Chapter 11 Cell Communication Essentially the entire chapter with special focus on G protein coupled receptors Understand the basic reasons why cells of a multicellular organism need to communicate o In times of need cells signal to each other to produce a response for the stimulus from the environment Understand the basic method by which cells communicate long distance communication endocrine signaling o use hormones through the blood stream ex epinephrine fight or flight short distance communication paracrine signaling o local direct contact or secrete signaling molecules in a synapse synaptic signaling o closer to the original molecule stronger the signal o Receptor Ligand interactions Very specific GPCR g protein coupled receptor Transmembrane proteins Ligand signaling molecule sent out Hormone long distance Synaptic direct signal short distance o Changes in receptor shape in response to ligand binding Know the three major types of membrane associated receptors 1 GPCR 2 Receptor tyrosine kinsases a Similar to GPCR 3 Ion channel receptors a Normally closed off ligand receptor open the channel b No energy required o Focus on the G protein coupled receptors o What is the relationship between the receptor and the G protein G protein GTP binds to GPCR to receive the signal then transfers that signal to enzymes to begin the transduction o Distinguish between GDP and GTP bound G proteins and the nature of activation G proteins GTP active G proteins GDP inactive Active G proteins are able to take the signal from GPCR to enzymes who cannot receive the ligand on their own to start the transduction and response to the signal Know the one type of intracellular receptor o Non transmembrane receptors Ligand can enter cell on its own and react with receptors inside the cell Ex steroid hormones don t need anything to get into the cell they can do it o What types of signaling molecules are most likely to bind to intracellular receptors Understand the two major signal transduction mechanisms that we discussed through diffusion Steroid hormones o Phosphorylation cascades Addition of PO4 through protein kinases to activate proteins The cascade begins with one protein becoming activated which activates another and another Etc o Second Messengers Ex Mitogen Activated Protein MAP o Activated through the phosphorylation of MAP kinase MAP Kinase is only activated through phosphorylation of MAP Kinase Kinase etc NOT PROTEINS Know the three different second messengers that we discussed and how they are activated or produced 1 Cyclic AMP activated by adenylyl cyclase enzyme which converts ATP to cyclic AMP from an outside signal 2 Calcium ions activated as second messengers by changing the 3 concentration in the cytosol IP3 Inositol Triphosphate gprotein to phospholipase C to PIP2 to IP3 to endoplasmic reticulum to calcium ion channel Know the three major types of cellular response to signaling and the molecules and cellular machinery involved in each o Transcriptional nuclear response protein to nucleus transcription factor which will turn on off genes overall to stop or start the production of a specific gene transcription factor is the final molecule activated in the transduction sequence o Behavioral o Enzyme Activation All responses alter cell behavior Alters growth division of a cell what the cell produces etc Cytoplasmic response regulates enzymes by opening closing ion channels ex epinephrine impala vs cheetah epinephrine triggers glycogenolysis break down of glycogen into glucose to use in fight or flight response through a chain of enzyme activations Understand the mechanisms involved in differential cellular responses to signaling o How can a cell amplify a signal Enzyme cascades can increase the number of products given off by just one signal o How do two different cells respond differently to the same signal The same signal can affect two cells differently because each cell expresses a different combination of proteins that respond differently to the same signal o How can scaffolding proteins enhance the efficiency of a signal They physically bind proteins together creating a stronger signal than if each protein was on its own Know the basics of apoptosis CELL SUICIDE o What happens to a cell undergoing apoptosis A cell is chopped up its parts are packaged in vesicles and the vesicles are digested by outsider cells o The signal that triggers apoptosis can come from either inside or outside the cell The pathway that controls apoptosis in C elegans involves transduction steps that include negative regulation inhibition Ced 9 inhibits Ced 4 and Ced 3 which activated apoptosis When ligand and receptor interact it inhibits Ced 9 which activates Ced 4 and Ced 3 to trigger apoptosis Chapter 42 Circulation and Gas Exchange 42 1 42 2 the blood pressure section of 42 3 and general blood components in 42 4 Understand the need for a circulatory system in larger multicellular organisms There must be an exchange on a cellular level between the world and an Human beings for example our cells are buried too deep inside to interact with So a circulatory system brings nutrients cells need to them via blood hemolymph organism our surroundings in order to keep them alive o Gas and nutrient exchange is terribly slow beyond a few cell diameters Understand the example of the gastrovascular cavity as a simple example of gas exchange o Species without circulatory systems have a gastrovascular cavity that every cell is close to o The GC is able to diffuse nutrients into the cells as an exchange Acts as both digestive and circulatory system Be able to describe the difference between open and closed circulatory systems o Open no blood blood and interstitial fluid are mixed in hemolymph In insects athropods and mollusks o Closed separate fluids blood in vessels and interstitial fluid circulating the body Contain arteries veins and capillaries Artery AWAY from heart Vein TOWARDS heart Capillary exchange of gases nutrients occurs Be able to describe the difference between single and double closed circulatory systems o Single 2 chambered heart doesn t allow for high BP Blood passes through 2 capillary beds before returning to the heart Half of the blood is oxygenated the other half is not o Double 4 chambered heart oxygen rich and oxygen poor blood in the heart at the same time Know the unidirectional flow of blood through all four chambers of the human heart as well as important blood vessels of the pulmonary and
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