Metabolism Flashcards
Photosynthesis is…
The process by which plants use sunlight to convert carbon dioxide into glucose.
what does the thylakoid contain? How does it help photosynthesis?
Contains pigments that absorb light energy —> light energy is used to power photosynthesis
What does the stroma do? One sentence.
Uses the products of the thylakoid’s reactions to FINISH photosynthesis and create glucose.
Light energy ______ water.
Oxidizes
What happens in the first stage of photosynthesis? Three steps.
- Light energy oxidizes water.
- Electrons are excited by light and make ATP.
- Electrons reduce NADP+ into NADPH.
What happens in the second stage of photosynthesis? One step.
The NADPH and ATP add CO2 to carbon molecules to create glucose.
What is a pigment?
A substance that absorbs light.
What are OTHER names for the first and second stages of photosynthesis?
- Light dependent reactions.
- Light independent reactions.
The _______ pigments will travel the farthest on chromatography paper, because ________.
Most polar, because polar molecules are attracted to the water.
A stack of thylakoids is called a…
Granum.
Where do stages 1 and 2 of photosynthesis occur?
Stage 1 - thylakoid. Stage 2 - stroma.
Photosystems II and I are light __________
Dependent reactions.
Summarize photosystem II (P680) in three points.
1 - Photolysis, light energy splits oxygen into H+ and O2, releasing electrons.
2 - light energy excites electrons held in the reaction centre
3 - electrons move down electron transport chain, producing ATP
Summarize photosystem I (P700) in three steps.
1 - electrons from pII end up in reaction centre of pi. Electrons are excited by light energy once again.
2 - excited electrons are captured by another ETC. reduce NADP+ to NADPH
3- products (ATP and NADPH) are transferred to stroma for Calvin Cycle.
Describe the three stages of the Calvin Cycle.
1 - RuBP + 3 CO2. Ends up as 6 PGA. Catalyzed by RuBisCo.
2 - 6 PGA + ATP + NADPH, ends up as 6 PGAL/GA3P). Building block for glucose.
3 - 1 PGAL leaves to make 1/2 glucose. Rest regenerates RuBP.
What happens during photorespiration?
RuBisCo incorporates O2 into RuBP instead of CO2. Wasteful, no useful product.
What two factors determine whether RuBisCo will use O2 or CO2?
Low temp, high CO2 concentration = Calvin Cycle
High temp, low CO2 concentration = photorespiration
Describe how each C3, C4, and CAM plants process O2/CO2.
C3: use RuBisCo to convert CO2 into PGA. Sensitive to photorespiration.
C4: CO2 physically separated from oxygen to improve CO2 bonding (leaf tissue layers).
CAM: carbon dioxide reserves creates to improve CO2 consisting to RuBisco.
How many ATP are created in Aerobic Respiration vs Anaerobic?
38 ATP in aerobic respiration. 2 ATP in anaerobic, plus a toxic byproduct (lactic acid in animals, alcohol in yeast)
Now the four stage of aerobic respiration.
Glycolysis, pyruvate oxidation, citric acid/Krebs cycle, electron transport chain
Where does glycolysis occur? Is it aerobic or anaerobic?
Cytosol, anaerobic.
Where does pyruvate oxidation occur? Is it aerobic or anaerobic?
Mitochondrial matrix, aerobic.
Where does the Krebs cycle occur? Is it aerobic or anaerobic?
Mitochondrial matrix, aerobic.
Where does the ETC occur? Is it aerobic or anaerobic?
Inner membrane of mitochondria, aerobic.
What are the inputs/outputs of glycolysis?
Inputs: 1 glucose, 2 ATP
Outputs: 2 pyruvate, 4 ATP, 2 NADH
What else can be used instead of glucose during glycolysis? How does it work?
Fats - remove glycerol from fatty acids (using lipases), glycerol becomes PGAL
Proteins - proteases break protein into amino acids. deaminases remove amino group, rearranged into pyruvate/acetyl CoA
What are the inputs/outputs of pyruvate oxidation?
Inputs: 2 pyruvate
Outputs: 2 acetyl CoA (byproduct, 2 CO2, 2 NADH)
What are the inputs/outputs of the citric acid/Krebs cycle?
Inputs: 1 acetyl CoA
Outputs: 2 CO2, 3 NADH, 1 FADH2, 1 ATP
Describe how the electron transport chain functions.
NADH & FADH2 deliver electrons and drive ATP synthesis. Energy stored from electron transfer through the chain forms a proton gradient, energy stored in gradient is used to make ATP.
What is the role of oxygen in the ETC?
Oxygen “mops up” excess electrons and protons to make water. If oxygen is not present, ETC will stop and ATP production will also cease.
