Week 8 Notes
Week 8 Notes Bio 208
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This 7 page Class Notes was uploaded by Kylie McLaughlin on Sunday October 18, 2015. The Class Notes belongs to Bio 208 at Northern Illinois University taught by Dr. Ed Draper in Fall 2015. Since its upload, it has received 25 views. For similar materials see Fundamentals of Cell Biology in Biological Sciences at Northern Illinois University.
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Date Created: 10/18/15
Week 8 Notes Chapter 9 cont Electron Transport Chain ETC the electron transport chain is the inner membrane cristae of the mitochondrion most of the chains components are proteins which exist in multiprotein complexes high energy electrons from NADH and FADH2 are transferred to the top of the chain eectrons drop in free energy as they go down the chain and are nally passed to 02 forming H20 the electron transport chain generates I ATP directly Transoort of Electrons thouoh ETC generates as H gradient eectron transfer in the electron transport chain causes proteins to pump H from the mitochondrial matrix to the intermediate space eectron transport NADH gt 02 leads to the formation of energy stored in an H gradient across a membrane couples the redox reactions of the electron transport chain to ATP synthesis Chemiosmosis the EnerovCouolino Mechanism when H moves back across the inner membrane it passes through a protein complex ATP synthase ATP synthase uses the exergonic ow of H back into the matrix to drive the endergonic phosphorylation of ADP this is an example of chemiosmosis use of energy in a H gradient to drive cellular work 0vera process is called Electron Transoort throuoh ETC generates a H gradient 1 NADH transfers its electrons to a higher point in the ETC than FADH2 2 NADH electrons pass through 3 quotpumping stationsquot gt 3 ATP per NADH 3 FADH2 electrons pass through 2 quotpumping stationsquot gt 2 ATP per FADH2 Summary ATP yield per glucose following complete oxidation and oxidative phosphorylation 1 Glycolysis SLP 2 ATP 2NADH 6 4 ATP gt have to go through carriers different in each cell why the production of ATP can sometimes be 6 and can sometimes be 4 Oxidation 2NADH 6 ATP Krebs cycle SLP 2 ATP 6NADH 18 ATP 2FADH2 4 ATP a Total 38 36 JUN Fermentation and Anaerobic Respiration allow cells to make ATP in the absence of oxygen most cellular respiration requires 02 to produce ATP without 02 the electron transport chain will cease to operate gycoysis couples with anaerobic respiration or fermentation to produce ATP gycoysis is really ancient process in all organisms Fermentation consists of glycolysis plus reactions that regenerate NAD which can be reused by glycolysis two common types are alcohol fermentation and lactic acid fermentation in alcohol fermentation pyruvate is converted to ethanol in two steps 1 Releases 02 2 Produces ethanol alcoho fermentation by yeast is used in brewing winemaking and baking in lactic acid fermentation pyruvate is reduced by NADH forming lactate as an end product with no release C02 lactic acid fermentation occurs in human muscle cells to generate ATP when 02 is scarce lactic acid fermentation is used by some fungi and bacteria to make cheese and yogurt virtually any food proteins lipids complex carbohydrates can be metabolized via glycolysis and the Krebs cycle and yield energy key intermediates 1 Glycerol 2 Pyruvate 3 AcetylCoA Step 3 in glycolysis important regulator of process rst irreversible step phosphofructokinase PFK is an enzyme that is regulated by reaction 3 is of glycolysis is catalyzed by PFK which is the rst committed step in cell respiration high AMP or high ADP stimulatesincreases PFK activity high ATP or high citrate inhibitsdecreases PFK activity feedback inhibition Oxidation of Glucose most reduced least oxidized most energy ATP from SLP reducing power glucose 6C I glycolysis 2ATP 2NADH I pyruvate 3C x 2 I ox of pyruvate 2 NADH I acetylCoA 2C x 2 I citric acid cycle 2 ATP 6NADH 2FADH2 I 4C02 leased reduced most oxidized least energy Guest Speaker 101415 very important that ion dissociation across a membrane happens regularly bacteria s have ion disequilibrium antiporter tertiary transporter exchanges amino acids pumps in extracellular amino acids gutamine highest concentration in blood serves major metabolic role very important to cancers chews it up and creates a lot of ammonia essential amino acids are the ones we can39t make ourselves have to get from food iver cancer on rise because of hepatitis C especially in Asia and in subSaharan Africa in Africa a atoxin major cause of liver cancer that comes from fungus 17 known glutamine transporters families gycoysis way for organisms to metabolize glucose rapidly to make ATP bacteria use it a lot every living organism uses it 2 pyruvate molecules are made next is redox reaction gt coat pyruvate to make alcohol inefficient pathway start with glucose gt gets phosphorylated and is trapped inside the cell and sets up covalent phosphate step 3 adds another ATP gt get dephosphorylated sugar next is split into 23 carbon molecules step 7 gt generates 2 ATP step 10 gt generate ATP phosphoryated molecules have higher energy and bind with ADP to make ATP turned on with low oxygen tension Citric Acid Cycle can get up to 36 ATP yields a lot more than glycolysis pyruvate ows into it forming reducing equivalents donate protons oxidative phosphorylation set up gradients that drive formation of ATP in cancer biology any molecule that is formed and