Chapter 6: Part 2 Photosynthesis Flashcards
All life forms require what?
They require an energy source and a carbon source
What are the two types of carbon source?
- Autotroph
2. Heterotroph
Autotroph
An organism can make its own food from inorganic substances and it fixes carbon CO2
Heterotroph
An organism that can’t produce its own food requires food from organic carbon (Consumers in the food chain)
What are the two types of energy source?
- Phototroph
2. Chemotroph
Phototroph
An organism that captures energy from sun-light
Chemotroph
An organism that uses either an organic or inorganic source of energy
Photoautotroph
Organisms that can make their own energy using light and carbon dioxide via the process of photosynthesis
Chemoautotroph
is an organism that produces its cellular energy, usually in the form of ATP, directly from the environment using a chemical source. It uses carbon dioxide
Chemoheterotroph
are unable to utilize carbon dioxide to form their own organic compounds. Their carbon source is rather derived from sulfur, carbohydrates, lipids, and proteins.
Photoheterotroph
an organism that makes energy from light but uses organic materials for its carbon source instead of inorganic carbon dioxide, which is used by photoautotrophs.
Photosynthesis
Is the process of capturing energy from sunlight
Oxygenic Photosynthesis
Energy from light drives the process of light energy transfers electrons from water/H2O (oxidize) to carbon dioxide/CO2 (reduced) to produce carbohydrates
What are the similarities between photosynthesis and cellular respiration?
- Redox reactions
- Electron transport
- Chemiosmosis
Cyanobacteria
Cyanobacteria are the closest relatives of chloroplasts and do oxygenic photosynthesis
What are the two pathways(stages) for photosynthesis?
- Light-dependent reactions (occurs in the thylakoid membrane)
- Light-independent reactions (aka Calvin cycle and occur in the stroma of the chloroplasts membrane)
Light-dependent reactions
Are enzymes that only work in light and convert light energy into chemical energy (in ATP and the reduced electron carrier NADPH)
Light-independent reactions
It uses the ATP and NADPH from the light-dependent reaction along with CO2 to produce carbohydrates
Light
Is a form of electromagnetic radiation, which travels as a wave but also behaves as particles
Photon
A light particle (that can excite an electron when a molecule absorbs it)
Pigments
Molecules that absorb light within the visible spectrum
Absorption Spectrum
Records the wavelengths over which a pigment absorbs light
What are the two groups of pigments in photosynthetic organisms?
- Chlorophyll A and B pigment
2. Carotenoid pigment
Chlorophyll Pigment structure and purpose
Chlorophyll molecules have complex ring structures that absorbs light and drive the light reactions in photosynthesis
Carotenoid Pigments
Are accessory pigments that absorbs wavelengths of light between the red and blue wavelengths, and transfer a portion of that energy to the chlorophylls
Photosystem
large complexes of proteins and pigments (light-absorbing molecules) that are optimized to harvest light, play a key role in the light reactions.
Photosystem 2
One of two light-capturing units in a chloroplast’s thylakoid membrane; it has two molecules of 680nm chlorophyll A at its reaction center, makes ATP and uses electrons from light
Photosystem 1
P700, makes NADPH and does not take place first
What are the 2 photosystems?
- Photosystem 1 (PSI)
2. Photosystem 2 (PSII)
Calvin cycle is composed of what?
It is composed of three distinct processes, each step is catalyzed by a specific enzyme
What are the three processes of the Calvin cycle?
- Carbon fixation
- Reduction and sugar productions
- Regeneration of RuBP
Carbon Fixation
A CO2 molecule combines with a five-carbon acceptor molecule, ribulose-1,5-bisphosphate (RuBP). This results in 6C molecule that is unstable and breaks down into two 3C molecules
- Reduction and Sugar Production
is the second stage where ATP and NADPH are used to convert the 3-PGA molecules into molecules of a three-carbon sugar, glyceraldehyde-3-phosphate (G3P). This stage gets its name because NADPH donates electrons to, or reduces, a three-carbon intermediate to make G3P.
Regeneration of RuBP
Some G3P molecules go to make glucose, while others must be recycled to regenerate the RuBP acceptor.
RuBP Acceptor
Is a ribulose-1,5-bisphosphate
Rubisco
Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate).
How many ATP can be made in the Calvin cycle?
54 ATP
What can influence the efficiency and the way the Calvin cycle work?
Light intensity
Temperature
Water availability
Photorespiration
is a wasteful pathway that occurs when the Calvin cycle enzyme rubisco acts on oxygen rather than carbon dioxide.
C3 Plants
A “normal” plant—one that doesn’t have photosynthetic adaptations to reduce photorespiration
C4 Plants
A plant that physically separates the light-dependent reactions and the Calvin cycle
Crassulacean Acid Metabolism (CAM)
A plant that uses a pathway to minimize photorespiration by separating the process of light-dependent reactions and the use of CO2 at different times
Stomata
the small openings (pores) on the undersides of most leaves through which oxygen and carbon dioxide can move
Chemosynthesis
Where some organisms use chemical energy rather than light energy to fix carbon
Chlorophyll A
Is the primary pigment of photosynthesis and absorbs orange-red and blue-violet light
Chlorophyll B
Is the accessory pigment of photosynthesis and is not necessary for photosynthesis to occur and absorbs blue light
What is Chlorophyll A’s main job?
Chlorophyll A’s central role is to be a primary electron donor in the electron transport chain.
What is Chlorophyll B’s main job?
Chlorophyll B’s central role is to expand the absorption spectrum of organisms
Cyclic Electron Transport
It uses only photosystem I and produces only ATP
Antenna Complex in Photosynthesis
is a collection of pigments and proteins that capture and funnel energy from light.
What is the role of Rubisco?
The role is to catalyze the bonding of CO2 to an unstable six-carbon compound. It also uses O2 and CO2 as substrates
Carbon dioxide is “fixed” by bonding to what?
ribulose 1,5-bisphosphate, RuBP
Chloroplast
Is n organelle with two membranes, the inner membrane being folded into stacks of thylakoids, forming the inner membrane space, the lumen, and the stroma