Chapter 9 Flashcards
Photosynthesis
The process by which light energy is converted into chemical energy in the form of glucose or other carbohydrates, primarily carried out by plants, algae, and some bacteria
Photoautotroph
An organism that uses light energy as its energy source and inorganic carbon (CO2) as its carbon source to synthesize organic molecules
Chloroplast
The organelle found in plant cells and algae where photosynthesis takes place
Thylakoid membrane
An internal system of interconnected flattened sacs within the chloroplast, where the light-dependent reactions of photosynthesis occur
Stroma
The fluid-filled space surrounding the thylakoid within the chloroplast, where the calvin cycle takes place
Light reactions
The first stage of photosynthesis, occurring in the thylakoid membrane, where light energy is absorbed by pigments and converted into chemical energy in the form of ATP and NADPH. water is split, releasing oxygen as a byproduct
Calvin cycle
The second stage of photosynthesis, occurring in the Stroma, where carbon dioxide is fixed and reduced using ATP and NADPH from the light reactions to produce carbohydrates like G3P
Photosynthetic pigment
A molecule that absorbs certain wavelength of light and reflects or transmits others. EX include chlorophyll a, chlorophyll c, and carotenoids
Absorption spectrum
The range of wavelength of light that a particular pigment absorbs
Action spectrum
The rate of photosinthesis plotted as a function of wavelength of light
Excitation
The state of an electron when it absorbs energy and moves to higher energy level
Fluorescence
The emission of light as an excited electron returns to its ground state, releasing energy as heat and light. Occurs in isolated pigment molecules
Resonance Transfer
The transfer of energy from an excited electron in one pigment molecule to an electron in a nearby pigment molecule, causing the second electron to become excited
Electron Transfer
The physical movement of a high0energy electron from one molecule (the electron donor) to another (the electron acceptor)
Electron Acceptor
A molecule that receives a high-energy electron from another molecule, becoming reduced in the process
Electron Donor
A molecule that donates high-energy electron to another molecule, becoming oxidized in the process
Light-Harvesting complex
A collection of pigment molecules (including chlorophylls and carotenoids) bound to proteins in the thylakoid membrane, which capture light energy and transfer it to the reaction center
Reaction center Complex
A protein complex in the thylakoid membrane that contains special pair of chlorophyll a molecules and primary electron acceptor. It is where light energy is converted into chemical energy
Photosystem II
One of the two types of photosystems in the thylakoid membrane. Its reaction center chlorophyll a (P^*)) absorbs light optimally at 680 nm. It is involved in splitting water and initiating linear electron flow
Photosystem I
The other type of photosystem in the thylakoid membrane. Its reaction center chlorophyll a (P700) absorbs light optimally at 700nm. It is involved in reducing NADP+ and NADPH
Linear electron flow
The primary pathway of electron flow in the light-dependant reactions, involving both PSII and PSI and resulting in the production of ATP, NADPH, and oxygen
Chemiosmosis
An energy-coupling mechanism that uses energy stored in the form of an H+ gradient across a membrane to drive cellular work, such as ATP synthesis
ATP synthase
An enzyme complex in the thylakoid membrane that uses the flow of protons (H+) down their electrochemical gradient to catalyze the synthesis of ATP from ADP and inorganic phosphate
Photophosphorylation
The process of generating ATP using the energy of sunlight
Cyclic Electron flow
An alternative pathways of electron flow in the light-dependent reactions that only involves PSI and produces ATP but no NADPH or oxygen
Carbon Fixation
The initial incorporation of inorganic carbon (usually CO2) into an organic compound by an autotrophic organism
Rubisco (ribulose Bisphosphate Carboxylase-oxygenase)
The enzyme in the Calvin cycle that catalyzes the first major step of carbon fixation, the addition of CO2 to RuBP
RuBP (Ribulose bisphosphate)
A five carbon sugar molecule that is regenerated in the Calvin cycle and serves as the initial CO2 acceptor
G3P (glyceradehyde-3-phosphate)
A three0carbon sugar that is the direct product of the Calvin cycle, Can be used to synthesize glucose, starch, cellulose, and other organic molecules
