Slide 1 / 155 Slide 2 / 155 New Jersey Center for Teaching and Learning AP BIOLOGY Progressive Science Initiative GENES This material is made freely available at www.njctl.org and is intended for the non-commercial use of students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning September 2011 community, and/or provide access to course Henriquez, Lageman, Satterfield materials to parents, students and others. www.njctl.org Click to go to website: www.njctl.org Slide 3 / 155 Slide 4 / 155 Genes Unit Topics Discovery of DNA Click on the topic to go to that section · Discovery of DNA · DNA Structure & Semi-Conservative Replication · DNA Replication · RNA Transcription · Gene Expression, Central Dogma · Three Types of RNA, Translation · Article Discussion Day Return to Table of Contents Slide 5 / 155 Slide 6 / 155 Deoxyribonucleic Acid DNA Recall that a DNA is a molecule that stores and To understand the "secret of life" scientists had to figure out transmits genetic information. the chemical and physical nature of the gene - the factor passed from parent to offspring that directs the activity of the cell and determines traits. By applying basic principles of physics and chemistry and keeping up on the latest discoveries of their time, a group of remarkable scientists were able to determine the structure of DNA.
Slide 7 / 155 Slide 8 / 155 DNA and Modern Medicine "Standing on the Shoulders of Giants" The proof that DNA is the carrier of genetic information involved The discovery of the structure and function of DNA has led to a number of important historical experiments. These include: astounding leaps in understanding of biology, heredity, and modern medicine. Griffith Transformation Experiment "It's impossible to overstate the importance of knowing the Avery-Macleod-McCarty Experiment structure of DNA." - Francis Collins, Director of the Human Genome Project Hershy-Chase Experiment Contributions of Watson, Crick, Wilkins, and Franklin Click Here to see a DNA timeline Slide 9 / 155 Slide 10 / 155 Griffith's Colonies Griffith and Transformation One strain grew in rough colonies and did not cause disease. The other strain grew in smooth colonies and caused disease. In 1928 British Scientist Frederick Griffith was conducting experiments with mice to determine how bacteria made people sick. Caused Griffith isolated two different strains of pneumonia bacteria disease from mice and grew the bacteria on petri dishes in the lab. Did not cause disease R strain S strain colonies colonies Slide 11 / 155 Slide 12 / 155 Mouse Mortality Mice and the 2 strains When he injected the mice with the rough (R) strain, they lived. When he injected the mice with the smooth (S) strain, they died. Heating the S strain However, when he heated the S strain of bacteria, killing killed the them, and then injected the heat-killed S strain bacteria into the bacteria and mice, they did not die. prevented them from passing disease to the mice.
Slide 13 / 155 Slide 14 / 155 Griffith: Part 2 Griffith Experiment Part 2 Griffith then mixed heat-killed disease-causing S strain bacteria with live, harmless R strain bacteria and injected this mixture into mice. Before neither heat-killed S strain or live R strain bacteria made the mice sick, but the mixture of the two caused the mice to develop pneumonia and die. Slide 15 / 155 Slide 16 / 155 What was the chemical factor? What was in the mice lungs? Griffith examined the lungs of mice that had been infected with the mixture of dead S strain and live R strain bacteria He also noted and found them filled with disease-causing bacteria. this factor was passed This indicated that a chemical factor was transferred from the on as the dead S strain bacteria to the live R strain bacteria that bacteria transformed them into disease-causing bacteria. reproduced. Slide 17 / 155 Slide 18 / 155 1 What is bacterial transformation? 2 Why was Griffith's experiment significant? The inheritance of genetic material A It showed that a chemical factor transformed A R strain bacteria into S strain bacteria The exchange of genetic material between B strains of bacteria It proved dead bacteria could still transmit B disease directly to mice The interaction between strains of bacteria C It indicated proteins were the source of The passage of genetic material from parent C D genetic material to offpsring None of the above D
Slide 19 / 155 Slide 20 / 155 Avery's Experiment Avery, Macleod, MacCarty First they repeated Griffith's experiment by mixing heat-killed S Oswald Avery, Colin MacLeod, and Maclyn McCarty were the strain and R strain bacteria and verifying transformation first to demonstrate that DNA was the substance that caused occurred.Then they lysed the S cells by adding detergent. bacterial transformation. Avery's group built on Griffith's work Detergent disrupts the cell membrane and cell wall, causing the to determine which chemical was responsible for transforming DNA, RNA, proteins and other molecules to spill out. the R strain bacteria. They mixed the S lysate In the 1930s and 1940s, at the with R strain bacteria and Rockefeller Institute for Medical determined that the Research in New York City, Avery contents of cell parts in the Lysate and his colleagues suggested that S lysate still allowed DNA, rather than protein as was transformation to occur. believed at the time, was the hereditary material in bacteria. Slide 21 / 155 Slide 22 / 155 Their Three Mixtures 3 What does the enzyme RNase do? Next they mixed heat-killed S strain lysis containing DNA, Breaks down RNA molecules A RNA, and Protein with R strain bacteria and allocated the mixture into three test tubes: Synthesizes RNA molecules B Breaks down proteins C To tube A they added DNase - an enzyme that destroys DNA molecules. Synthesizes proteins D To tube B they added RNase. To tube C they added Protease. Finally, they injected each mixture into the mice and waited for results. Slide 23 / 155 Slide 24 / 155 Avery's Results 4 If DNA were the molecule being transferred from dead S strain bacteria to live R strain bacteria, then the mice injected with DNase treated bacteria would most likely The results of the experiment showed that the mice injected with Survive A both the RNase and Protease treated bacterial cells died. Die B However, the mice injected with Remain unaffected C the DNase treated bacterial cells survived. Pass on pneumonia to their offspring D *Destroying the DNA prevented transformation of R strain bacteria.
Slide 25 / 155 Slide 26 / 155 Hershey and Chase 5 What did Avery's experiment prove? Bacteria can exchange genetic information Alfred Hershey and Martha Chase conducted a series of A experiments helping to confirm that DNA was the genetic material in cells. DNA is the molecule that causes bacterial B transformation Hershey and Chase showed that RNA and Proteins are the molecules responsible for when viruses (made of proteins C and DNA) infect bacteria, their transferring genetic information DNA enters the host cell but most DNase breaks down DNA molecules D of their proteins do not. Hershey shared the 1969 Nobel Prize in Physiology for his work involving the genetic nature of viruses. Slide 27 / 155 Slide 28 / 155 The Hershey Chase Experment 6 What would you expect to see if protein had been injected into the cell instead? Red-labeled cells A Green-labeled cells B Cells containing phosphorous C Cells containing oxygen D Slide 29 / 155 Slide 30 / 155 DNA Structure & Semi- Structure of DNA Conservative Replication In 1962, the Nobel Prize in Physiology and Medicine was awarded to James Watson, Francis Crick, and Maurice Wilkins for their determination of the structure of DNA in 1953. Unfortunately, the rules of the prize award state it can only go to the living. This meant Wilkin's colleague Rosalind Franklin who collected all the data they used could not receive honor. Franklin died at the age of 37 in 1958 from ovarian cancer which is thought to be the result of her work with X-ray Return to radiation incurred while doing the Table of research. Contents
Recommend
More recommend
