Marc Barricklow- Honors Biology-8th

Photosynthesis/Cellular Respiration/ Fermentation.

Photosynthesis- Stage 1.

The equation of photosynthesis is Light + H2O + CO2 ----> C6H12O6 + O2 + ATP. There are three stages in photosynthesis. The plant takes in Carbon dioxide and water. The chlorophyll in the chloroplast traps the energy from the light and thylakoids, disk-shaped structures in the chloroplast. when light strikes the thylakoid the energy from the light is transferred to electrons in the chlorophyl, exciting them to a higher energy level. the electrons are then used to power stage two. When the electrons jump, they must be replaced. The plant takes in water molecules and split the hydrogen atoms to fill it. The leftover oxygen is used to make oxygen molecules. This is where the oxygen is produce.

Photosynthesis- Stage 2

The electrons that leave the chlorophyll are used to produce ATP. The electrons travel along the electron transport chains in the process. The movements of the electrons through the electron transport chains provide the energy to make ATP. The ATP is used to power the third stage. There is also a second electron transport chain that provides the energy to make NADPH. NADPH is an electron carrier that provides the electrons needed to make carbon-hydrogen bonds in Stage 3.

Photosynthesis- Stage 3

Stage 3 is called the "Dark" reaction because it doesn't involve light. Carbon Dioxide is used to make compounds which energy is stored. This process is called the Calvin Cycle. First, a molecule of Carbon dioxide is added to a five carbon compound. The resulting 6-carbon splits into 2 three-carbon compounds, Phosphate groups from ATP and electrons from NADPH are added to form three-carbon sugars. One of the sugars is used to make organic compounds for energy to be stored in. The other sugar is used to regenerate the initial five compound, restarting the cycle.

Cellular Respiration

Cellular Respiration is the process cells use to harvest the energy in organic compounds to make ATP. Oxygen makes this process more efficient,Aerobic, but it can be done without out oxygen, Anaerobic. the equation is C6H12O6 + O2 ---> 6CO2 + 6H2O + ATP. There is only three stages to cellular respiration.

Cellular Respiration- Stage 1

Glucose is converted to pyruvate producing ATP and NADPH in small amounts. Glycolysis is the process that breaks down glucose and has 4 steps. In the first step, a series of 3 reactions, phosphate groups from 2 ATP molecules are transferred to a glucose molecule. The next step, 2 reactions, the 6 carbon compound is broken down to 3 carbon compounds, each with a phosphate. 2 NADPH molecules are produced, and 1 more phosphate group is transferred to each 3 carbon compound. In 4 reactions, each 3 carbon compound is converted to a 3 carbon pyruvate, producing 4 ATP molecules in the process.

Cellular Respiration- Stage 2

when oxygen is present, pyruvate produced in glycolysis enters a mitochondrion and is converted to a 2-carbon compound. This produces 1 Carbon dioxide molecule, one NADH molecule, and one 2 carbon acetyl group. (acetyl-coA). This starts the Krebs cycle, a five step process. Step 1: Acetyl-coA combines with a 4 carbon compound, forming a six carbon compound and releasing coenzyme A. Step 2: Carbon dioxide is released from the 6 carbon compound, forming a 5 carbon compound. Electrons are transferred to NAD+, making a molecule of NADH. Step 3: Carbond Dioxide is release from the 5 carbon compound, resulting in a 4 carbon compound.A molecule of ATP is made, and a molecule of NADH is also produced. Step 4: The existing 4 carbon compound is converted to a new 4 carbon compound. Electrons are transferred to an electron acceptor called FAD, making FADH2 (another electron carrier.) Step 5: The 4 carbon compound is converted to the four carbon that started the cycle and another NADH is produced.

Cellular Respiration - Stage 3

The NADH and FADH2 created with the earlier steps pass through an electron transport chain. The energy of the electrons is used to pump hydrogen ions out of the inner mitochondrial compartment- they accumulate in the outer compartment. The hydrogen ions then diffuse back to the inner compartment through a carrier protein that adds a phosphate group to ADH, making ATP. At the end of the ETC hdrogen ions and spent electrons combine with oxygen molecules forming water molecules.

Fermentation- The other way

Fermentation is how some cells make ATP without oxygen. Without the oxygen, the electrons are not transferred from NADH so NAD+ cannot be recycled. Instead fermentation allows the recycling of NAD+ using an organic hydrogen acceptor. There are two types of fermentation, Lactic acid Fermentation and Alcoholic Fermentation.

Lactic acid Fermentation

The pyruvate acid is converted to Lactic acid.

Alcoholic Fermentation

Pyruvate is broken down to ethanol. Carbon dioxide is released through the process. Pyruvate is first converted to a 2 carbon compound, releasing carbon dioxide. Second, electrons are transferred from NADH to the 2 carbon compoundmaking ethanol.

Cellular Respiration and Photosynthesis

Cellular Respiration and Photosynthesis are similar because they both use the products of the other, depending on each other to function. Both of them are ways for the beings to get the energy that they need and depend on glucose. They have many differences.