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Cellular Respiration vs. Photosynthesis Willoughby
Transcript of Cellular Respiration vs. Photosynthesis Willoughby
Jan van Helmont began the research in the mid-17th century when he measured the mass of the soil used by a plant and the mass of the plant as it grew. After noticing that the soil mass changed very little, he hypothesized that the mass of the growing plant must come from the water, the only substance he added to the potted plant.
First Law of Thermodynamics in Photosynthesis
6H2O + 6CO2 --light--> C6H12O6+ 6O2
First Law Of Thermodynamics:
Cellular Respiration Sequences
Organisms are heterotrophs.
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy and store it in the bonds of sugar.
Organisms that participate are autotrophs.
The sun is the primary energy source.
Soon after, Joseph Priestley discovered that when a candle was placed in an enclosed jar, the candle would burn out very quickly, making him the second person to discover oxygen in 1774, but the first to published it. This proves that the air contains oxygen.
In 1796, Jean Senebier, demonstrated that green plants consume carbon dioxide and release oxygen under the influence of light. Soon afterward, Nicolas-Théodore de Saussure showed that the increase in mass of the plant as it grows could not be due only to uptake of CO2 but also to the incorporation of water. Thus, the basic reaction by which photosynthesis is used to produce food (such as glucose) was outlined.
The next chapter in the story of photosynthesis was by Jan Ingenhousz his conclusion was that in light, plants produce a gas called oxygen, but they don't in the dark.
Located in chloroplast.
Cellular respiration is the set of the metabolic reactions and processes to convert biochemical energy from nutrients into ATP.
Takes place in cytoplasm and mitochondria.
Energy sources include ATP and glucose.
Cellular respiration was not discovered by any one scientist; instead, various scientists over time have contributed to our understanding of cellular respiration. The most famous of the scientists is Hans Krebs, who discovered the Krebs Cycle, a part of the cellular respiration process.
The other steps include glycolysis and the electron transport chain, which were discovered to varying degrees by multiple scientists.
During vigorous exercise, oxygen is consumed faster than it is needed. Additional ATP energy is provided to the muscles by glycolysis and the result is a buildup of lactate in the muscles.
Occurs when oxygen is not present.
Also called fermentation.
Cells without oxygen available need to regenerate NAD+ from NADH so that in the absence of oxygen, at least some ATP can be made by glycolysis.
Cellular respiration is a catabolic process that includes both aerobic respiration and anaerobic respiration.
Aerobic respiration occurs when oxygen is available.
Requires oxygen to generate ATP.
The pyruvate produced in glycolysis undergoes further breakdown through aerobic respiration. Aerobic respiration is divided into two processes: the Krebs cycle, and the Electron Transport Chain, which produces ATP through chemiosmotic phosphorylation.
Photosynthesis is an anabolic process. Anabolic processes are constructive. Light energy is used to synthesize a complex molecule, glucose, from simpler ones (carbon dioxide and water).
Does not require oxygen, instead, oxygen is produced.
Cellular respiration is exergonic. meaning energy is released.
Endergonic because energy is absorbed/captured/needed in order to work. Photosynthesis captures light energy in order to form carbohydrates.
Second Law of Thermodynamics:
Energy cannot be created nor destroyed.
Every energy transformation increases the entropy of the universe. There is always some loss of useful energy.
During cellular respiration, the energy in the bonds of glucose is released and is transformed into new molecules (ATP), motion, and heat energy.
First Law in Cellular Respiration:
Second Law in Cellular Respiration:
Whenever there is a change in energy form, it is not 100% efficient. Some energy from cellular respiration is lost as heat.
Cellular respiration is exothermic because energy is released. Tends to increase entropy.
Second Law of Thermodynamics in Photosynthesis
During photosynthesis, light energy from the sun is transformed into chemical energy stored in the bonds of glucose.
Photosynthesis is endothermic because it requires energy. Tends to decrease entropy.
In photosynthesis, the plant is not 100% efficient at converting light energy. over 95% of the light energy is lost due to reflection, photons out of the 400-700 nm range, incomplete absorption etc.
In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-carbon molecule called pyruvate.
This change is accompanied by a net gain of 2 ATP molecules from substrate level phosphorylation and 2 NADH molecules.
Glycolysis occurs in the cytoplasm (cytosol) and does not require oxygen.
Pyruvate produced by glycolysis enters the matrix of the mitochondria. Oxygen is required.
Carbon dioxide is removed from each of the pyruvate molecules for a total of two molecules of CO2.
Each of the two-carbon compounds are oxidized by NAD+ to become acetate. Pyruvate is oxidized and NAD+ is reduced.
