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Chapters 18 & 19 Bacteria Viruses & Operon Systems.

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Presentation on theme: "Chapters 18 & 19 Bacteria Viruses & Operon Systems."— Presentation transcript:

1 Chapters 18 & 19 Bacteria Viruses & Operon Systems

2 Key Topics for Ch. 18 & 19 Chapter 18 Topic Pgs. Bacteria:Genetic recombination Plasmids & Conjugation Transformation (Lab) Transposable elements Lac Operon System RegulatingGene Expression Viruses: DNA, RNA (retroviruses) Lytic & Lysogenic Cycle Chapter 19 Pgs. DNA & Chromatin packing into chromosomes Oncogenes & Tumor-supressor genes (Cancer) Transposons (B. McClintock) w/Indian corn375

3 Relative size Differences between of Viruses, Prokaryotes, and Eukaryotes

4 Bacterial Reproduction of DNA

5 Transformation Uptake of foreign DNA from the environment What we did in our lab (pGLO plasmid)

6 Conjugation and the transfer of the F Plasmid

7 Transduction

8 Detecting Genetic Recombination in Bacteria (pg. 347)

9 Intro. Q’s #5 for Chapter 20: Genetic Engineering 1)What does the acronym PCR stand for and what does this process do? 2)What does Gel electrophoresis allow us to do? 3)Give two applications of DNA profiling. 4)What are the advantages and disadvantages of genetic screening? 5)How is a cDNA library different from a genomic library? (p ) 6)Name two “vectors” that can be used for gene transfer. 7)Give two examples of a genetically modified crop or animal. 8)Briefly explain the process of gene therapy and give an example how it works. 9)Explain what a clone is and how it could be formed. 10)What are some of the ethical concerns about cloning? Give your opinion if you think cloning is something we should be doing.

10 Introductory Questions #6 1)How is Transduction different from conjugation? How is an “F plasmid” different from an “R plasmid”? 2)What are transposable elements and what do they do? What purpose do the insertion sequences play? 3)Name the two scientists that discovered the Lac operon system. What is the difference between an operator and a promoter? 4)How are repressible operons different from inducible operons? Give an example of each. 5)Name three example of a virus that has DNA as its genetic material and three examples of Viruses with RNA as its genetic material. 6)Briefly explain what a vaccine is and what it does. 7)From Ch. 19 (pg. 361) place these structures in correct order based on diameter size beginning with the smallest: -histone-chromatid-nucleosome-DNA 8)Name the organism that Barbara McClintock used to propose the idea of mobile genetic units (transposons). (pg. 375) 9)What is the difference between an oncogene and a tumor suppressor gene? Which one would the p53 gene qualify as? (pgs )

11 Insertion Sequences & Transposable Elements (pgs ) Always a part of of chromosomal or plasmid DNA Sometimes called “jumping genes”-never detach Inverted sequences are on each side of an insertion sequences. (See pg. 352) A single gene for coded for:transposase Specialized plasmids are constructed using these sequences.

12 Jacob & Monod Discovered Lac Operon – Nobel Prize for Discovering Control of Gene Expression

13 Regulation of a Metabolic Pathway

14 Specialized Genes Operator = "on/off" switch for operon Regulator = makes repressors to turn off an entire operon Repressor = Binds to operator, turn off gene expression Inducer = Joins with an active repressor, activates it Co-repressor = Joins with inactive repressor, converts it to active

15 OPERON THEORY Operon = group of structural genes regulated as a unit Several genes controlled by an operator site

16 Operon Complex RNA Polymerase must bind to the promoter site and continue past the operator site to transcribe mRNA

17 Repressible Operons (trp operon) Usually “ON” - to turn OFF: –Co-repressor needs to bind to an inactive repressor and activate it –RNA Polymerase then cannot bind and transcribe mRNA Ex. trp operon is a repressible operon: -trancription is usually on -inhibited only by tryptophan (corepressor)

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19 Trp Operon when Tryptophan is Absent

20 INDUCIBLE Operons (ex. lac operon) Usually “OFF” - to turn ON: –INDUCER needs to bind to an active repressor and inactivate it –RNA Polymerase can then bind and transcribe mRNA Ex. Lac operon is an inducible operon

