Bio Notebook Essay, Research Paper
Defn: “To make with light”
CO2, H2O, Sunlight, chlorophyll
Food (C6H12O6 = glucose) and O2
Photosynthesis is actually a series of two reactions.
Light reactions (require sunlight)
chlorophyll uses sunlight to split water and form oxygen and chemical energy.
Dark reactions (don t require light)
use chemical energy from light reaction to convert carbon dioxide into glucose.
Where does photosynthesis take place?
Structure of a Chloroplast
chlorophyll absorbs red, orange, blue and violet, and use the energy of light to do work.
The light reactions
occur on the surface of the thylakoid membrane.
The chemistry of light reactions
occurs in the stroma
also called the, “Calvin-Benson Cycle”
The energy to do all this work comes from the light reactions.
Chemistry of dark reactions
Overall reaction combining separate light and dark reaction equations.
Definition: Breaking down food (glucose) to get energy.
Every step of this pathway is controlled by enzymes.
Overall Chemical Equation:
Glucose is broken down and energy is formed in a three step process.
Glucose broken down to form 2 three carbon molecules
Kreb s Cycle
three carbon molecules are broken down to 3 carbon dioxide molecules
protons generated in two previous steps are with oxygen to make water and ATP.
Glycolysis (nine step process)
Takes place in the cytoplasm of a cell.
Doesn t require oxygen.
2 ATP are needed to begin this reaction, but 4 ATP are made, therefore 2 ATP is the net yield.
Glucose (6-carbon) is broken down into 2 pyruvic acid molecules (3-carbon).
If oxygen levels are still low, there are two options:
In yeast and bacteria:
If oxygen is available then pyruvic acid enters the Kreb s Cycle.
Kreb s Cycle
Takes place in the mitochondria.
No final end product, just continuous series of reactions.
Pyruvic acid is broken down into a carbon dioxide and a 2 carbon acetyl molecule.
Acetyl molecule is broken down into 2 carbon dioxides, 1-ATP, 3-NADH and 1-FADH2.
Hydrogen protons produced from Kreb s Cycle are carried to the electron transport system by NAD and FAD molecules.
Total ATP production from first 2 steps of respiration is now 4 for one glucose molecule.
Electron Transport System
Hydrogen s are grabbed by a molecule called Nicotinamide Adenine Dinucleotide (NAD), and carried to the proteins of the electron transport system.
Hydrogen atoms are striped of their electrons and the electrons are sent through a series of reactions.
As electron is passed from one molecule to another in the electron transport chain, energy is generated.
17 times more productive than anaerobic respiration.