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DNA – life’s code

Learn about the significance of DNA in controlling genetic traits and producing proteins. Explore the structure of DNA, including nucleotides and nitrogen bases. Discover how DNA is packaged and replicated, and the process of protein synthesis through transcription and translation.

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DNA – life’s code

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  1. DNA – life’s code molecule that makes up genes and determines the traits of all living things

  2. Importance of DNA • Controls by: • producing proteins • Proteins are important because • All structures are made of protein • Skin • Muscles • Bones • All actions depend on enzymes (special kind of protein) • Eating • Running • Thinking • All life activities • Structure contains the complete instructions for making all proteins

  3. DNA Structure • Stands for deoxyribonucleic acid • Double helix = twisted ladder = linked nucleotides

  4. DNA Structure - nucleotide • Made of 3 things: • Deoxyribose • Phosphoric acid • Nitrogen bases

  5. DNA Structure – nitrogen bases • Four types: • Adenine • Cytosine • Guanine • Thymine • A nucleotide is named for the nitrogen base it contains

  6. Linking Nucleotides • Nucleotides join together to make DNA – complementary base pairing • Adenine fits with Thymine • A – T • Cytosine fits with Guanine • C – G

  7. How DNA is packaged

  8. Figure 12-10 Chromosome Structure of Eukaryotes Human cells contain over one meter of DNA! How? Section 12-2 Nucleosome Chromosome DNA double helix Coils Supercoils Histones Wrapped around proteins (histones and nucleosomes) Go to Section:

  9. Interest Grabber Section 12-2 • A Perfect Copy • When a cell divides, each daughter cell receives a complete set of chromosomes. This means that each new cell has a complete set of the DNA code. Before a cell can divide, the DNA must be copied so that there are two sets ready to be distributed to the new cells. Go to Section:

  10. Interest Grabber continued Section 12-2 1. On a sheet of paper, draw a curving or zig-zagging line that divides the paper into two halves. Vary the bends in the line as you draw it. Without tracing, copy the line on a second sheet of paper. 2. Hold the papers side by side, and compare the lines. Do they look the same? 3. Now, stack the papers, one on top of the other, and hold the papers up to the light. Are the lines the same? 4. How could you use the original paper to draw exact copies of the line without tracing it? 5. Why is it important that the copies of DNA that are given to new daughter cells be exact copies of the original? Go to Section:

  11. Section Outline Section 12-2 • 12–2 Chromosomes and DNA Replication A. DNA and Chromosomes 1. DNA Length 2. Chromosome Structure B. DNA Replication 1. Duplicating DNA 2. How Replication Occurs Go to Section:

  12. DNA Replication • Making a chromosome copy • One strand  two identical strands • Steps: • DNA “unzips” • Free nucleotides attach to complementary bases • Bonds form between nucleotides creating two identical strands

  13. Figure 12–11 DNA Replication Section 12-2 Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork Nitrogenous bases New strand Original strand Go to Section:

  14. DNA replication • http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf

  15. http://www.wwnorton.com/college/biology/discoverbio3/full/content/ch12/animations.asphttp://www.wwnorton.com/college/biology/discoverbio3/full/content/ch12/animations.asp http://www.youtube.com/watch?v=zdDkiRw1PdU&feature=related

  16. RNA vs. DNA

  17. Concept Map Section 12-3 RNA can be Messenger RNA Transfer RNA also called which functions to also called which functions to Bringamino acids toribosome tRNA mRNA Carry instructions from to DNA Ribosome

  18. Protein Synthesis • Make proteins • Two steps: • Transcription: copying your DNA (genes) into messenger RNA (mRNA). • Translation: turning messenger RNA (mRNA) into proteins-proteins make up cells.

  19. Transcription Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNApolymerase DNA RNA

  20. http://www.youtube.com/watch?v=OtYz_3rkvPk

  21. The Genetic Code Section 12-3 :

  22. Translation Nucleus Messenger RNA Messenger RNA is transcribed in the nucleus. mRNA Lysine Phenylalanine tRNA Transfer RNA The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon. Methionine Ribosome Start codon mRNA :

  23. Translation (continued) The Polypeptide “Assembly Line” The ribosome joins the two amino acids—methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids. Growing polypeptide chain Ribosome tRNA Lysine tRNA mRNA Completing the Polypeptide The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain. mRNA Translation direction Ribosome

  24. Messenger RNA (mRNA) copies DNA and DNA reforms ladder DNA Splits In nucleus “Unzipping” Transfer RNA (tRNA) copy mRNA and make proteins Travels to ribosome Transcription Translation

  25. http://www.youtube.com/watch?v=B6O6uRb1D38

  26. Transcription Animation

  27. Translation

  28. Gene Mutations:Substitution, Insertion, and Deletion Section 12-4 • Point mutation- mutations that affect one nucleotide; generally change one amino acid in a protein (ex: substitution) • Frameshift mutations (Insertion and Deletion) cause much bigger changes since the sequence is read in 3 base codons, everything is now moved over one spot Insertion Deletion Substitution Go to Section:

  29. Figure 12–20 Chromosomal Mutations Section 12-4 Deletion Duplication Inversion Translocation - Involve changes in the number or structure of chromosomes - May change the location of genes and even the number of copies of some genes Go to Section:

  30. Typical Gene Structure Section 12-5 Promoter(RNA polymerase binding site) Regulatory sites DNA strand Start transcription Stop transcription A typical gene includes start and stop signals, with the nucleotides to be translated in between Go to Section:

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