Metabolism Flashcards
What are mitochondria?
Mitochondria are vital organelles specialized in the production of large quantities of ATP and are only found in eukaryotic (animal) cells.
What is the structure of mitochondria?
Mitochondria have an outer membrane and an inner matrix where various metabolic processes occur, including glycolysis outside the cell and pyruvate oxidation, Krebs cycle, and oxidative phosphorylation inside the matrix.
What is the fluid mosaic model of the cell membrane?
The fluid mosaic model describes the structure of the cell membrane as a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrate chains, allowing selective permeability and cell signaling.
What are the functions of the cell membrane?
The cell membrane functions in selective permeability, signal transduction, cell recognition, and providing structural support.
What is the difference between polar and non-polar molecules?
Polar molecules have an uneven distribution of charges and are typically hydrophilic, while non-polar molecules have an even distribution of charges and are typically hydrophobic.
What is passive transport?
Passive transport is the movement of molecules across the membrane without energy input, moving down their concentration gradient.
What is active transport?
Active transport is the movement of molecules across the membrane with energy input (ATP), moving against their concentration gradient.
What is glycolysis?
Glycolysis is the first step of cellular respiration occurring in the cytoplasm, converting glucose into 2 pyruvates, 2 ATP, and 2 NADH without requiring oxygen.
What are the stages of aerobic cellular respiration?
The four stages of aerobic cellular respiration are glycolysis, pyruvate oxidation, Krebs cycle, and the electron transport chain (ETC).
What is the role of NADH and FADH2 in cellular respiration?
NADH and FADH2 act as electron carriers, delivering high-energy electrons to the electron transport chain, contributing to ATP production.
What is fermentation?
Fermentation is an anaerobic process that allows organisms to produce energy without oxygen, resulting in products like ethanol or lactic acid.
What are the light-dependent reactions of photosynthesis?
Light-dependent reactions occur in the thylakoid membrane of chloroplasts, converting light energy into ATP and NADPH while releasing oxygen.
What are the light-independent reactions (Calvin cycle)?
The Calvin cycle takes place in the stroma of chloroplasts, using ATP and NADPH to convert CO2 into glucose.
What is the electromagnetic spectrum’s role in photosynthesis?
The electromagnetic spectrum provides light energy for photosynthesis, with chlorophyll absorbing primarily red and blue wavelengths.
What is the purpose of the chemiosmotic model in ATP synthesis?
The chemiosmotic model explains ATP synthesis via ATP synthase, where a proton gradient created by the electron transport chain drives the conversion of ADP to ATP.
What is the role of electron carriers in the membrane?
Electron carriers cause a negative charge in the membrane.
What happens during photolysis?
Water molecules are split to produce electrons and oxygen, replenishing lost electrons in the ETC.
2H2O → 4e- + 4H+ + O2
How does water reach the thylakoid lumen?
Water is taken from the roots through the vascular bundles (Xylem) into the thylakoid lumen.
What is the significance of water for plants?
Water is essential for replenishing electrons in PSII; without it, the reaction cannot occur.
What occurs in the electron transport chain (ETC)?
High-energy electrons travel through the ETC, releasing energy as they move between protein complexes.
What is the role of plastoquinone (PQ) in the ETC?
PQ accepts excited electrons from PSII and takes a H+ ion from the stroma to drop it into the thylakoid lumen.
What happens to electrons after they are passed to plastocyanin (PC)?
Electrons go from PC to PSI.
What is the function of NADP synthase at PSI?
NADP is converted to NADPH using low-energy electrons and a hydrogen from the stroma.
How is ATP produced in the light reactions?
H+ ions diffuse through ATP synthase, facilitating the conversion of ADP and Pi into ATP.
What are the inputs and outputs of the Calvin Cycle?
Inputs: 6CO2, 18 ATP, 12 NADPH; Outputs: 1 glucose (C6H12O6), 18 ADP, 12 NADP+.
What occurs during carbon fixation in the Calvin Cycle?
CO2 binds with RuBP, forming an unstable 6C compound that splits into 2 PGA.
What happens in the reduction phase of the Calvin Cycle?
3-PGA is converted into G3P using ATP and NADPH from light-dependent reactions.
How is RuBP regenerated in the Calvin Cycle?
5 G3P are recycled to regenerate RuBP using ATP.
What are the features of non-cyclic photophosphorylation?
Involves PSII and PSI, linear electron pathway, produces ATP and NADPH, and includes water splitting.
What are the features of cyclic photophosphorylation?
Involves PSI only, circular electron pathway, produces ATP but not NADPH, and does not involve water splitting.
What is the chemiosmotic model of ATP production?
It explains how the flow of protons across a membrane drives ATP synthesis during light reactions.
What is the role and location of NADPH?
NADPH supplies high-energy electrons for reducing 3-PGA to G3P in the Calvin cycle, located in the stroma.
What factors affect NADPH?
Light intensity, electron transport efficiency, water availability, and Calvin cycle rate.
What is the role and location of RuBP?
RuBP accepts CO₂ in the Calvin cycle and forms 3-PGA with RuBisCO, located in the stroma.
What factors affect RuBP?
ATP/NADPH availability, RuBisCO activity, CO₂ levels, and temperature.
How do C3 and C4 plants differ?
C3 plants use 3-phosphoglycerate for carbon fixation, while C4 plants use oxaloacetate, enhancing efficiency in hot, arid conditions.
What are key characteristics of C3 plants?
Common in cooler climates, directly take CO₂ from the atmosphere, less efficient under stress.
What are key characteristics of C4 plants?
More efficient in water use, favored in high temperature and light conditions, use an additional step before the Calvin cycle.
What is photorespiration?
Occurs when CO2 levels are low, leading Rubisco to combine O2 with RuBP instead of CO2, producing less PGA and a toxic molecule.
