CHEM 332 1st Edition Lecture 1 What is science Three levels o The best science is asking new questions and seeking answers Gene Expression vs Transcription For a gene to be expressed it MUST be a functional protein and has to be doing something o For it to be function it must be turned on o Gene expression is the process going from DNA a functional protein Every step in that process from beginning to end can be regulated Regulation biological decision making Every step in a biological process is a potential site of regulation Typically regulation happens early on transcription saves the most energy The quickest response is to regulate at the last step protein activity control o Only turning on of Organs and Tissues Roughly 210 cell types in human About 100 trillion total cells in an adult human Only one cell needs to become cancerous for someone to get cancer o Cancer is rare on a per cell basis Cells within a tissue o Not in the tissue alone many cells around them o Tissue made of diferent types of cells that need to work together o Tissues stay the same size and shape and have relatively the same function throughout your whole life Cells are dying continuously must be a way to replenish cells that balances with the amount of cell death This way organ has the same number of cells and keeps the same size shape Tissue Homeostasis Series of events for the tissue to be maintained throughout life o Job of stem cells Stem Cells Stem cells divide only when you need cells to be replenished and develop into the cells that have died Terminal Differentiated cells are stem cells that are developed and specialized don t divide 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 o o When they die they need to be replenished by stem cells Stem cells are self renewing when a stem cell divides it gives rise to a new stem cell so you don t run out of them and the other cell can go on to divide and diferentiate into whatever the body needs it to be o This process takes several steps Symmetric division Divide to give rise to two identical cells Asymmetric division Divide to give rise to two diferent cells Adult stem cell give rise to diferent cell types BUT only to a specific subset of diferentiated cells o Multipotent Embryonic stem cell give rise to ALL cell types o Pluripotent Signaling Pathways Cells talk to each other all the time Signal Transduction one cell sends out a signal that s received by another cell The receiving of a signal triggers a series of events involves multiple steps o ex A cell will receive a signal and it might turn on a protein which will turn on another protein o Received at the cell surface and efecting events that occur in the cell nucleus or cytoplasm and the signal molecule never goes into the cell Signaling molecules ligands proteins peptides amino acids nucleotides steroids fatty acid derivatives and gases Signaling proteins that are sending the signal into the cell are usually kinases not always Sometimes the signaling molecule goes into the cell hydrophobic proteins Hydrophobic proteins can get through the cell membrane o Nuclear hormone receptor can bind the hydrophobic protein in the membrane and then go straight to the nucleus