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DNA

DNA. The Molecule Of Life. DNA Structure. Nucleotides The Backbone Base Pairing The Double Helix Chromosomes Nucleosomes Genes. Nucleotide: the basic molecule of DNA. 3 parts: Nitrogenous base Sugar Phosphate. 5’. 3’. Nucleotides: 4 bases.

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DNA

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  1. DNA The Molecule Of Life

  2. DNA Structure • Nucleotides • The Backbone • Base Pairing • The Double Helix • Chromosomes • Nucleosomes • Genes

  3. Nucleotide: the basic molecule of DNA 3 parts: • Nitrogenous base • Sugar • Phosphate 5’ 3’

  4. Nucleotides: 4 bases The nucleotides in DNA use 4 different bases: • Guanine G • Cytosine C • Adenine A • Thymine T * Just think G-CAT, you know that rapper

  5. Nucleotide Bases: 2 classes Purine: • Adenine • Guanine Pyrimidine • Cytosine • Thymine Purines Pyrimidines

  6. The Backbone • Nucleotides combine by covalent bond between phosphates and sugars

  7. 5’ A single strand of DNA Written as: 5’-ACTGTCAAGGTCGAT-3’ 3’ 3’

  8. Base Pairing Hydrogen Bonds for spontaneously between specific nitrogenous bases Pairing Rule: • Cytosine bonds with Guanine C-G • Thymine bonds with Adenine T-A

  9. Base Pairing

  10. A Double Strand of DNA 5’ 3’ 3’ 5’

  11. How a DNA strand is written 5’ - ATAGGGCCTAGAACCTGG - 3’ 3’ - TATCCCGGATCTTGGACC - 5’ Strands are anti-parallel

  12. Try writing one yourself 3’ - TTAAGCTATGCT - 5’ What is the complementary DNA strand?

  13. Now draw a double strand, including bases and backbones 5’ - ATGC - 3’ Does your diagram have sugars, phosphates, and nitrogen bases? Are the strands anti-parallel? Where are covalent bonds between nucleotides? Where are the hydrogen bonds?

  14. The Double Helix

  15. High Resolution image of Actual DNA molecule

  16. DNA within a Cell • DNA combine with proteins called histones to create structures called chromosomes • Each cell contains many chromosomes, each with a specific DNA sequence

  17. A Nucleosome • DNA strands are tightly wrapped around histone proteins to create a complex known as a nucleosome

  18. Genes • A gene is a specific sequence of DNA nucleotides • The DNA sequence contains the information necessary to build a protein • Each specific gene codes for a specific protein

  19. How much DNA is there? The human genome contains 3 billion base pairs of DNA, about the same amount as frogs and sharks. But other genomes are much larger. A newt genome has about 15 billion base pairs of DNA, and a lily genome has almost 100 billion.

  20. Unravel all the DNA in your body… …and it would stretch to the moon!

  21. Junk DNA • Only a very small percentage of your DNA (1.5%) is actually composed of coding genes, most of it is repetitive sequences or other non-coding sequences • We still don’t know what the other 98.5% of DNA in our cells are for. • We’ve still got a whole lot to learn

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