can feel into the TCA cycle Ex glutamine warburg effect amping up of glycolysis in cancerous tissue turned on under normal oxygen tension warburg won nobel prize was Krebs mentor PET positron emission functional or metabolic imaginginformation inject radioactive glucose and spots on PET scan shows cancertumors CAT anatomic information PETCT high resolution and metabolic imaging all based on Warburg effect gutamine H2N gt used to make RNA DNA gutamate gt msg headache main transaminase in central nervous system cancer turns on glycolysis to generate NADPH and ribose 5 phosphate used to make DNA RNA NAD by pentose phosphate pathway causes everything to back up intermediates are backed up energy for tumorscancer is through glutamine that drives TCA cycle cold and u get perforation of white blood cells do same thing as cancer but different is these get turned off and cancer does not TCA cycle rst step is actually reversible pamitate fatty acid when 2 cells lives next to each other like 2 countries several different cell types in tumors in many cancers lDHl mutant or IDH2 mutant and able to use a drug for these now initial trials show very effective Chapter 10 Photosvnthesis Autotrophs quotselffeedersquot sustain themselves without eating anything derived from other organisms amost all plants are photoautotrophs using the energy of sunlight to make organic molecules photosynthesis occurs in plants algae certain other unicellular eukaryotes and some prokaryotes Heterotroph5con5umer5 obtain their organic material from other organisms provide oxygen we need to breathe respiration in mitochondria is catabolic photosynthesis in chloroplasts is anabolic H20 02 and C02 are substrates and products D C6H1206 glucose 6C02 39 6C02 6H20 energy Chloroplasts the sites of photosynthesis in plants most if not all photosynthesis happens in the leaves choropasts are structurally similar to and likely evolved from photosynthetic bacteria structura organization of these organelles allows for the chemical reactions of photosynthesis hydrophobic and on the leaf surface reduce loss of water stomates are pores in the epidermis they open and close to allow gas movement in and out of the leaf choropasts are found mainly in cells of the mesophyll the interior tissue of the leaf each mesophyll cell contains 3040 chloroplasts a chloroplast has an envelope of two membranes surrounding a dense uid called the stroma contains ribosomes DNA and calvin cycle enzymes are connected sacs in the chloroplast which compose a third membrane system thylakoids may be stacked in columns called grana thylakoid membranes contain light reaction proteins and ETC photosynthesis reverse of cellular respiration is a complex series of reactions that can be summarized as the following equation 6C02 12H20 light energy C6H1206 6C02 6H20 Two Staoes of Photosvnthesis 1 Light reactions Occur in thylakoids Pigments chlorophylls carotenoids absorb light energy ATP is made chemiosmosis photophosphorylation NADIH reducing power is made electrons needed to reduce NADP come from H20 water is split and how we get oxygen apem e 02 is waste product 2 Calvin cycle quotdark reactionsquot or quotlight independent reactionsquot Happens in stroma Uses soluble enzymes in stroma quotcarbon fixationquot reduction C0 gt sugars glucose Uses ATP and NADPH made in light reactions Endergonic process rhrDonom Photosynthesis as a Redox Process Energy 6C02 6H20 gt C6H1206 6C02 6H20 gt 6C02 becomes oxidized 6C02 gt C6H 1206 becomes reduced The Nature of Sunlight ight is both a has a wavelength A and a photon shorter A greater energy gamma gt xrays gt UV gt visible gt microwaves gt radio waves coor is related to A blue 475nm green 550nm red 700nm sunight quotwhite lightquot is rich in photons of all visible A pigments are substances that absorb visible light different pigments absorb photons of different wavelengths wavelengths that are not absorbed are re ected or transmitted which gives an object its color Chlorophyll a and b a long hydrophobic tail is embedded in thylakoid membranes the quotheadquot is a hemilike ring with a feature of almost all pigments subtle differences between chla and chlb gt different absorption chorophyls associate with proteins to form Carotenoids are accessory pigments they protect chlorophylls from photodamage by absorbing excess light an is a graph plotting a pigments light absorption versus wavelength the absorption spectrum of chlorophyll a suggest that violetblue and red light work best for photosynthesis an pro les the relative effectiveness of different wavelengths of radiation in driving a process aerobic bacteria can only grow in the presence of oxygen when a pigment absorbs light it goes from a to an which is unstable higher energy electrons can be passed around when excited electrons fall back to the ground state photons are given off an afterglow called fuorescence is the emission of a photon at a longer wavelength less energy if illuminated an isolated solution of chlorophyll will uorescence giving off light and heat fuorescence is a wasteful process Photosystems capture energy in excited state electrons These pigmentprotein complexes are embedded in thylakoids major components of photosystems are 1 of about 100 to 200 chorophys and associated proteins LHC or lightharvesting complex 2 A which is a special chlorophyll capable of redox RC can gainlose rea electrons not just transfer the excited state P680 is the RC in PSII P700 is the RC in PSI 3 1 acceptor gains an electron and becomes reduced