Energy in living things all begins in the sun. Photosynthesis transforms the sun's energy into a chemical form by storing it in sugars. These sugars can be broken down in cellular respiration so that the energy stored within their bonds can be stored in the bonds of ATP and used for life functions when those bonds are broken.
Adenosine Triphosphate (ATP)
is the energy currency that cells "spend" to do work. The energy is stored in the bonds between the phosphates of ATP. When the last phosphate is removed, energy is released that the cell can spend. Since the molecule loses a phosphate and is left with two, it is now called Adenosine Diphosphate (ADP.) An enzyme called ATPsynthase can then add a phosphate to the ADP, storing energy, and creating ATP. |
ATP The Energy "Currency"
The Products of Photosynthesis are the Reactants of Respiration
Photosynthesis allows plants to capture energy from the sun and store it as chemical energy in carbon compounds such as simple sugars like glucose. This chemial energy is later broken down and used by cells. Photosynthesis has two parts that occur along side each other, the light-dependent reactions and light independent reactions.
Light
6CO2 + 6H2O -------------> C6H12O6 + 6O2
6CO2 + 6H2O -------------> C6H12O6 + 6O2
Light Dependent Reactions are the series of chemical reactions that can only occur in the presence of light.
Light
6 CO2 + 6 H2O ------> C6H12O6 + 6 O2 In the Thylakoids (Grana)
- Chlorophyl absorbs sunlight, exciting electrons. - Light energy "splits" water (H2O) molecules - The oxygen from water leaves as oxygen (O2) - The hydrogen from water is used to store the excited electrons in ATP and NADPH which, power the Calvin Cycle |
Light Independent Reactions (aka Calvin Cycle aka dark reactions) are the series of reactions that use the products of the light dependent reactions and carbon dioxide, so they can occur with or without sunlight. (Animation)
Photosynthesis occurs in the chloroplasts. Chloroplasts are green because of the pigment chlorophyll which, reflects green light and absorbs other colors.
Light Dependent Reactions take place in the thylakoids. A stack of thylakoids is called a granum. Multiple stacks are called grana. Light Independent Reactions (the Calvin Cycle) take place in the stroma, the fluid space surrounding the grana, inside a chloroplast. Think of a bag, inside a bag, full of tiny pancakes surrounded by water. The bags are the two membranes, the pancakes are thylakoids, the water is the stroma |
CrashCourse Amoeba Sisters <--------------- watch these videos for extra help
Gas Exchange in Plants
In order to obtain carbon dioxide from the atmosphere, plants have small openings called stomata on their leaves. Stomata allow carbon dioxide to enter but also can let water out.
Guard cells around the stomata spend energy to close the opening, preventing water loss.
Most plants leave their stomata open during the day to let in carbon dioxide since this is when light is present, and used for photosynthesis. However, if it becomes too hot, the plant can prevent waterless by closing the stomata. Since their is no light at night, most plants keep their stomata closed to prevent water loss.
Plants in different environments have different adaptations based on the amount of water and light they receive.
The Products of Photosynthesis are the Reactants of Respiration
Aerobic Cellular Respiration uses oxygen in the chemical breakdown of sugar to release the energy stored in its bonds as ATP which, can be used in cell processe
C6H12O6 + 6O2 -------------> 6CO2 + 6H2O + ATP energy
The Krebs Cycle and Electron Transport Chain both require OXYGEN and take place in the MITOCHONDRIA.
The Krebs Cycle (Animation)
The two pyruvate molecules made during glyolysis are further broken down inside the matrix of the mitochondria, making high energy molecules and 2 ATP molecules. Carbon Dioxide (CO2) is released as a by-product.
The two pyruvate molecules made during glyolysis are further broken down inside the matrix of the mitochondria, making high energy molecules and 2 ATP molecules. Carbon Dioxide (CO2) is released as a by-product.
Electron Transport Chain (Animation) The high energy molecules transport their electrons down a chain in the inner membrane of the mitochondria. Oxygen (O2) "accepts" the electrons (Hydrogen), creating water (H2O) and 32 ATP molecules.
When oxygen is present Aerobic Respiration produces 38 ATP molecules total from one glucose molecule.
1. Glycolysis produces 2 ATP
2. Krebs Cycle produces 2 ATP
3. Electron Tensport Chain produces 34 ATP
When oxygen is NOT present Anaerobic Respiration produces 2 ATP molecules total from one glucose molecule. After glycolysis, fermentation begins producing lactic acid or alcohol.
1. Glycolysis produces 2 ATP
2. Krebs Cycle produces 2 ATP
3. Electron Tensport Chain produces 34 ATP
When oxygen is NOT present Anaerobic Respiration produces 2 ATP molecules total from one glucose molecule. After glycolysis, fermentation begins producing lactic acid or alcohol.
CrashCourse Amoeba Sisters <--------------- watch these videos for extra help
Anaerobic Cellular Respiration When oxygen is not present, Glycolysis still occurs by recycling NADH (NAD+) and producing 2 molecules of ATP, but the Krebs Cycle and Electron Transport Chain never begin. This is also called FERMENTATION
The Products of Photosynthesis are the Reactants of Respiration
Quiz yourself with this Photosynthesis and Cellular Respiration Kahoot!
Your Foldable Note Taker (Instructions) is a great review tool to compare the processes of photosynthesis and respiration