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DNA Structure & Function

DNA Structure & Function. You Tube Index. DNA Structure (in order of usefulness) DNA Structure http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter14/dna_structure.html Good (factual, but dry) http://www.youtube.com/watch?v=tknYrU98rBk&feature=fvwrel

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DNA Structure & Function

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  1. DNA Structure & Function

  2. You Tube Index DNA Structure (in order of usefulness) • DNA Structure • http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter14/dna_structure.html • Good (factual, but dry) • http://www.youtube.com/watch?v=tknYrU98rBk&feature=fvwrel • Structure & Prot synthesis • http://www.youtube.com/watch?v=FUA6_Ucw3i4 For history of discovery of DNA and structure see the Powerpoint “DNA History”

  3. Watson & Crick (credited with discovery of STRUCTURE of DNA, though their work relied heavily on the work of others)

  4. !!! DNA Functions • Carries genetic code for life processes • Can replicate to continue life… • Lengths of DNA (genes) code for production of proteins that are • structural • functional • & are 95% of human body!

  5. !!! DNA Packaging

  6. Role of DNA Terms(over the course of this AS & others you will understand all of these terms) • Genome – all the DNA in a cell • Genes – sections of DNA coding for the production of proteins • Chromosomes - • Chromatid • Nucleus - • Nuclear Membrane • Chromatin • DNA • Nucleotides - the repeating unit of DNA • Protein • mRNA • Prokaryote – cells / organisms without a nucleus • Eukaryote – cells / organisms with a nucleus • Protein synthesis – process where protein is manufactured • Mitochondria – organelle (“little organ”) in a cell where energy (ATP) is produced • Cytoplasm • Enzymes • Metabolism • Cell division • Centromere

  7. !!! Nucleic Acids • Two types: • DNA – Deoxyribose nucleic acid (location: nucleus) • RNA – Ribose nucleic acid (location: nucleus + cytoplasm) • Made of repeating units: nucleotides • Nucleotide made of: • Nitrogen base • A 5-carbon sugar (deoxyribose in DNA, ribose in RNA) • Phosphate group

  8. Sweet Difference

  9. !!! DNA Structure • The two strands are “anti parallel” • One strand runs from 3’ to 5’ the other 5’ to 3’

  10. DNA Structure • Shape: double helix (like a twisted ladder)

  11. !!! DNA Structure In RNA the base U (Uracil) replaces thymine • 4 bases: • A – Adenine T – Thymine • G – Guanine C – Cytosine • “Rungs” - Bases held together by hydrogen bonds • A pairs with T (two bonds) • G pairs with C (three bonds) • “Backbone” • Sugars joined to phosphates * by “phosphodiester” bonds! • Complementary vs template • Since you find a C opposite a G… etc the second strand is said to be complementary to the first. • And: the first strand can be used as a template to make a new complementary strand

  12. * Pyrimidines vs Purines • The “pyrimidine bases” are: • C & T (one ring structure) • The “purines” are: • A & G (double ring structure) To remember: purines = two rings

  13. Length of DNA in organisms • Only 4 bases BUT one DNA molecule = millions of bases long • Human: 6 billion base pairs • Bacteria: ~ 4.3 million bases • Viruses…..

  14. ΦX174 Bacteriophage DNA Sequence Bacteriophage = virus affecting bacteria 9 genes, each codes for one protein. Genes overlap, one genes is highlighted. Human genome = 1 million times longer

  15. How much DNA in humans? • ~ 100,000,000,000,000 cells in the human body • 2m of DNA in each cell (3-5cm per chromosome) • DNA length in kilometres: • 200,000,000,000 km • How many times to the moon? (moon = 184,000km) • 1,086,957 times • How many times to the sun & back? (= 300,000,000km) • 667 times

  16. DNA Structure END

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