BIOL 1500 Study Guide - Final Guide: Light-Independent Reactions, Citric Acid Cycle, Cellular Respiration
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Explain how breathing and cellular respiration are related
- When you breath you inhale oxygen In breathing , you inhale oxygen, which is used in
cellular respiration, in the Kreb's cycle, and also in the electron chain to accept oxygen
-Waste product of CR is carbon dioxide released as citric acid is broken down (in the
Citric acid cycle of Kreb's Cycle), and carbon molecule attaches to an O2 to exit the body
as carbon dioxide.
Describe the roe of redox reactions in photosynthesis and cellular respiration
oOxidation is the loss of electrons or the increase in oxidation state by a molecule.
oReduction is the gain of electrons or a decrease in oxidation by a molecule.
oCellular respiration depend on the reduction of NAD+ to NADH and the oxidation of
NADH to NAD+.
oThe NADH are then used to fuel the proton pump and create a concentration
gradient in the intermembrane space. In
oPhotosynthesis the oxidation of CO2 to glucose
o* cellular respiration oxidizes glucose to CO2 and oxygen to water, and photosynthesis
oxidizes CO2 to glucose and water to oxygen
Compare and contrast the process and location of cellular respiration and photosynthesis.
1) both involve electron transport chains.
2) Chemiosmosis allows ATP synthase to produce ATP.
3) Both take place at some point within an organelle (mit. = CR, chloroplast= photo.)
4) Both utilize ATP for energy at some points.
5) Both provide power for cellular activities.
1) Cellular respiration depends on oxygen as a substrate.
2) Photosynthesis utilizes 2 electron transport chains (not just 1).
3) In Photo. , energy is provided by photons and not catabolic processes as in cell. resp.
4) Photosynthesis involves the production of NADPH (CR involves NADH and FADH2)
5) Photosynthesis involves CO2 and H20 as substrates (splitting h20 provides the electrons for
Describe the overall process of the light reactions and the Calvin cycle, noting products
reactants and locations of every major step.
oCalvin cycle three phases: carbon fixation, reduction, and regeneration of RuBP
(the CO2 acceptor).
oThe Calvin cycle relies on the light reactions to provide the required ATP and NADPH.
oThe Calvin cycle occurs in the stroma of the chloroplast
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o CO2 and H2O react to form the 3-carbon sugar phosphate (or triose phosphate)
molecule, G3P (glyceraldehyde-3-phosphate)
o3 CO2 + 6 NADPH + 5 H2O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2
H+ + 6 NADP+ + 9 ADP + 8 Pi
oCarbon fixation stage: CO2 is bound to ribulose bisphosphate by the enzyme rubisco to
form a 6-carbon product, break down into two, 3-carbon compounds.
oReduction stage: carbon compounds undergo additional phosphorylation & form sugar
product of G3P.
oRuBP acceptor: must be regenerated in order to once again be incorporated with a
CO2 to initiate the phase one fixation step
Explain how oxygen gas is produced in photosynthesis.
Light energy absorbed by photosystem II is used to split a molecule of water
Describe how CO2 is incorporated into sugars during photosynthesis.
6CO2 + 6H2O -----> C6-H12-O6 + 6O2 (C6-H12-O6 = Glucose molecule)
Compare the reactants and products of the light reactions and the Calvin cycle
oLight reactions: water is broken down into 2 hydrogen ions by photolysis. ATP produced
when electrons move down the 1st electron carrier then NADP reduced when electrons
move down the 2nd electron carrier.
oCalvin cycle: CO2 taken into the cycle & reacts with ribulose biphosphate (RUBP) to
produce Glycerate 3 phosphate (GP), ATP ADP. At the same time Reduced NADP
NADP, reactions turns GP into triose phosphate (TP). Some TP turned into
carbohydrates & other carry on the cycle.
Compare the reactants, products, energy yield and cellular location of the three stages of
oGlycolysis (cytoplasm outside of the mitochondria) reactant is glucose, product pruvic
acid & energy yield = 2 ATP
oCitric Acid Cycle (matrix) reactant is acidic acid, product 2 carbon dioxide & energy
yield = 2 ATP
oElectron Transport Phase (Crista of the mitochondria) reactant is NAD, product ATP &
energy yield = 38 ATP
Over all chemical equation for cellular respiration
oC6H12O6 6CO2 + 6H2O + ATP
Explain how the energy in a glucose molecule is released during cellular respiration
Glycolysis: Glucose to Pyruvic Acid (2), 2 ATP, 2 NADH
2. Kreb's Cycle: 3 NADHs, 1 ATP, 1 FADH2 multiply two which equals 6 NADHs, 2 ATP, and 2
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