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DNA: A Look Back

DNA: A Look Back. Contents of the Nucleus. DNA vocab. Deoxyribonucleic acid Chromosomes Chromatin Genes. DNA Structure. What is the structure called?. Building blocks of DNA. What are the building blocks of DNA? What are the building blocks made of? (3 parts).

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DNA: A Look Back

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  1. DNA:A Look Back

  2. Contents of the Nucleus

  3. DNA vocab • Deoxyribonucleic acid • Chromosomes • Chromatin • Genes

  4. DNA Structure • What is the structure called?

  5. Building blocks of DNA • What are the building blocks of DNA? • What are the building blocks made of? (3 parts)

  6. How do they fit together? • What is the significance of the order of the nitrogenous bases?

  7. Try “replicating” this single strand of DNA

  8. DNA --> Chromosomes • http://www.youtube.com/watch?v=E8NHcQesYl8&mode=related&search=

  9. Human set of Chromosomes Fruit fly Chromosomes - only 8! • What are chromosomes? • What do they store? • How many do we have? • Where did they come from?

  10. Genes • WHAT are they? • WHERE are they?

  11. Enzymes • WHAT are they? • What do they do? • Why do our DNA molecules store the instructions to make them?

  12. Genetic Material: DNA vs RNA - compare and contrast.

  13. RNA is composed of 3 parts: • Ribose – a smaller sugar than deoxyribose • Phosphate • Nitrogenous Bases -adenine, uracil (instead of thymine), guanine, and cytosine RNA is single-stranded and thus smaller and able to leave the nucleus of the cell

  14. Protein Synthesis

  15. STEPS • Transcription • Translation

  16. Step 1: Transcription • Takes place in the nucleus • Process by which information from DNA is transferred to RNA • DNA uncoils and unzips • The exposed DNA bases are matched up with RNA bases to form mRNA (messenger RNA)

  17. Try transcribing this piece of DNA into mRNA

  18. Step 2: Translation

  19. A U G G G C U U A A A G C A G U G C A C G U U • This is a molecule of messenger RNA (mRNA). It was made in the nucleus by transcription from a DNA molecule. codon mRNA molecule

  20. ribosome A U G G G C U U A A A G C A G U G C A C G U U The mRNA molecule attaches to a ribosome on the rough endoplasmic reticulum.

  21. Amino acid tRNA molecule anticodon U A C A U G G G C U U A A A G C A G U G C A C G U U A transfer RNA molecule arrives. It brings an amino acid to the first three bases (codon) on the mRNA. The three unpaired bases (anticodon) on the tRNA link up with the codon.

  22. U A C C C G A U G G G C U U A A A G C A G U G C A C G U U Another tRNA molecule comes into place, bringing a second amino acid. Its anticodon links up with the second codon on the mRNA.

  23. Peptide bond C C G U A C A U G G G C U U A A A G C A G U G C A C G U U A peptide bond forms between the two amino acids.

  24. C C G U A C A U G G G C U U A A A G C A G U G C A C G U U The first tRNA molecule releases its amino acid and moves off into the cytoplasm.

  25. C C G A U G G G C U U A A A G C A G U G C A C G U U The ribosome moves along the mRNA to the next codon.

  26. C C G A A U A U G G G C U U A A A G C A G U G C A C G U U Another tRNA molecule brings the next amino acid into place.

  27. C C G C C G A U G G G C U U A A A G C A G U G C A C G U U A peptide bond joins the second and third amino acids to form a polypeptide chain.

  28. G U C A C G A U G G G C U U A A A G C A G U G C A C G U U The process continues. The polypeptide chain gets longer. This continues until a termination (stop) codon is reached. The polypeptide is then complete.

  29. The Code: • How do you follow the mRNA code?

  30. Video on Protein Synthesis (includes tRNA) http://www.youtube.com/watch?v=NJxobgkPEAo&mode=related&search=

  31. Try “DECODING” this piece of DNA Code

  32. Read p. 131 of textbook

  33. Where does the protein go from here? • How does it get there?

  34. What are the names of the containers that come off of the ER? • Where do they go?

  35. Exiting the Cell

  36. One Gene = One Protein? • Human genome = approximately 25,000 genes • Number of proteins humans make is approximately 90,000. • NOT SURE HOW THIS CAN BE!

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