • One strand of DNA is a polymer of nucleotides. • One strand of DNA has millions of nucleotides.

  13. 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

  14. Four nitrogenous bases DNA has four different bases: • Cytosine C • Thymine T • Adenine A • Guanine G

  15. 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.

  16. 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.

  17. Two Stranded DNA • Remember, DNA has two strands that fit together something like a zipper (double helix). • The teeth are the nitrogenous bases but How do they stick together?

  18. 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 (so they can be broken later) but there are millions and millions of them in a single molecule of DNA.

  19. 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

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

  21. The earth is 150 billion m or 93 million miles from the sun. DNA by the Numbers • 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.

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