Catabolic Pathways
Cells break down glucose and other organic fuels in order to create ATP. |
Fermentation is a process that results in the partial breakdown of glucose to ATP without the use of oxygen. |
Aerobic respiration uses oxygen as a reactant while in anerobic processes it uses a different reactant such as sulfur. |
The cell can tap into the energy stored in food particles through redox reactions, where electrons completely shift from one substancxe to another. |
Oxidation is the loss of electrons from a substance while a reduction is the adding of electrons to another. |
During aerobic respiration, glucose is oxidized to CO2 and O2 is reduced to H2O. |
Electrons are usually passed first to NAD+ forming NADH, the electrons then move to the electron transport chain, which conducts them to O2 in energy releasing steps. |
The three stages of Aerobic respiration are: Glycolysis, the Kreb Cycle, and Oxidative Phosphorylation (ETC) |
Photosynthesis converts light energy to food.
In eukaryotes that are autotrophs such as plants, photosynthesis occurs in chloroplasts. |
A chloroplast is an organelle containing thylakoids, stacks of thylakoids form grana. |
Photosynthesis equation: 6CO2 + 12H2O + Light Energy ----> C6H12O6 + 6O2 + 6H2O |
Light reactions in the thylakoid membrane split water, releasing O2. |
The Calvin cycle in the stroma forms sugars from CO2. |
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Glycolisis
Glycolisis splits a glucose molecule into two pyruvate molecules through a series of reactions. |
Pyruvate then goes on to be part of the citric acid cycle. |
Glycolysis nets 2 ATP and 2 NADH per glucose molecule. |
The Kreb Cycle
In eukaryotic cells, after glucose has been split into two pyruvate, the pyruvate is then oxidized to acetyl CoA. |
The acetyl CoA then enters the Kreb Cycle and is further oxidized. |
Glycolysis + Kreb connect to Metabolic Pathways
Catabolic pathways funnel electrons from many kinds of organic molecules to cellular respiration. |
Amino acids of proteins must be deaminated before being oxidized. |
Fatty acids undergo deta oxidizaation to two-carbon fragments and then enter the Kreb cycle as acetyl CoA. |
Light reactions convert solar energy to chemical
Light is a form of electromagnetic energy, the colors we see as visible light include the wavelengths that drive photosynthesis. |
Chlorophyll a is the main pigment of photosynthesis in plants. |
A pigment goes from a ground state to an excited state when a photon boosts one of the pigments electrons to a higher energy electron shell. |
A photosystem is composed of a reaction center complex surrounded by light harvesting complexes. |
Linear electron flow during the light reactions uses both photosystems and produces NADPH, ATP, and Oxygen. |
Light reactions convert solar energy to chemical
Light is a form of electromagnetic energy, the colors we see as visible light include the wavelengths that drive photosynthesis. |
Chlorophyll a is the main pigment of photosynthesis in plants. |
A pigment goes from a ground state to an excited state when a photon boosts one of the pigments electrons to a higher energy electron shell. |
A photosystem is composed of a reaction center complex surrounded by light harvesting complexes. |
Linear electron flow during the light reactions uses both photosystems and produces NADPH, ATP, and Oxygen. |
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The ETC and Chemiosmosis
NADH and FADH2 transfer electrons to the ETC. |
Electrons move down the chain due to the charge of the Oxygen, these electrons eventually are passed to the O2 forming H2O. |
Electron tranfer in the ETC causes protein complexes to H form the mitochondrial matrix to the intermembrane space. |
H diffuses back into the membrane through ATP synthase, driving the phosphorylation of ADP |
About 34% of the energy in a glucose molecule is transferred to ATP during cellular respiration |
Fermentation and Aerobic Respiration
Glycolysis nets 2 ATP by substrate level phosphorylation, this can be done with or without oxygen |
Under conditions without oxygen, either anerobic respiration or fermentation can take place. |
In anerobic, an ETC is present with a final electron acceptor other than oxygen. |
In fermentation, the electrons from NADH are passed to pyruvate or a derivative of pyruvate regenerating the NAD+ required to oxidize more glucose. |
Two common types of fermentation are alcohol fermentation and lactic acid fermentation. |
Fermentation, anerobic respiration, and aerobic respiration all use glycolysis to oxidize glucose, but the differ in their final electron acceptor and whether an ETC is used. |
Calvin Cycle
Calvin cycle occurs in the stroma, it uses electrons from NADPH and energy from ATP. One molecule of G3P exits the cycle per three CO2 molecules fixed. |
C3 plants close their stomata on hot dry days to prevent loss of water. |
Under hot conditions, photorespiration can occur, where Rubisco binds O2 instead of CO2, consuming ATP but releasing CO2. |
C4 plants are adapted to hot environments, they incorporate CO2 into four carbon compounds. |
CAM plants are also adapted to hot climates, they only open their stomata at night. |
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