Chapter 5 Learning Objectives

Transcription

1 Schedule and Announcements Go over Exam 1 Look at Elodea (plant cells) Start Chapter 5 Quiz Thursday over lab material Science Café 2 Friday Don t forget- research plan for project is due Friday September 25 Chapter 5 Learning Objectives Describe what DNA is and what it does. Explain the process of gene expression and the collaboration of nature and nurture. Explain the causes and effects of damage to the genetic code. Discuss biotechnology in agriculture. Describe biotechnology and its implications for human health. DNA: what is it, and what does it do? DNA Double Helix Sugars, Phosphates, and Bases A, T, C, and G base pairs Nucleic acids and nucleotides 1

2 The number of chromosomes varies from species to species. Genes Corn has 10 unique chromosomes. Fruit flies have only four. Dogs and chickens have 39 different chromosomes. A sequence of bases in a DNA molecule that carries the information necessary for producing a functional product, usually a protein molecule or RNA Goldfish have 47 chromosomes. Individuals in each of these species inherit one copy of each chromosome from each parent. An onion has five times as much DNA as a human. Why doesn t that make them more complex than us? 2

3 The Proportion of the DNA That Codes for Genes Introns Non-coding regions of DNA May take the form of short (or long) sequences that are repeated thousands of times May also consist of gene fragments, duplicate versions of genes, and pseudogenes Genotype All of the genes contained in an organism Phenotype The physical manifestations of the instructions 5.6 Transcription: Reading the information coded in DNA 3

4 Several ingredients must be present in the cytoplasm for translation to occur: Free amino acids Ribosomal units Transfer RNA The Genetic Code Insert figure 5-14 Microarrays A powerful tool used to monitor the expression levels of thousands of genes simultaneously Insert figure 5-15 Particularly useful in exploring how gene expression differs in response to an illness, or the treatment of an illness, or in response to aging 4

5 Controlling Gene Expression Transcription factors Proteins that bind to specific regulatory sites on the DNA Prokaryotic Gene Control and the lac Operon Positive control Insert figure 5-17 Negative control Elements of Gene Control Promoter Operator Regulatory gene Eukaryotic Gene Control There are many other ways that genes can be regulated besides operons. Transcription Regulation Activators and repressors Enhancer sequences Chemical interference What causes a mutation, and what are its effects? Alteration of the sequence of bases in DNA can lead to changes in the structure and function of the proteins produced. have a range of effects. Post-Transcription Regulation 5

6 Breast Cancer in Humans There are two human genes, called BRCA1 and BRCA2. More than 200 different changes in the DNA sequences of these genes have been detected. Each of these changes results in an increased risk of developing breast cancer. Mutations in Sex Cells and Non-Sex Cells Differences? Which may get passed on to offspring? A fast-flush response Insert figure 5-23a Insert figure 5-23b From mutation to illness in just four steps: 1. A mutated gene codes for a nonfunctioning protein, usually an enzyme. 2. The non-functioning enzyme can t catalyze the reaction as it normally would, bringing it to a halt. 6

7 From mutation to illness in just four steps: 3. The molecule with which the enzyme would have reacted accumulates, like a blocked assembly line. 4. The accumulating chemical causes sickness and/or death What is biotechnology? Genetic engineering Adding, deleting, or transplanting genes from one organism to another, to alter the organisms in useful ways Insert figure 5-24 Insert figure 5-25 Insert figure 5-26 Insert figure

8 Insert figure 5-28 Insert figure Biotechnology can improve food nutrition and make farming more efficient and eco-friendly. Insert figure 5-30 How might a genetically modified plant help 500 million malnourished people? Nutrient-rich golden rice Almost everyone in the United States consumes genetically modified foods regularly without knowing it. What foods are responsible for this? 8

9 Insect Resistance How can genetically modified plants lead to reduced pesticide use by farmers? Insert figure 5-33 Herbicide Resistance Faster Growth and Bigger Bodies 5.13 Fears and risks: Are genetically modified foods safe? 9

10 Fear #1. Organisms that we want to kill may become invincible. Fear #2. Organisms that we don t want to kill may be killed inadvertently. Fear #3. Genetically modified crops are not tested or regulated adequately. Fear #4. Eating genetically modified foods is dangerous. Fear #5. Loss of genetic diversity among crop plants is risky. Fear #6. Hidden costs may reduce the financial advantages of genetically modified crops. The treatment of diseases and production of medicines are improved with biotechnology. Biotechnology has the potential for improving human health (and criminal justice) Preventing diseases Curing diseases Treating diseases The treatment of diabetes Insert figure 5-39 Why do some bacteria produce human insulin? Recombinant DNA technology 10

11 Several important achievements followed the development of insulin-producing bacteria, including: 1. Human growth hormone (HGH) 2. Erythropoietin What is blood doping? How does it improve some athletes performance? Medical Applications Gene therapy Adding a functional copy of a gene to correct a hereditary disorder Ex Vivo (outside the body) SCID patients In Vivo (inside the body) cystic fibrosis Severe combined immunodeficiency disease (SCID) illustrates both the potential and the problems Children lack the enzyme ADA (adenosine deaminase) Involved in the development of T and B cells Bone marrow stem cells Successful at first, but then patients developed a rare leukemia 64 Medical Applications-Vaccines DNA Analysis-Forensic Applications

12 DNA Analysis-Forensic Applications DNA fingerprinting An identification technique used to detect differences in the DNA of individuals Makes use of a variety of molecular procedures, including RFLP analysis First used in a US criminal trial the late 1980s Tommie Lee Andrews was found guilty of rape What is a DNA fingerprint? 67 Insert figure