Coenzyme A is attached to each acetate producing two acetyl CoA molecules.
2 pyruvate + 2NAD+ + 2CoA -> 2acetly-CoA + 2NADH + 2H+ + 2CO2
The 8 step cycle completes the oxidation of glucose. the 6 carbon atoms of glucose leave the process as CO2.
The Acetyl group from acetyl-CoA condenses with oxaloacetate to form the 6 carbon molecule citrate.
Each turn of the cycle yields 1 ATP, making a total of 2 ATP because two turns of the cycle are required. 2 CoA, 6 NADH, 2 FADH2, 4 CO2 and 2 oxaloacetate's are produced.
2Oxaloacetate + 2acetyl-CoA + 2ADP + 2Pi + 6NAD+ + 2FAD -> 2CoA + 2ATP + 6NADH + 2FADH2 + 4CO2 + 2oxaloacetate
Electron Transport and Oxidative Phosphorylation
The electron transport chain allows the release of the large amount of chemical energy stored in reduced NAD+ (NADH) and reduced FAD (FADH2). The energy released is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH2).
ETC consists of a series of electronegative electron acceptors embedded in the inner mitochondrial membrane. The components of the chain pass electrons down an energy gradient to oxygen which picks up a pair of hydrogen ions and forms water. Free energy lost by electron pair during transport is used to pump protons into the intermembrane space. A proton motive force is the potential energy stored in the form of a proton electrochemical gradient. The enzyme, ATP synthase, uses the potential energy from the proton electrochemical gradient to drive the synthesis of ATP. 32 molecules of ATP
are synthesized. A total of 36 ATP molecules per glucose.
If no oxygen present, then anaerobic respiration will take place->a lot less energy produced, only 2 ATP.
lactic acid is toxic and causes cramps.
Darkness, cold temperatures, hot temperatures, light intensity, nutrients, water, and CO2 concentration.
Dark Reactions: Calvin Cycle
Uses free energy of ATP and the reducing power of NADPH to synthesize organic carbohydrate from CO2 and H2O.
2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light -> 2 NADPH + 2 H+ + 3 ATP + O2
The aim is to produce ATP from ADP and NADPH from NADP+. Also to harvest hydrogen so that carbon dioxide can be reduced to form a carbohydrate in the second series of reactions. The production of ATP using light is called photophosphorylation.
Water splits into two electrons, two hydrogen ions and an oxygen atom.
A photon strikes photosystem II. P680 absorbs light at a wavelength of 680 nm. The exited electron is transferred to the primary electron acceptor.
The energy is actually used to pump hydrogen ions from the stroma across the thylakoid membrane. This creates an electrochemical gradient and drives ATP synthesis.
Another photon strikes photosystem I which absorbs light at 700 nm. The enzyme NADP+ reductase reduces NADP+ to NADPH.
Cyclic electron flow only produces ATP (without water), non cyclic produces ATP and NADPH (with water).
3RuBp + 3 CO2 + 9 ATP + 6 NADPH + 5H2O -> + 9 ADP + 8 Pi + 6 NADP+ + G3P + 3RuBp
3 stages: Carbon fixation
regeneration of RuBisCo
1. A five-carbon sugar molecule called RuBP, is the acceptor that binds CO2 dissolved in the stroma. This process, called CO2 fixation, is catalyzed by the enzyme RuBP carboxylase, forming an unstable six-carbon molecule. This molecule quickly breaks down to give two molecules of the three-carbon 3-phosphoglycerate (3PG), also called phosphoglyceric acid (PGA).
2. The two 3PG molecules are converted into glyceraldehyde 3-phosphate (G3P, a.k.a. phosphoglyceraldehyde, PGAL) molecules, a three-carbon sugar phosphate, by adding a high-energy phosphate group from ATP, then breaking the phosphate bond and adding hydrogen from NADH + H+.
3. Three turns of the cycle, using three molecules of CO2, produces six molecules of G3P. However, only one of the six molecules exits the cycle as an output, while the remaining five enter a complex process that regenerates more RuBP to continue the cycle. Two molecules of G3P, produced by a total of six turns of the cycle, combine to form one molecule of glucose.
Photosynthesis and cellular respiration are interdependent
They both have ETC's and participate in chemiosmosis
They both demonstrate energy transformations and follow the laws of thermodynamics.
The Calvin cycle includes reactions that are similar to reactions in cellular respiration but that occur in reverse.
The proteins, quinones and cytochromes of the electron transport chains in photosynthetic membranes and in respiratory membranes are similar in structure
and, in some cases, are exactly the same.
Energy is produced.
Photosynthesis and Cell Respiration both involve the exchange of the gases; oxygen and carbon dioxide
The equations are reverse.