Metabolic Processes Photosynthesis Flashcards
Two Stages of Photosynthesis
Light dependent and light independent
Light Dependent reactions
- absorption of photons of light
- light needs to be present
Light independent reactions
- Calvin cycle
- need for Calvin cycle to happen
- need ATP and NADPH (can be In the dark)
- light needs to be absorbed
Photosynthetic Organisms
Organisms that carry our photosynthesis:
- plants
- algae
- some protists
- Cyanobacteria
What organisms are Eukaryotes Autotrophs
Algae, photosynthetic protists and plants
Eukaryotic Autotrophs
- They have chloroplasts as discrete organelles
- Green colour due to chlorophyll
- In plants, leaves -primary organs for photosynthesis
Chloroplasts
Photosynthetic “powerhouse”
Both LD reactions and Calvin cycle take place in here
Chloroplast 3 membrane structure
Outer, inner and thylakoid membrane
What plants must obtain for photosynthesis to take place?
Carbon dioxide
Water
Light energy
Capturing light energy
The ability to trap light energy and convert to chemical energy requires a sophisticated photochemical apparatus
Primary electron acceptor
Molecule capable of accepting electrons and becoming reduced during photosynthesis
Chlorophyll
major photosynthetic pigments in plants, green algae, and cyanobacteria
2 types of chlorophyll
Chlorophyll a and chlorophyll b
Carotenoids
second major group of photosynthetic pigments
Antenna Complex
captures light energy and transfers it to a chlorophyll a molecule and the primary electron acceptor in the reaction centre
Absorption spectrum
measures the magnitude of absorption of light of a pigment
Action spectrum
plots the effectiveness of light of various wavelengths in driving photosynthesis
Proteins =
Photosystems
Photosystem I (PSI)
absorb light optimally at wavelengths 700 nm (P700 molecules)
Photosystem II (PSII)
absorb light optimally at wavelengths 680nm (P680 molecules)
Cuticle
protecting film covering the epidermis of leaves
Upper epidermis
top of leaf, single layer of cells directly below cuticle, protects leaf, providing water loss and providing an extra layer between out/in of leaf
palisade mesophyll
absorb light for photosynthesis to take place. Consists of chloroplasts with chlorophyll
Spongy mesophyll
leaf tissue consisting of loosely arranged chloroplasts bearing cells, located on lower side of leaf
lower epidermis
single layer of cells on lower surface of leaf. contains stromata and guard cells. Stroma allows exchange for C)2 and O2 and transpiration
stroma
tiny openings or pores in tissue that allows for gas exchange. Mostly found in leaves sometimes stems
air space
irregularly shaped cells loosely packed with air spaces. storage place for products of photosynthesis
Xylem veins
transports water + minerals from roots to leaves (upper side of veins)
Phloem veins
transports carbohydrates made by photosynthesis in leaves and rest of plant (lower side)
Proton Motive Force
occurs when the cell membrane becomes energized due to electron transport reactions by the electron carriers embedded in it.
Proton Motive Force 3 mechanisms
- reduction and oxidation of plastoquinon
- addition of two protons for each water molecule spilt in thee lumen
- removal of one proton for each NADP+ reduced in the stroma
Role of light energy
drives photosynthetic electron transport chain
gives energy H20
PSI has the same function as PSII
Types of ETC in photosynthesis
- linear (makes ATP, NADPH) including P680 and NADP+ reductase
- clitic, electrons kept in P700
Calvin cycle three phrases
- carbon fixation
- reduction reaction
- regeneration of ribulose 1, 5-biphosphate (RuBP)
Most important enzyme in calvin cycle
Rubisco
C3 plants conditions
On hot, dry days, these plants close stomata to prevent water loss and gas exchange
C4 plants conditions
Tropical pants, and several temperate crop species. (warmer climates)
Photorespiration
the catalysis of O2 instead of CO2 by rubisco into RuBP, which slows the Calvin cycle, consumes ATP, and results in a release in a release of carbon
C4 cycle
an alternative form of carbon fixation that some plants use., particularly in hot water, increases the concentration of CO2 available for the Calvin cycle reactions
CAM plants conditions
hot and dry during the day and cool at night
CAM metabolism
used mostly by succulent plants, which the Calvin cycle and the C4 cycle are separated in time for better efficiently of CO2 fixation
