1 / 60

Chapter 8 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into

Chapter 8 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Homework. Chapter 7. Chapter 8. P 151 Do the 3 Questions under intro on sickle cell anemia Concept Review #1, 2, 3,4,5,6,7,9,11. Concept Review

ceana
Download Presentation

Chapter 8 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 8 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.

  2. Homework Chapter 7 Chapter 8 P 151 Do the 3 Questions under intro on sickle cell anemia Concept Review #1, 2, 3,4,5,6,7,9,11 • Concept Review • #1, 2, 3, 6, 8 Draw diagram that illustrates how photosynthesis and respiration are related

  3. What are some reasons we should learn about DNA?

  4. Review • What is transcription? • What is translation? • What are the DNA bases? • What are the RNA bases? • How do they pair up?

  5. What were some of the organisms that you learned about in the first lab exercise yesterday? • What is a mutation? • What is a gene?

  6. DNA and the Importance of Proteins • The recipes for proteins are found in the cell’s DNA. • DNA is organized into genes. • Each gene is a recipe for different proteins.

  7. Nucleic Acid Structure and Function • DNA accomplishes two things: • Passes genetic information to the next generation • Controls the synthesis of proteins • DNA is able to accomplish these things because of its unique structure. • So, how do we know DNA’s structure?

  8. Important Researchers in the Search for DNA’s structure • Frederick Griffith, Linus Pauling, Chargaff, Oswald Avery and associates, Alfred Hershey and Martha Chase

  9. James Watson and Francis Crick

  10. The race to determine the structure of DNA X-ray diffraction image of DNA taken by Rosalind Franklin in 1951 Maurice Wilkins Rosalind Franklin Photo 51 Wet DNA

  11. Nobel Prize 1962: Watson, Crick, Wilkins What about Rosalind Franklin?

  12. DNA Structure • DNA is a nucleic acid. • Nucleic acids • Large polymers made of nucleotides • A sugar molecule • Deoxyribose for DNA • A phosphate group • A nitrogenous base • Adenine • Guanine • Cytosine • Thymine

  13. What is the difference between purines and pyrimidines?

  14. DNA Structure • DNA is double- stranded. • Held together by hydrogen bonds between the bases • A-T, G-C • Why do you think they pair this way?

  15. Base Pairing Aids DNA Replication • DNA replication • Why does the cell need to replicate its DNA? • Is the process by which DNA is copied • This is done before cell division. • Provides the new cells with a copy of the genetic information • Relies on the base-pairing rules

  16. Base Pairing Aids DNA Replication • Is accomplished by DNA polymerase and other enzymes • DNA Helicase binds to DNA and forms a replication bubble (or replication fork) by separating the two strands. • DNA polymerase builds new DNA strands that will pair with each old DNA strand. • Where there is an A on the old strand, polymerase will add a T to the new strand. • When DNA polymerase finishes a segment of new DNA, it checks its work and corrects mistakes if they happen.

  17. DNA Replication Helicase: unzips DNA Polymerase: incorporates nucleotides into new strand

  18. DNA replication • http://www.youtube.com/watch?v=zdDkiRw1PdU&feature=related

  19. Handout on DNA Replication • Complete the handout and questions; you may work together

  20. Repairing Genetic Information • If a mistake is made when building the new strand • The old strand still has the correct information. • This information can be used to correct the new strand.

  21. The DNA Code • The order of bases in the DNA molecules is the genetic information that codes for proteins. • The sequence of nucleotides forms words that are like a recipe for proteins. • Each word contains three base letters. • (base triplet) • ATGC are the four letters that are used to make the words. • Each three-letter word codes for a specific amino acid. • The order of amino acids in the protein is determined by the order of nucleotides in DNA.

  22. RNA Structure and Function • RNA vs. DNA • RNA has ribose sugar (DNA has deoxyribose). • RNA contains the bases • Adenine • Guanine • Cytosine • Uracil (DNA has thymine)

  23. DNA vs. RNA • RNA’s, like DNA’s, base sequence carries information. • RNA is made in the nucleus and transported to the cytoplasm (DNA stays in the nucleus). • The protein coding information in RNA comes from DNA. • Like DNA replication, RNA synthesis follows the base-pairing rules (A-U; G-C). • RNA is typically single-stranded (DNA is typically double-stranded). • Three types of RNA participate in protein synthesis • mRNA • tRNA • rRNA

  24. What are differences in DNA and RNA?

  25. Protein Synthesis • The sequence of nucleotides in a gene dictates the order of amino acids in a protein. • Before a protein can be made • The information in DNA must be copied into RNA. • This process is called transcription. • The information in the RNA can then be used to make the protein. • This process is called translation.

