Chapter 9: Photosynthesis Flashcards
What is photosynthesis?
Basic Definition
Photosynthesis is a chemical conversion that involves the synthesis of glucose.
- Taking CO2 and converting it to Glucose
- Main star: CHLOROPLAST
- We use three items: water, fine capillary roots (plants), sunlight
Photosynthesis Equation
6CO2 + 12H2O+light energy ——> C6H12O6 +6O2 + 6H2O
Name the five photosynthetic organisms
Plants, Alga, Protist, Purple sulfur bacteria, Cyanobacteria
Difference between Autotrophs and Heterotrophs
- Autotrophs (plants) make their own energy (glucose)
- Heterotrophs: consumers and decomposers which need a source of organic molecules to survive
- Humans are heterotrophs
What is light?
- Light is a form of electromagnetic radiation
- Plants absorb light and convert it to sugar/glucose
- Light has different wavelength and quantities of energy
What are electromagnetic waves?
Disturbances of electric and magnetic fields
What is visible light?
- Visible light are the colors, created by waves, that can be viewed by the human eye
- Quantify light by wavelength and energy
- Visible light goes from red to violet
What can you do with visible light? (3)
-Light can be reflected (bouncing back)
-Transmitted (goes through the organism)
-Absorbed (what can be captured)
»»Photosynthesis
What is the function of the chloroplast?
Absorb light.
They are why we see leaves as green/.
What are photons?
Each photon is a discrete unit that contains a fixed amount of energy. That energy is inversely proportional to its wavelength: the shorter the wavelength, the greater the energy of a photon
What is a pigment and what do they do?
-A pigment is something that can absorb light
- When light is absorbed by the pigment, the stability of the atom is disturbed since it is given additional energy
- Makes electrons shift from the orbit they’re supposed to be to different place
- Will be at the excited state. Will try to go back to the stable state.
Ground state/Excited state
The electron goes into the excited state when the photon receives light/energy. The energy state is unstable, so the electron spends less time in that state. As it returns to the ground state, it emits energy. This energy is lost as heat or passed down to a neighboring molecule
How does water travel in the plant? Light?
Xylem allow the water (from the roots) to travel through the plant
->Through adhesion and cohesion forces
Get sunlight through leaf and high surface area
What is the function of the Stroma?
Remove carbon from CO2 and then mix it with oxygen and hydrogen to make a simple carbohydrate molecule (LIGHT INDEPENDENT REACTION)
Light reaction vs. Calvin-Benson cycle
Light reaction
- Uses light energy, water, NADP+, ADP
- Produces ATP and NADPH + (H+)
The Calvin-Benson Cycle
- Reduction reaction since carbon is gaining hydrogen
- Uses ATP, NADPH + (H+), and CO2
- Produce sugars (phosphoglyceraldehyde)
- **CO2 fixation
Where does photosynthesis occur?
Chloroplasts
- Contains grana, which are made up of thylakoids (folded membrane)which contain chlorophyll
- Inside the chloroplast is a fluid, stroma
Pigments
- Capture light and use it to provide energy to carry out photosynthesis
- located in the Thylakoid
What is a photosystem?
A bunch of molecules working together to make light
PHOTOSYSTEM II (STEPS)
○ Light is shining at the photosystem
○ A molecule of the photosystem is receiving and absorbing the light
○ Molecule goes to the excited state
§ It is going to take the energy and dump it to the next molecule in its vicinity
§ Second molecule received energy and transfers it to the next and so on.
□ Eventually it gets to the reaction center
□ The reaction center (P680)will keep the energy and lose/transfer an electron
□ **every molecule is transferring energy except for the reaction center
- The electron lost from the reaction center goes to the electron transport chain and generates ATP by chemiosmosis
- In order to re-stabilize the reaction center, an H20 is broken down. The O2 is released into the environment and the hydrogens (pumped from thylakoid lumen to stroma) are used to power ATP synthase (phosphorylation) in the ETC
PHOTOSYSTEM I (STEPS)
○ Transfer of molecules to the reaction center
§ Gets electrons from the ETC
§ Electrons are passed to Fd
§ NADP reductase catalyzes the transfer of electrons to NADP+ (becomes NADPH)
§ Acyclic: one electron is being transferred form a photosystem to another
PQ
PLASTOQUINONE
Electron Transport Chain
Cyt
CYTOCHROME
Electron Transport Chain
PC
PLASTOCYANIN
Electron Transport Chain
Fd
FERRODOXIN
Electron Transport Chain
