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3 Dec

3 Dec. Opener: What does DNA actually do?. Agenda: Intro Unit 5 Transcription Notes Transcription Drawing Bioflix Homework: 4.13 + GQs Participation Quiz Tomorrow. Transcription: The details. Transcription Making a Messenger.

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3 Dec

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  1. 3 Dec • Opener: • What does DNA actually do? • Agenda: • Intro Unit 5 • Transcription Notes • Transcription Drawing • Bioflix • Homework: • 4.13 + GQs • Participation Quiz Tomorrow

  2. Transcription: The details

  3. TranscriptionMaking a Messenger • The enzyme RNA polymerase binds to a gene on a DNA strand (at the promoter site) and opens up the double helix

  4. TranscriptionMaking a Messenger • RNA polymerase moves along the exposed DNA strand, adding complementary RNA nucleotides which form the messenger RNA

  5. TranscriptionMaking a Messenger DNA • As the messenger RNA is assembled, it separates from the DNA template strand pre-mRNA

  6. TranscriptionMaking a Messenger • When the RNA polymerase arrives at stop sequence at end of gene, the messenger RNA strand is released

  7. Post-transcription processing • The pre-mRNA isn’t ready to leave the nucleus, yet… • The cell needs to: • Cut out introns • Add cap and tail

  8. intron = noncoding (inbetween) sequence exon = coding (expressed) sequence There’s junk in those genes! • The pre-mRNA needs to have the junk cut out • exons = the real gene • expressed / coding DNA • introns = the junk • in-between sequence Pre-mRNA

  9. 3' poly-A tail 3' A A A A A mRNA 50-250 A’s 5' cap P P P 5' G More post-transcriptional processing • Need to protect mRNA on its trip from nucleus to cytoplasm • enzymes in cytoplasm attack mRNA • protect the ends of the molecule • add GTP cap • add poly-A tail • longer tail, mRNA lasts longer: produces more protein

  10. …now the mature mRNA is ready to leave the nucleus and go to a ribosome for translation

  11. Transcription Diagram • Nucleus • DNA • RNA polymerase • RNA nucleotides • pre-mRNA • Introns • Exons • Cap • Tail • Mature mRNA Draw a picture of a cell going through the steps of transcription. Make sure to include/label the following:

  12. Look at your drawings to review the steps of transcription

  13. 4 Dec • Opener: • Take out a half sheet of paper for the quiz • Agenda • Participation Quiz • Translation details • Homework: • Read 5.5, 5.6, 5.8 + Guided Reading Questions

  14. Nucleotide Triplets are Translated into Amino Acids

  15. TranslationAssembling the Protein Chain Key Players: Ribosomes- • Organelles where proteins are manufactured • Consists of two subunits • Some attached to rough endoplasmic reticulum, others bound to cytoskeletal fibers

  16. TranslationAssembling the protein chain Key player: tRNA- Transports amino acids to the ribosome

  17. TranslationAssembling the Protein Chain 1. Messenger RNA attaches to the smaller subunit of the ribosome

  18. TranslationAssembling the Protein Chain 2. The first transfer RNA matches the messenger RNA’s first three nucleotides

  19. TranslationAssembling the Protein Chain 3. The larger ribosome subunit joins with the smaller subunit

  20. TranslationAssembling the Protein Chain 4. The second transfer RNA the second dock on the messenger RNA

  21. TranslationAssembling the Protein Chain 5. The backbones of the first two amino acid link

  22. TranslationAssembling the Protein Chain 6. The messenger RNA shifts to the right and the first transfer RNA drops off

  23. TranslationAssembling the Protein Chain 7. The next transfer RNA arrives to add the next amino acid

  24. TranslationAssembling the Protein Chain 8. One by one, triplets are read and the protein chain grows

  25. TranslationAssembling the Protein Chain 9. The final triplet signals “stop”. No transfer RNA fits here.

  26. TranslationAssembling the Protein Chain 10. The ribosome separates and drops off the messenger RNA

  27. TranslationAssembling the Protein Chain 11. For efficiency, the messenger RNA is read by more than one ribosome simultaneously

  28. 6 Dec • Opener: • Take out a half sheet of paper for the quiz • Agenda • Finish Text Questions • Participation Quiz • Protein Synthesis Activity 1 • Protein Synthesis Activity 2 • Transcription/Translation Drawing • Homework: • None

  29. Participation Quiz • What are proteins made of? • What are the 4 RNA bases? • The information in DNA is copied into mRNA in what process? • Where does the process from question #3 take place? • What enzyme is responsible for making mRNA? • Name one thing that has to happen to pre-mRNA to make it mature mRNA

  30. 7 Dec • Opener: • What do you think of when you hear the word “mutation”? • Agenda: • Participation Quiz • Mutations • Mutations worksheet • Homework: • Read and GQs 4.12 • http://www.livescience.com/common/media/video/player.php?aid=27753

  31. 1 2 3

  32. 4 5 6

  33. Natural selection Charles Darwin Where does the Variation come from? There is heritable variation within populations More offspring are born than can survive Leads to a competition for limited resources Differential survival based on adaptation

  34. Mutations can be… • Harmful • Change in amino acid sequence  different protein • Can lead to disease, death • Neutral • Mutation doesn’t change amino acid • Mutation occurs in a section of DNA that does not code for a protein (approx. 95%) • Beneficial • Mutation causes a change that makes the offspring better adapted for survival • Polar bear • Sickle cell disease

  35. 10 Dec • Opener: • Can you tell me an example of a harmless mutation? • Agenda • Review Mutations • Epigenetics • Lick rats • Homework

  36. Epigenome at a glance • http://learn.genetics.utah.edu/content/epigenetics/intro/

  37. Epigenetics • Modifications to DNA that do not change genes or DNA sequence. • These changes turn gene expression “on” or “off” • What does it mean to turn on a gene? • http://learn.genetics.utah.edu/content/epigenetics/control/

  38. Epigenetics Attaches to DNA- Blocks RNA polymerase from binding Turns genes “off” Loosens tightly coiled DNA. Allows access to DNA for transcription Turns genes “on”

  39. 11 Dec • Opener: • What makes one amino acid different from another? • Agenda: • Lick Rats • Protein Review • Plant cell drawing • Homework • 5.1 & 5.3 + GQs • Finish Plant Cell drawing

  40. Plant Cell Protein Synthesis Diagram Draw a picture of a plant cell going through the steps of transcription & translation . Make sure to include/label the following: • Nucleus • DNA • RNA polymerase • RNA nucleotides • pre-mRNA • Introns • Exons • Cap • Tail • Mature mRNA • tRNA • Ribosomes • Amino acids • Proteins • Include any other parts of the cell you know

  41. 12 Dec • Opener • How does your epigenome affect your DNA? • Agenda • Formative Quiz • Homework

  42. 13 Dec • Opener: Why were the two mice from the article so different? • Agenda • Review Quiz • Unit 5 Concept map • Study Guide • Homework • Study for Unit 5 Exam

  43. Unit 5 Concept Map • Make a concept map using the following terms from Unit 5: • DNA • Transcription • Translation • Mature mRNA • tRNA • pre-mRNA • Acetyl tag • Amino acid • Essential Amino Acid • introns • Non-essential Amino Acid • RNA polymerase • Nucleus • Methyl tag • Ribosome • Codon • Adenine • Thymine • Guanine • Uracil • Cytosine • Protein • exons • Mutations • Epigenetics • Cap and tail

  44. 14 Dec • Test Day

  45. EXTRA SLIDES

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