  26. Transcription animation • http://www.youtube.com/watch?v=ztPkv7wc3yU

  27. Transcription • During transcription • DNA is used as a template to make RNA • Accomplished by RNA polymerase and follows the base-pairing rules • The process of transcription • Occurs in the nucleus • RNA polymerase separates the two strands of DNA. • Only one of the two strands will be used to create the RNA. • The coding strand • The other DNA strand is called the non-coding strand.

  28. Transcription of an RNA Molecule

  29. The Process of Transcription • Only a segment of the DNA strand will be used to create each RNA. • These segments are called genes. • Each gene starts with a promoter. • The RNA polymerase binds to the promoter to start building an RNA strand. • Each gene ends with a terminator sequence. • The RNA polymerase will stop transcribing at the terminator sequence.

  30. Translation animations • http://www.youtube.com/watch?v=B6O6uRb1D38&feature=related • http://www.youtube.com/watch?v=5bLEDd-PSTQ&feature=related

  31. Translation • Three types of RNA participate in translation. • mRNA carries the recipe for making the protein. • tRNA and rRNA are used to read the recipe and build the amino acid chain. • Codons are sets of three nucleotides on mRNA that code for specific amino acids. • tRNA reads the codons and brings the correct amino acids.

  32. Translation

  33. The Genetic Code

  34. Translation • Ribosomes are organelles that build proteins. • rRNA is found in ribosomes. • mRNA is read on ribosomes. • Ribosomes are found in two places in the cell. • Free-floating in the cytoplasm • Bound to the endoplasmic reticulum

  35. Translation Initiation • Translation begins when • The small ribosomal subunit binds to the beginning of the mRNA and searches for the AUG start codon. • At this point, a tRNA brings the first amino acid. • The anticodon in the tRNA matches with a codon on the mRNA. • Each tRNA carries a specific amino acid based on its anticodon. • The start codon, AUG, binds to a tRNA that carries a methionine. • Finally, the large ribosomal subunit joins the complex and the next step, translation elongation, can proceed.

  36. Initiation

  37. Translation Elongation • The next tRNA binds with the next codon on the mRNA. • The ribosome adds this amino acid to the growing polypeptide. • The ribosome then moves down to the next codon. • The process repeats itself. For each step, a new amino acid is added to the growing protein.

  38. Elongation

  39. Translation Termination • Elongation continues until the ribosome encounters a stop codon. • UAA, UAG, UGA are stop codons. • A release factor binds to the stop codon. • This causes the ribosome to release the polypeptide. • The ribosomal subunits separate and release the mRNA. • The mRNA can be translated again by another ribosome.

  40. Termination

  41. Relationship of DNA Base Sequence to Peptide Structure

  42. Summary of Protein Synthesis

  43. The Genetic Code is Nearly Universal • The process of making proteins from the information in DNA is used by nearly all cells. • Nearly all organisms studied to date use the same genetic code. • Because of this, we are able to use bacteria as factories to make massive amounts of proteins. • Insulin, growth factor, etc.

  44. Control of Protein Synthesis • Gene expression is how the cell makes a protein from the information in a gene. • Cell types are different from one another because they express different sets of genes. • Therefore, have different sets of proteins • Cells control gene expression in response to different environmental conditions. • Cells can alter gene expression • Controls the quantity of a protein • Controls the amino acid sequence of a protein

  45. Control of Protein Quantity • Cells can regulate how much of a given protein is made by • Controlling how much mRNA is available for translation • Cells do this in a number of ways: • Regulating how tightly the chromatin is coiled in a certain region • The more tightly the chromatin is coiled, the less likely a gene in that region will be transcribed.

  46. Eukaryotic Genome Packaging

  47. Control of Protein Quantity • By increasing or decreasing the rate of transcription of the gene by enhancer and silencer regions on the DNA • Activation of enhancer regions increases transcription. • Activation of silencer regions decreases transcription. • Through the binding of transcription factors, • These proteins bind to the promoter and facilitate RNA polymerase binding and transcription. • By limiting the amount of time the mRNA exists in the cytoplasm, • Some mRNA molecules are more stable and will exist longer in the cytoplasm, yielding more protein.

  48. Different Proteins from One Gene • Eukaryotic cells can use one gene to make more than one protein. • In eukaryotic genes, non-coding sequences called introns, are scattered throughout the sequence. • After transcription, the introns must be cut out and the coding regions, called exons, must be put back together. • This is called splicing.

  49. Transcription of mRNA in Eukaryotic Cells

  50. Alternative Splicing • Different combinations of exons from a single gene can be joined to build a number of different mRNAs for a number of different proteins.

More Related