Orbital Overlap; Hybrid Orbitals (Sections)Indicate the

Week 3 - Chapter 15 - KNOW ORGANELLS AND FUNCTION - 54% cytosol, 22% mitochondria, 12% ER, 6% nucleus, 3% Golgi apparatus - All organelles are surrounded by a lipid bilayer like the plasma membrane - The address in the protein is always an amino acid which tells the protein where to go o Proteins enter the nucleus through nuclear pores o Nucleus is very rigid/stiff cytoskeleton o Go through a meshwork of filaments to get into the nucleus o NLS sequence- “take me to the nucleus” o Nuclear importer will bind to the protein with the NLS, and it will dumb its cargo into the nucleus o Ran-GTP (when importer and nuclear protein comes into the nucleus) causes the importer to dump its cargo  When importer makes it to the cytosol, the Ran-GTP is hydrolyzed, Ran-GDP is then fallen off o NF-AT (T-cells) normally in the cytosol, phosphorylated, the nuclear sequence is hidden, sits in cytosol, when phosphate groups are taken off (calcineurin-phosphatase (when calcium is there)),  when calcium levels are low (nucleus) calcineurin falls off and NF-AT is taken out of the nucleus - proteins unfold to enter mitochondria and chloroplasts o membrane is more fluid o transport proteins in the membrane o two lipid bilayers  some proteins need to be in lumen, matrix, inner membrane, or outer membrane o cytosol to matrix  TOM (transporter of outer mitochondrial membrane),  TIM (inner) Multi-pass proteins  When the protein arrives to the transport protein, the protein has to be stretched out in a long peptide strand (chaperone protein help the protein to not fold back (Hsp70)) ATP (NEEDED) causes the removal of Hsp70  Once protein is in the matrix, peptidase will cleave the signal sequence off the protein - Peroxisomes o Proteins enter peroxisomes from both the ER or cytosol o Peroxisomes are detoxifiers o Form myelin when myelin is wrapped around the axon, the proteins are pushed to the side  Na+ cannot get out until it passes the myelin chief (Na+ jumps and causes the action potential to go faster)  Phospholipid is made in the peroxisome which makes myelin  Zellweger Syndrome (mutates in the Pex2 gene)’ Week 2, Lecture 2 - Cathrin has adapter protein (adaptin) recognizes cargo proteins o Phosphatidylinositol’s reacts with dynamin and sequences, you end up with vesicle dynamin falls offadaptin falls off vesicle  Dynamin requires energy in the form of  Mutation in dynamin loses functioning in peripheral nerve neurotransmitter release (Charcot-Marie-Tooth) destroys neurotransmitters to make muscles contract - Vesicles has to dock in order to embed proteins in the plasma membrane o RAB vesicle docking  Interact with vesicle by phosphatidylinositol’s  Tethering protein recognizes RAB and brings it close to the target membrane  Requires Ca2+ to come in the  SNARE proteins (in vesicle and membrane) SNAREs interact  In the presence of Ca2+, they twist together and pull membrane pieces of vesicles and target membrane together  Inner leaflet of target membrane and outer leaflet of vesicle bind together after SNAREs start twisting then you end up with inter leaflet of vesicles forming into the outer leaflet of target membrane  Synaptotagmin is the Ca2+ sensor  interacts with vesicle SNARE and allows the SNAREs to interact (ESSENTIAL FOR VESICLE TO FUSE TO MEMBRANE)  SNARE proteins are targets for toxins (tetanus, Botox, etc.) o RAN in the nucleus Week 2, lecture 3 - Calcium, action potential, voltage-gated channel, and sodium potassium pumps is required for neurotransmitter release - Which is not needed for vesicles fusion: RAB - Proteins embedded in the membrane usually have - Carbohydrates are added in the lumen of the ER and the lumen of the Golgi - Lipids link to proteins in the ER and the Golgi where sugars are added (glycolipids) o GPI-linked proteins (glycolphosphatidylinosital) o We almost never find GPI-linked proteins in the cytosol side of the cell membrane or the outside of the Golgi/ER membrane - Chaperone proteins (BIP/HSP70) bind to proteins to help them fold properly o Proteins that fold incorrectly mutations in the chaperone proteins o Proteins aggregate together and they clog up cells o ER and cytosol - If they fold incorrectly the cell ramps up production of new proteins - TOW protein aggregate together, microtubules fall apart, then the proteins aggregate together, and neuron doesn’t work  Alzheimer’s o Cell then turns up transcription and translation of the TOW proteins ER gets bigger - Sensory mechanisms when the signals detect a change in the folding, there is a signal that goes into the cytosol (heat shock proteins are an example of this) - What happens in the Golgi modification starts at the cis part is closest to the ER and goes to the trans side - Targets: o Plasma membrane secrete o Secretory pathways  Constitutive pathway just dumping things out  Regulated secretion pathway is signaled - Endocytic pathways: o Phagocytosis--. Macrophage destroys bacterium (surrounds its membrane around) brings to (driven by receptor by signals in the macrophage reorganizes the cytoskeleton and pushes its own membrane around) o Pinocytosis bring in fluid and small molecules outside of the cell  Primary mechanism to recycle the membrane o Receptor-driven endocytosis  Cholesterol in the cell cholesterol is packaged in LDL binds to LDL receptorsrecruits clathrin in the cell membrane forms vesicle with receptor and LDL in them  Recycling pathway vesicles fuse and form large endosome PH drops and LDL with receptor breaks free and then be able to signal again at the plasma membrane o What do you do with everything inside the vesicle  Recycle back out (LDL receptor/aquaporin’s)  Bring it to lysosome and degrade it  Trans-cytosis: happens in the gut  IgA has an important function in the lumen but made on the underside of the epithelial tissue of the gut  IgA binds to receptor membrane buds off vesicles have receptor (IgA molecule in them) fuse on the top membrane in the gut goes out and antibody is not in the lumen o Lysosome: all acidic enzymes in the lysosome  You put an ATP-driven pump on the lysosome and brings H+ inside the cell 