Respiration and Photosynthesis
Cellular Respiration Glycolysis The Krebs Cycle Electron Transport Chains Anabolic Pathway Photosynthesis Calvin Cycle
Flow of Energy Energy is needed to support all forms of life We have talked about that energy is transferred from producer to consumer but how? How does light energy from the sun get transferred into usable forms of energy?
The Short Answer Plants use sunlight to go through photosynthesis Photosynthesis generates Oxygen and organic molecules used by the mitochondria as fuel for respiration Respiration breaks down that fuel to generate ATP which is the molecule that drives cellular work
Catabolic Pathways Catabolic (break down complex molecules) pathways create energy by oxidizing organic fuel Cellular Respiration-The chemical process that generates most of the energy in the cell Aerobic Respiration- oxygen is consumed as a reactant along with organic fuel (aerobic=air) Fermentation- partial degradation of sugar or other organic fuels that occurs without the use of oxygen Anaerobic- without air
Glucose Glucose is a sugar C6H12O6 The typical formula for the break down in Glucose usually has the products of CO2 H2O and Energy in the form of ATP and Heat C6H12O6 + 6O2 > 6CO2 + 6H2O + Energy
Misnomer about Catabolic Pathways They do not do they work of the cell Move the cell Pump molecules across a membrane Ect. They just provide the Fuel in order to preform these functions
Cellular Respiration Think of this as 3 stages Glycolysis, The Krebs (aka Citric Acid) Cycle, & Electron Transport
Glycolysis and Its Reactants Glycolysis- literally means glucoses splitting so this is the stage of cellular respiration where glucose molecules are split up Enzymes split the glucose molecules into 2 Pyruvate molecules (or Pyretic acid) In order to split the Glucose there is energy needed so 2ATP molecules are used to start off the reaction The ATP break a Phosphate off to release the energy needed to start the reaction off and form 2 ADP (adenosine diphosphate)
Glycolysis Products In order for glycolysis to be effective it has to produce more energy then it takes in The key products formed from glycolysis is 4 ATP, 2 NADH, 2H +, 2 Pyruvate & 2 H2O
Glycolysis Net Payout Net pay is how much did you profit If I pay someone $500 and they made me $750 then I only profited $250 over my investment of $500 Same concept with Glycolysis we used resources to start the process so they will be counted against the product to form the net profit
Krebs Cycle The Pyruvate travels to the mitochondria where the Krebs cycle takes place 3 Carbon Pyruvate Before the Krebs cycle the 2 Pyruvate combine coenzyme A This reaction produces acetyl-coa The other product are CO2 & 2NADH
Krebs Cycle Acetyl-CoA is a 2 carbon molecule it combines with a 4 carbon molecule called oxaloacetate (OAA) this produces citric acid a 6 carbon atom Citric acid goes through a series of reactions that release energy in the forms of NADH, ATP, and FADH2 OOA is then regenerated and reused and the cycle is repeated for the other pyruvate made in glycolysis http://www.youtube.com/watch?v=fgxnh087jik
The Results Up To This Point After the 2nd time through the Krebs cycle the original glucose molecule has been completely broken down 16 energy carrier molecules 4 ATP 10 NADH 2 FADH2
Electron Transport Chain Electron Transport Chain - a collection of molecules embedded in the inner membrane of the mitochondrion All the folds in the mitochondrion allows more surface area which allows more proteins to be added to the surface As an electron is transported along the chain, the carries (NADH & FADH2) alternate between oxidizing and reducing as the donate and take on electrons Through out the movement of the electron H + ions are pumped out of the organelle creating a concentration gradient
NADH looses its H + ion FADH2 loses both of its H + ions 1 H + is released out of the mitochondrion 1 H + is used up the chain to combine oxygen (why this is aerobic respiration) to form H2O
Electron Transport Chain Continued ATP Synthesis- the creation of ATP molecules ATP Synthase- and enzyme that makes ATP from ADP and Inorganic phosphate It takes the H + gradient that is produced and uses the energy of the ions to allow free ADP and Phosphorous ions to form together to form ATP
What is our overall product?
Anaerobic Respiration No oxygen Is the sole source of ATP in anaerobic bacteria Starts off like cellular respiration using glycolysis to produce 2 ATP molecules and 2 Pyruvate Then it uses Fermentation to produce ethanol and NAD+ Which then fuels glycolysis this process does not net the huge amount of ATP that cellular respiration does
Fermentation 2 pathways Alcoholic Fermentation Products: 2 Ethanol & 2 CO2 Lactic Acid Fermentation Products: 2 Lactates Both replenish NAD + for glycolysis Both net yield 2 ATP molecules per glucose
Ways Plants Get Energy Photosynthesis- the process plants uses to convert light energy and convert it to chemical energy that is stored in sugar Autotrophs- self feeders, they make their own energy Heterotrophs- obtain energy from consuming organic materials (with plants think of decomposers)
Photosynthesis Sites The Mesophyll of the leaves contain Chloroplast Chloroplast-a plastid that contains chlorophyll and in which photosynthesis take place Mesophyll- the tide in the interior of the leaf CO2 enters and exits the leaves through pores called stomata Water is absorbed through the roots and other non photosynthetic parts of the plant
Mesophyll Cells 30-40 chloroplasts Chloroplast Stroma- the envelope of 2 membranes surround a dense fluid Thylakoids- suspended sacked which segregate the stoma from the thylakoid space Chlorophyll- free pigment that gives leaves it color, resides in the thylakoid membranes
Photosynthesis Reaction 6 CO2 + 12H2O + Light Energy > C6H12O6 + 6 O2 + 6 H2O The process in which plants make glucose is called the Calvin Cycle Calvin Cycle takes CO2 and uses it to make a 3-C sugar this by sunlight (provides ATP and NADPH) Consist of 3 parts Carbon Fixation Reduction Regeneration
Calvin Cycle Carbon Fixation A CO2 molecule combines with a 5-Carbon acceptor molecules and makes a 6-Carbon molecule (RuBP or ribulose-1,5-bisphophate) RuBP is split into 2 molecules of a 3-Carbon molecule (3-PGA)
Calvin Cycle Reduction ATP & NADPH are used to convert 3-PGA into a 3 carbon sugar (glyceralheyde-3-phosphate or G3P)
Calvin Cycle Regeneration Some G3P molecules go make glucose whole others are recycled to regenerate RuBP acceptors Regeneration requires ATP