BIO_SC 1010 1st Edition Lecture 11Outline of Last Lecture I. Genes are the units of inheritanceII. Humans are diploid organismsIII. How do you get one from two?IV. MeiosisV. Meiosis vs. MitosisVI. How unique are you?VII. How can Y chromosomes be used to trace paternity and ancestry?VIII. Errors in meiosisIX. Fetal chromosomal abnormalitiesX. Understanding of genetics XI. Meiosis can have mishapsOutline of Current Lecture I. Cell-to-Cell communicationII. MutationsIII. Gene Expression ControlIV. Cancer GeneticsV. How does your body protect itself from cancer?VI. Why is cancer so hard to stop?VII. Cancer TreatmentsVIII. Genetic EngineeringIX. Genetic ModificationX. The Human Genome Project was completed in 2003XI. Gene therapy aims to cure genetic diseasesCurrent LectureCell-to-Cell communication• Cell-to-Cell communication can control gene expression-multicellular life depends on cell-to-cell signaling-molecules exit one cell and binds to a receptor protein on the outside of another cell-this binding triggers a signal transduction pathwayThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• A signal from another cell can regulate genes (turn on or off) in the receiving cell• Cell-to-cell communication is particularly important in a developing embryo-development involves frequent cell division (to increase body size) that must be carefully coordinated -inductive signals can cause cells to change shape, migrate, or even destroy other cells -homeotic genes are master control genes; they direct the location of the head and body parts Mutations• A mutation is any change in the nucleotide sequence of DNA-replacing-deleting-adding-mutations are the raw material of evolution by natural selection-however, mutations can be harmful• Mutations in DNA can change the protein produced-mutations can be: spontaneous or induced by mutagens (high energy radiation, chemicals)• Point mutations occur at a single nucleotide • Frameshift mutations are due to the addition or deletion of a nucleotide-often results in different or defective proteins Gene Expression Control• Loss of gene expression control can result in cancer-mutations can lead to a mass of body cells growing out of control, a tumor-if a tumor spreads to other tissues, the person is said to have caner • Genes regulate the cell cycle-a cell cycle control system regulates the timing of cell duplication-a proto-oncogene codes for proteins that tell the cell when to duplicate• Mutations in regulator genes can lead to an overgrowth of cells-a mutated proto-oncogene fails to regulate cell division and is called oncogene*cancer is caused by out-of-control cell growth due to a breakdown of the cell cycle control system• Cancer can occur when proto-oncogenes are mutated to oncogenes -a mutation in a growth factor gene can produce a hyperactive protein that promotes unnecessary cell division-a mutation that deactivates a tumor suppressor gene may result in uncontrolled growth *mutations may result in proteins that either don’t stop the cell cycle or stimulate growth Cancer Genetics• It usually takes more than a single mutation in a cell to cause cancer. In most cases, a cellwill become cancerous only after it has acquired mutations in several genes that regulate the cell cycle or repair DNA • As cells accumulate mutations over time through exposure to carcinogens and repeated rounds of cell division, the chances increase that a cell will accumulate enough mutations to become cancerous • People who have inherited high-risk mutations start life with at least one cancer-predisposing mutation, so they need fewer additional mutations to get cancer How does your body protect itself from cancer?• DNA repair molecules -but some mistakes are missed• The immune system destroys abnormal cells-but cancer cells are still ‘self,’ and are therefore often ignored by the immune system• Limited cell life-span• ‘Counters’ are chopped off chromosomes each time cell divides – keeping track of how many divisions have occurred • Most cells are limited to 100-150 division-prevents accumulation of mutation-but sometimes the ‘tail-chopping’ mechanism fails (cancer cells often add the counters back on)Why is cancer so hard to stop?• Cancer cells are part of the body (unlike other diseases)• Methods for killing cancer cells also kill other cells of the body • Cancer is caused by out-of-control cell growth -cancer begins within a single cell when proto-oncogenes mutate into oncogenes • A tumor is an abnormally growing mass of body cells-the spread of cancer cells in the body is called metastasis -benign tumor (no spreading)-malignant tumor (spreading)• There are ways to reduce cancer risk-healthy diet-exercise-regular screenings-not smoking-sun protectionCancer Treatments• Surgical removal• Radiation – destroys the DNA in cancer cells • Chemotherapy – poisons the cancer -affects all cells undergoing cell division • Other/Future therapies1. Use immune cells to deliver toxic drugs directly to the cancer-allows the use of more toxic drugs 2. Use drugs to interfere with a tumor’s blood supply 3. Use vaccines to alert the immune system to cancer4. Cause cancer cells to mature and differentiate -slow cell division5. Prevent ‘counters’ from being reattached 6. Block hormone receptors -receptor sends a message to the nucleus 7. Block activator proteins produced by oncogenes -tailors treatment to individual patient’s mutations Genetic Engineering • Genetic engineering involves manipulating DNA for practical purposes -biotechnology is the manipulation of organisms or their components to make useful products -DNA technology is a set of methods for studying and manipulating genetic material-genetic engineering is the direct manipulation of genes for practical purposes • Gene cloning is an example of genetic engineering -we can insert DNA into bacteria and have them do the work• Cutting and pasting DNA is an important step in genetic engineering -restriction enzymes are proteins that cut DNA at specific nucleotide sequences-the resulting fragments are called restriction fragments Genetic Modification• Plants and animals can be genetically modified -genetically modified organisms (GMOs) are ones that have acquired one or more genes by artificial means • GM plant crops currently make up a