Chapter 5: Phtosynthesis & Cellular Respiration Flashcards
- Photoexcitation
Light energy bounces across pigments until it reaches the reaction center
-When the e- is at the reaction it becomes excited and moves up an energy level, where it is picked up by an electron acceptor
- ETS (Electron Transport System)
-The excited electron is transferred between e-carrying molecules
-With each transfer, energy is released to pump H+ ions inside the lumen
- PSI (Photolysis)
-The reaction center is now missing an electron
-To replace the missing electron, H2O molecules are broken down/split into 4H, 4e-, & O2
-The oxygen is released into the atmosphere the electron replaces the missing one and the hydrogen ions continue to build up inside the thylakoid membrane along with other hydrogen ions generated to create a “hydrogen ion gradient”
- End of the Electron Transport Chain
-A NADP+ molecule comes and takes 2 energized electrons and one H+ to form NADPH
- ATP Synthase (Chemiosmosis)
-H+ ions move down ATP synthase following the concentration gradient (created by the difference of hydrogen concentrations)
-Their energy is used to convert ADP–>ATP to fuel cellular activities.
3 Stages of Calvin Cycle
-Carbon fixation
-Reduction
-Regeneration
Calvin Cycle
-Converts CO2 from the atmosphere into carbohydrates (or sugars) which the plant needs to power cellular activities and build new plant structures.
-Occurs within stroma
- Carbon Fixation
A CO2 molecule combines with a five-carbon molecule (RuBP).
-This step makes an unstable 6-carbon compound that splits into 2 molecules of a 3-carbon compound (3-PGA)
-This reaction is catalyzed by an enzyme called Rubisco
- Carbon Reduction
ATP & NADPH
-In the second stage, ATP and NADPH which supply the needed electrons and energy for CO2 reduction, are used to convert the 3-PGA molecules into molecules of a 3-carbon sugar (G3P) through a series of reactions
- One of the G3P molecules is set aside as a building block for glucose, but the majority of G3P molecules move forward into the third phase of the Cycle.
- -It is named G3P because NADPH donates electrons to, or reduces a 3-carbon intermediate to make G3P.
- Regeneration
-Requires ATP
-Regenerate acceptor
-Some G3P molecules go to make glucose, while others must be recycled to regenerate the RuBP acceptor, using ATP.
-Regeneration requires ATP and involves a complex network of reactions.
-To form a glucose molecule, the cycle has to turn 6 times because each turn only adds one carbon atom from the incoming CO2
Aerobic Cellular Respiration
-glucose reacts with oxygen, forming ATP that can be used by the cell. Carbon dioxide and water are created as byproducts.
-cellular respiration, glucose and oxygen react to form ATP.
Steps of Cellular Respiration (In Order)
- Glycolysis
- Krebs Cycle Prepraration
- Krebs Cycle (Citric Acid Cycle)
- Eelectron Transport System & Chemiosmosis
Glycolysis ATP: 2 net gain
-Occurs in the cytoplasm outside of the mitochondria.
-Enzymes break down glucose into 2 molecules of pyruvate
-During this process, 2ATP is produced and 2NADH is released to be used in a later step of cellular respiration
Investment Phase: 2NAD, 2ADP
Return Phase: 2NAD 2NADH, 4ADP, 4ATP
- Preparatory Reaction (Krebs Cycle Preparation) ATP: 2 net gain
-The pyruvates of glycolysis move into the mitochondria where they are oxidized and then converted to Acetyl CoA (coenzyme A)
-During this conversion process, more NADH is produced, and CO2 is released
- Krebs Cycle (Citric Acid Cycle)
ATP: 2 net gain
-The remaining carbon from the initial glucose is oxidized releasing CO2, NADH, FADH2, and 2 ATP molecules.
-Transforms the energy from glucose into the reducing power of NADH AND FADH2.
-NADH and FADH2 bring excited electrons (reducing power) to the ETS
-Oxaloacetate is the starting and ending compound.
Net gain: 1 pyruvate, 3 NADH, 1 glucose 6 NADH 2 FADH2
