Photosynthesis and Cellular Respiration
Photosynthesis in natureAccording to the way they obtain energy, all living things can be divided into : Autotrophs: producers; obtains organic food without eating other organismsHeterotrophs: consumers; obtains organic food by eating other organisms or their by-products (includes decomposers)
How are they connected?HeterotrophsAutotrophsmaking energy & organic molecules from light energymaking energy & organic molecules from ingesting organic moleculesWheres the ATP?oxidation = exergonicreduction = endergonic
What does it mean to be a plplantantNeed tocollect light energy
store light energy
need to get building block atoms from the environment C,H,O,N,P,K,S,Mgproduce all organic molecules needed for growthcarbohydrates, proteins, lipids, nucleic acidsATP
The chloroplastSites of photosynthesisPigment: chlorophyllPlant cell: mesophyllGas exchange: stomataDouble membraneThylakoids, stack-granum Stroma-fluid-filled interior
PhotosynthesisLight reactionslight-dependent reactionsenergy conversion reactionsconvert solar energy to chemical energy
Calvin cyclelight-independent reactionssugar building reactionsuses chemical energy (ATP) to synthesize glucose (C6H12O6) Its not the Dark Reactions!
Light reactionsConvert solar energy to chemical energyATPNADPHWhat can we do now? energy reducing power build stuff !! photosynthesis ATP
The Calvin CycleWhoops! Wrong Calvin1950s | 1961
How is that helpful?Want to make C6H12O6 synthesisHow? From what? What raw materials are available?CO2NADPHNADPreduces CO2carbon fixation
RuBisCo Enzyme which fixes carbon from airribulose bisphosphate carboxylase the most important enzyme in the world!it makes life out of air!definitely the most abundant enzymeIm green with envy! Its not easy being green!
Putting it all togetherSugar BuildingReactionsEnergy BuildingReactionsPlants make both:energyATP & NADPHsugarsO2H2OsugarsCO2ADPATPNADPHNADP
Energy cyclePhotosynthesisCellular RespirationO2CO2plantsanimals, plantsATPThe Great Circle of Life,Mufasa!even though this equation is a bit of a lie it makes a better story
2007-2008You can grow if you Ask Questions!
2006-2007Whats the point?The point is to make ATP!ATPCell Respiration
What is Cell Respiration? A series of reactions that break down molecules to produce energy OR the catabolism of glucose to produce ATPCO2 + H2O + heatRESPIRATION = making ATP (& some heat)by burning fuels in many small stepsCO2 + H2O + ATP (+ heat)enzymesATP
The reactions are called REDOX Oxidation & reductionOxidationadding Oremoving H releases energyexotermicReductionremoving Oadding H stores energyendotermic
(1)Glycolysis Breaking down glucose glyco lysis (splitting sugar)
but its inefficient generate only 2 ATP for every 1 glucoseoccurs in cytoplasmIn the cytoplasm? Why does that make evolutionary sense?Thats not enough ATP for me!
Is that all there is?Not a lot of energyfor 1 billon years+ this is how life on Earth survivedno O2 = slow growth, slow reproductiononly harvest 3.5% of energy stored in glucosemore carbons to strip off = more energy to harvestHard way to make a living! glucose pyruvate6C
NADHpyruvateacetyl-CoAlactateethanolNAD+NAD+NADHNAD+NADHCO2acetaldehydeH2OKrebscycleO2lactic acid fermentationwith oxygenaerobic respirationwithout oxygenanaerobic respirationfermentationHow many types of Cell Respiration? which path you use depends on who you arealcohol fermentation
Fermentation (anaerobic)Bacteria, yeastAnimals, some fungibeer, wine, breadcheese, anaerobic exercise (no O2)back to glycolysisback to glycolysis
Alcohol FermentationCount the carbons! Dead end processat ~12% ethanol, kills yeastcant reverse the reactionGenerates only 2 ATP! bacteria yeastback to glycolysis
Reversible processonce O2 is available, lactate is converted back to pyruvate by the liverGenerates only 2 ATP Lactic Acid FermentationCount the carbons! animals some fungiback to glycolysis
Pyruvate is a branching pointPyruvatemitochondriaKrebs cycleaerobic respirationfermentationanaerobic respiration
ATP accounting so farGlycolysis 2 ATP Krebs cycle 2 ATP
A working muscle recycles over 10 million ATPs per secondTheres got to be a better way!I need a lot more ATP! It is called ELECTRON TRANSPORT CHAIN and makes LOTS of ATP !!!
Counting the energy released in AEROBIC RESPIRATIONGlycolysis brings : 2 ATP Krebs Cycle brings: 2 ATP)Electron transport brings: From glycolysis = 6ATP From acetyl CoA = 6ATP From Krebs cycle = 22 ATP 38 TOTAL ATP/one molecule of glucose
*So, in effect, photosynthesis is respiration run backwards powered by light.Cellular Respirationoxidize C6H12O6 CO2 & produce H2Ofall of electrons downhill to O2 exergonic
Photosynthesis reduce CO2 C6H12O6 & produce O2boost electrons uphill by splitting H2Oendergonic
****CO2 contains little energy because it is fully oxidizedReduce CO2 in a series of steps to synthesize a stable energy storage molecule*****Movement of hydrogen atoms from glucose to water**Why does it make sense that this happens in the cytosol?Who evolved first?*So why does glycolysis still take place?*Count the carbons!!
Lactic acid is not a dead end like ethanol. Once you have O2 again, lactate is converted back to pyruvate by the liver and fed to the Krebs cycle.****