1nd Edition BIO 101 Lecture 19 Outline of Last Lecture II Cells III The cell cycle IV Mitotic phase V Asexual reproduction VI Telomeres VII Meiosis Outline of Current Lecture VIII Gene expression IX Inactivation of chromosomes X Translation XI Cell to cell communication XII Mutations XIII Cancer XIV Telomeres XV Epigenetics Current Lecture How to study Goal explain the relationships between terms These are concepts Binary Fission is a type of Asexual reproduction Study like you re studying for a short answer test DNA controls functions of the cell using RNA as employees Transcription Making RNA from DNA like training your employees Translation Making proteins from RNA If RNA only makes proteins how do other biological molecules get made o The proteins direct the synthesis of the other molecules These 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 Analogy DNA o Like superintendent of schools RNA o Like the school principals Proteins o Like the classroom teachers Carbs Lipids Nucleic Acid o Like the students Gene expression the production of proteins is regulated in several ways Gene regulation is the process of turning genes on and off Different cell types express different genes o For example not all cells need lactase In what cell types would you expect lactase gene expression o In the lining of the small intestine X chromosome inactivation is an extreme case of gene regulation In female mammals one X chromosome in each body cell is highly compacted and almost entirely inactive Gene Regulation is one wy to determine which proteins are produced by a cell There are several points along the path from DNA to protein that can be regulated Special transcription factors must bind to DNA to turn on transcription After Transcription the RNA may be altered in several ways gene regulation Before leaving the nucleus the RNA is modified o A cap and tail are added o Non coding introns may be removed o Protein coding exons may be rearranged Translation offers more opportunities for gene regulation The cell can control the following o Whether translation proceeds o How proteins are modified after translation o When proteins are broken down Cell to cell communication can control gene expression Multicellular life depends on cell to cell signaling Molecules exit one cell and bind to a receptor protein on the outside of another cell This binding triggers a signal transduction pathway 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 destroyed other cells Homeotic genes are master control genes they direct the location of the head and body parts Mutations in regulator genes can lead to an overgrowth of cells A mutated proto oncogene fails to regulate cell division and is called an oncogene Cancer is caused by the 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 The importance of Telomeres Telomeres allow replication of DNA without loss of genes Telomeres keep the ends of the chromosomes from sticking together or being damaged In young cells an enzyme called telomerase adds material to the ends of telomeres As cells divide may times there is not enough telomerase produced to add the telomeres Lack of telomerase Causes of Aging Telomere shortening o Chromosomes lose telomeres over time Chronological age o Risk factors increase over time Oxidative stress o Oxidants damage DNA proteins and lipids Glycation o Glucose sugar binds to and inhibits DNA proteins and lipids Telomerase and cancer Many cancers have shortened telomeres Measuring telomerase may be a way to detect cancer o They might be able to fight cancer by making cancer cells age and die There are risks Blocking telomerase could impair fertility wound healing and production of blood cells and immune system cells Epigenome We are a product of both our genes and our environment What are ways your physical or behavioral traits might be influenced by your genes your environment or both Importance of epigenetics The epigenome twists and untwists itself to make genes available for transcription The structure of the epigenome shapes the entire body Environmental factors determine how the epigenome is twisted Epigenetic tags attach for the life of a cell to continue to tell the cell what its function is These tags are copied during cell division Most epigenetic tags are erased in eggs and sperm but some escape the cleaning process Therefore you may be influenced by the experiences of your ancesto