4.4.notebook
October 03, 2013
Glycolysis occurs in all cells and is an ongoing process.
­Occurs in the cytoplasm
­Anaerobic
­When oxygen is available the products of glycolysis will be used in cellular respiration.
Process:
1. 2 ATP molecules energize the glucose molecule.
2. Glucose molecule is split into 2 three­carbon molecules.
3. Energized electrons from the three­carbon molecules are transferred to NAD+, which forms NADH (just another electron carrier).
4. A series of reactions converts the three­carbon molecules to PYRUVATE, which enters cellular respiration.
5. 4 ATP molecules are made.
Do the math: If 2 ATP molecules are needed to start glycolysis and only 4 are produced, how many are actually gained?
The pyruvate and the NADH are used for cellular respiration, if oxygen is present.
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4.4.notebook
October 03, 2013
Krebs Cycle
1. Pyruvate is broken down
­Split into a two­carbon molecule and a molecule of CO2 is released.
­Electrons are transferred from the two­carbon molecule to NAD+ to make NADH
­The NADH moves to the electron transport chain.
2. Coenzyme A
­An intermediate molecule is formed from Coenzyme A and the two­carbon molecules from step 1.
3. Citric Acid is formed
­ A six­ carbon molecule called Citric Acid is formed.
4. Citric acid is broken down
­Creates a five­carbon molecule
­ This produces NADH and moves out of the Krebs cycle
­A molecule of CO2 is given off
5. Five­carbon molecule is broken down
­A four­carbon molecule is formed
­NADH and a molecule of ATP are produced
­NADH leaves the Krebs cycle ­A molecule of CO2 is given off.
6. Four­carbon molecule is rearranged
­Molecules of NADH and FADH2 (another electron carrier) are made and leave the Krebs Cycle.
Products from one molecule of Pyruvate
­3 molecules of CO2
­1 molecule of ATP
­4 molecules of NADH sent to the electron transport chain
­1 molecule of FADH2 sent to the electron transport chain
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October 03, 2013
Electron Transport Chain
­Occurs in the inner membrane of the mitochondria
­Made up of proteins
­Use energy supplied by NADH and FADH2
1. Electrons removed
­Take high­energy electrons from NADH and FADH
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­Need to use 2 molecules of NADH and 1 molecule of FADH2
2. Hydrogen Ions Transported
­Proteins use energy from the electrons to pump hydrogen ions against the concentration gradient. (just
like photosynthesis)
­Causes a build up of hydrogen ions inside the inner membrane.
3. ATP produced
­Hydrogen ions diffuse through a protein channel which is part of ATP synthase
­ATP synthase adds phosphate groups to ADP to make ATP
­For every pair of electrons, 3 ATP are produced.
4. Water formed
­Oxygen enters cellular respiration
­Picks up electrons and hydrogen ions to become water
­Water is given off
Products of Cellular Respiration (including glycolysis)
­CO2
­H2O
­Up to 38 molecules of ATP for every glucose molecule
­2 from glycolysis, 2 from the Krebs cycle and up to 34 from electron transport chain
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October 03, 2013
Organelle for Chloroplast
Process
Mitochondria
Reactants
C6H12O6 and CO2 and H2O
O2
Electron Transport Chain
Proteins within thylakoid membrane
Proteins within inner mitochondrial membrane
Cycle of Chemical Reaction
Calvin Cycle in stroma of chloroplasts builds sugar molecules.
Krebs cycle in matrix breaks down carbon­based molecules.
Products
C6H12O6 and O2
CO2 and H2O
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