Week 5 LS2 notes
Week 5 LS2 notes Life Sciences 2
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This 6 page Class Notes was uploaded by Jenna Kovsky on Friday October 30, 2015. The Class Notes belongs to Life Sciences 2 at University of California - Los Angeles taught by Dr. Cooper/Dr. Esdin in Fall 2015. Since its upload, it has received 17 views. For similar materials see Cells, Tissues, and Organs in Biology at University of California - Los Angeles.
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Date Created: 10/30/15
102615 Lecture 13 Cell Comm lcont and Photosvnthes o apoptosis green falling leaves muscarinic AChR cGMP lowers Ca2 which leads to smooth muscle relaxation cAMPgtphosphodiesterase turns it into 5 AMP CGMPgt5 GMP using a phosphodiesterase 0 viagra inhibits this phosphodiesterase o corpus cavernosum fills with blood keeping the penis erect PHOTOSYNTHESIS o 6002 6H20 light gt CESHQO6 602 0 used to fix carbon from the environment and make organic molecules like glucose 0 002 enters and leaves through pores called stomata 0 water is provided from the soil 0 O2 liberated comes from H20 0 Stomata pores that can be opened and closed and tend to be on the underside of leaves 0 Where does the oxygen come from o scientists took two jars and put plants in them 0 in one bell jar they put water and carbon dioxide isotopically labeled 0 in the other they put water isotopically labeled and carbon dioxide 0 They analyzed the atmosphere of the jars after photosynthesis o discovered the oxygen came from the water 0 2 pathways 0 light reactions convert light energy into chem energy in the form of ATP and NADPH H NADPH is like NADH just has a phosphate I NADPH is a coenzyme involved in biosynthetic reactions 0 CalvinBenson Cycle dark reactions carbon dioxide and ATP plus NADPH H produced in the light reactions are used in this cycle to make sugars and other organic molecules I occur in the stroma Chlorophyll is in the thylakoids themselves Light a form of electromagnetic radiation that exists as photons with wavelike properties 0 c speed of ightfrequency times wavelength 0 energy content of a photon is inversely proportional to the wavelength of the light 0 energy of a photon cwavelength o if light strikes a molecule 3 possibilities I reflected I transmitted I absorbed if molecular structure of the molecule is appropriate an electron can be boosted to a higher energy levelquotexcited state o excited electron will drop back down to ground state and release energy 0 in fluorescence the light admitted has a longer wavelength less energetic o Photosynthetic pigments o atom only absorbs o Chlorophyll I remains in the thylakoid membrane I photons can excite electrons from chlorophyll molecules and that electron can be gotten by an electron receptor I excited chlorophyll Chl is a good reducing agent reacts with some oxidizing agent 0 excited electron is shuttled along a series of electroncarrier molecules in the photosynthetic membrane 0 at a protonpumping channel proton translocation occurs resulting in ATP synthesis I resonance energy transfer like a vibrational energy transfer from one chlorophyll to another increases efficiency of the process 0 action spectrum measures rate of photosynthesis as a function of wavelength 0 Noncyclic electron transport uses the 2 photosystems to produce NADPH H together with ATP 0 happens in thylakoid membrane electrons pass through carrier that pumps protons into the interior of the thylakoid oxygen is a byproduct Photosystem l reaction center has chlorophyll a not as energetic as Photosystem I chlorophyll a absorbs blue and red light I electrons go through ferredoxin Fd I electrons ultimately end up in NADPH and electrons get replaced by the electrons from photosystem 2 o Photosystem ll comes before photosystem I and is more energetic I water is split to replace the electrons 0 Cyclic Electron Transport 0 produces ATP but not NADPH just has one photosystem photosystem electron is transferred back to where it came from water is not split just used to make additional ATP 102815 Lecture 14 Photosvnthes cont 0 Noncyclic Electron transport uses both the photosystems o Photosystem ll replenishes electrons of Photosystem l COO 0000 I water splitting complex pulls electrons out of water using energy and then releases oxygen has 4 manganese 5 oxygen and one calcium atom o Photosystems work in tandem 0 Cyclic Electron Transport traps light energy as ATP 0 system provides backup ATP for use in the dark reactions 0 Chloroplasts form ATP chemiosmotically o proton pumping pumps protons into the interior of the thylakoid 0 Dark Reactions CalvinBenson Cycle 0 occurs in the stroma o 002 reacts with ribulose bisphosphate RuBP forming 2 molecules of 3phosphoglyceric acid catalyzed by RuBP o 3 parts to the cycle carbon fixation reduction and sugar production uses ATP and NADPH to make glyceraldehyde3phosphate G3P 0 GBP is a 3carbon sugar phosphate 0 2 steps 0 in a typical leaf most G3P gets recycled into the cytoplasm to form sugars Regeneration of RuBP RuBP is made for glyceraldehyde3phosphate o Phosphorespiration rubisco catalyzes reaction with 02 as well as 002 reaction requires light and uses oxygen reduces efficiency of photosynthesis if the reaction occurs with oxygen instead of carbon dioxide by accident it s called photorespiration RuBP 02 gtglycolate 20 glycolate enters peroxisomes is oxidized and the product enters mitochondria and is broken down releasing 002 oxygenase function of rubisco is favored at high temps and low 002 levels Rubisco probably