21 Lac Operon Lactose ONLY used when glucose is not present in large quantities When glucose is present, cAMP levels are low, cAMP cannot bind to CAP and initiate enzyme production

22 Inactive Repressor-Lactose Present

23 Lac Operon In absence of glucose, cAMP levels are HIGH, binding to CAP can occur Beta-Galactosidase is made

24 Lac Operon RNA polymerase only binds efficiently when cAMP-CAP complex is in place Lac Operon = an INDUCIBLE Operon Lactose = an INDUCER –Binds to repressor and inactivates it

25 Lac Operon Summary

26 DNA & RNA Viruses

27 Lytic & Lysogenic Cycles of a Virus (Lysogenic:host is not destroyed)

28 5 Classes of Viruses-Pg. 340

29 Examples of Common Viruses DNARNA HerpesvirusEbola PoxvirusInfuenza Papovirus (warts)HIV Measels, Mumps Rabies West Nile

30 HIV Infection (pgs )

31 HIV infection on a White Blood Cell

32 Invasion of a Virus

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34 Key Concepts for Chapter 19 Review of DNA & Genome Oncogenes & Proto-Oncogenes Tumor Supressor Genes McClintok’s transposons

35 Chromatin Def: complex of DNA and proteins DNA Packing Histone proteins (+ charged amino acids w/ phosphates of DNA that are - charged) Nucleosome -”beads on a string”; basic unit of DNA packing Heterochromatin -highly condensed interphase DNA (can not be transcribed) Euchromatin -less compacted interphase DNA (can be transcribed)

36 The Biology of Cancer (review) Oncogenes & Tumor Suppressor Genes (RAS gene)(p53 gene)

37 Molecular Biology of Cancer pgs I. Proto-oncogene -----convert into Oncogenes -Controls cell growth(cell cycle & levels of cyclin) -Analogy: gas pedal is stuck in the down position ***Possible Causes: -movement of DNA &/or chromosome fragments -amplification; increases the number of copies of proto-oncogene -point mutation; protein product is altered II. Tumor-suppressor genes -Considered the “Guardian Angel gene” -Example (p53 gene) -Analogy: Break pedal is stuck in the up position

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39 Introductory Questions #6 1)How is Transduction different from conjugation? How is an “F plasmid” different from an “R plasmid”? 2)What are transposable elements and what do they do? What purpose do the insertion sequences play? 3)Name the two scientists that discovered the Lac operon system. What is the difference between an operator and a promoter? 4)How are repressible operons different from inducible operons? Give an example of each. 5)Name three example of a virus that has DNA as its genetic material and three examples of Viruses with RNA as its genetic material. 6)Briefly explain what a vaccine is and what it does. 7)From Ch. 19 (pg. 361) place these structures in correct order based on diameter size beginning with the smallest: -histone-chromatid-nucleosome-DNA 8)Name the organism that Barbara McClintock used to propose the idea of mobile genetic units (transposons). (pg. 375) 9)What is the difference between an oncogene and a tumor suppressor gene? Which one would the p53 gene qualify as? (pgs )

40 Assignt. Packet #3 (Ch ) Study Guide (finish chap. 19) Pre-Lab: Bacteria Transformation (pGlo lab) – pick up Pre-Lab: Analysis of Lamda DNA w/Gel Electrophoresis Videos x3: –DNA Blueprint of Life (3 segments) –Proteins (2 segments) –Using DNA Fingerprinting to solve crimes (2 cases shown) IQ’s x6 Cumulative Practice test (40 Quest.) – Printout results

41 Test #3 Breakdown (Ch ) Chapter 16: History/Discovery of DNA replication15 Chapter 17: Protein Synthesis (gene expression)18 Chapter 20: Recombinant DNA Technology14 Chapter 18: Gene regulation & Viruses 8 Chapter 19: Cancer Review/Transposons 2 Lab: 6 Cumulative Quest. (Ch. 1-19):12 ____________________________________________________ TOTAL Questions: 75 Topics to review: Proteins, Cell Respiration, Diffusion/osmosis # Questions


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