evolved before 02 existed in the atmosphere currently oxygen is 500x more abundant than 002 selectivity for 002 is improved by a slower catalytic rate easier for the enzyme to distinguish between oxygen and carbon dioxide which is probably why rubisco s reaction rate is slow and why the plant needs so much rubisco rubisco may comprise up to 50 of the total protein in a leaf 0 lnterrelations between metabolic pathways in plants 0 3PG gets bled off from dark reactions to form glycerol and be involved in lipid metabolism or to form pyruvate and be involved in the citric acid cycle 0 RuMP can be bled off to form nucleotides and nucleic acids 0 GBP can be converted to hexoses that can be converted to polysaccharides starch in plants 0 the citric acid cycle uses an intermediate that can be bled off to form amino acids that form proteins 10302015 Lecture 15 Physiology Homeostasis and Temperature Regulation amp Nervous System we have 75 trillion cells in our body there are 200 different types of cells eg neurons heart cells etc physiologists classify cells by how they interact with each other tissue cluster of multiple cells with similar function 0 epithelial surface 0 connective connect organs together 0 muscle 0 nervousbrain tissue organ a group of tissues working together organ system group of organs that have a common function 0 there are 11 systems in our body 0 all are connected 0 work in a common functionality to maintain homeostasis so cells are satisfied organism all the organ systems put together what do cells need to survive o nutrients oxygen gt energy 0 blood vessels are relied upon to transport these things 0 everything is delivered through the digestive respiratory and cardiovascular system c digestive system ensures the food we consume is properly broken down I to be efficient chemical reactions require enzymes I secretion comes from blood or from cells etc I then the food needs to be moved from the digestive system to the circulation to get to cells I pepsin enzyme that functions in digestion o respiratory system we are constantly breathing I the oxygen in your lungs doesn t do anything until it diffuses into the blood CO2 travels through circulation back into the lungs and is exhaled carbs and lipids are used to make atp proteins can be used to make ATP but Renal system metabolizes nitrogenous waste into ureaurine to be excreted o Nitrogenous wastes nucleic acids and amino acids Nervous system Brain is regulating organs Endocrine system also a regulatory system but different level of control Reproductive system ensures life continues Immune system ensures we can fight off pathogens Homeostasis maintenance of constant internal environment sodium glucose pH maintaining 3d shape of protein temp also maintains shape of protein that s why fever is bad Components of homeostatic system to adequately maintain homeostasis I receptor provide info about specific conditions measures does nothing else 0 mostly on organ surfaces especially skin I control center decisionmaker evaluates info from receptors 0 then decides if something must be done by comparing to the norm set point 0 most are in the brain I effectors work to restore the deviation from the set points of the internal environment 0 Temperature Control I temp decrease 0 sense temperature drop from receptors thermal receptors 0 information fed to control center Hypothalamus 0 info goes to effectors skeletal muscles and blood vessels of the skin 0 effectors have effects when skeletal muscles contract uncontrollably they generate heat blood vessels vasoconstrict because decreasing flow of water at surface minimizes its interaction and loss of heat 0 these effects stop when we re back at set point 0 NEGATIVE FEEDBACK MECHANISM stability I Classification of ANimals o endotherms all mammals and birds regulate body temp by generating metabolic heat andor preventing heat loss 0 ectotherms reptiles etc do not have the ability to control their own body temperature it mimics whatever the external temperature is o POSITIVE FEEDBACK unstable we have very few of these mechanisms eg lactation females can keep breastfeeding as long as they want also the menstrual cycle in females OOOOO Nervous Svstem 0 function of the nervous system everyting o constantly receiving information input 0 processing that information what does it mean processing 0 sending information out output 0 neurons billions of them make up the nervous system able to communicate with each other and with other cells in the body through electrical and chemical signals O O O excitable cells exhibit electrical activities which are extremely quick lots of branches and one long thing with more branches on them can be extremely long Components of a neuron O Soma cell body circular shape main component of the cell aka perikaryon or cell body 5140 micrometer diameter abundant protein synthesis organelles Dendrites special branches where electrical signals are received lots on one neuron because the neuron receives many signals from many different axon where electrical activity is generated and sent out I most neurons only have one axon but many dendrites I aka nerve fiber I has lots of microtubules for transport axon terminals filled with neurotransmitters I neurotransmitters initiate activities in other neurons myelin insulates the axon to speed up electrical activities I schwann cells produce myelin sheaths I nodes of ranvier gaps in myelin sheaths along the axon very important in the propagation of electrical activities
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