Photosynthesis and Cellular Respiration Cellular Energy Photosynthesis and Cellular Respiration

Photosynthesis Basic reaction: Rate varies with 6 CO2 + 12 H2O + light energy, chlorophyll, enzymes → C6H12O6 + 6 O2 + 6 H2O Rate varies with Availability of raw materials Intensity of sunlight Temperature (best at 20-35°C / 68 - 95°F)

Photosynthesis Pigments Chlorophyll Xanthophylls Carotenes Chlorophyll a and chlorophyll b most common types. Captures light energy and feeds it into photosynthetic process Xanthophylls Yellow pigments that capture light energy and transfer it to chlorophyll a. Carotenes Orange pigments that capture light energy and transfer it to chlorophyll a.

Photosynthesis Light Reactions (Light Dependent Reactions) Light energy transferred from chlorophyll a is used to Convert some ADP to ATP Split H2O into Oxygen and High Energy Hydrogen ions. Oxygen is released into the atmosphere. ATP and Hydrogen ions are used to "fuel" the Dark Reactions (Light Independent Reactions)

Photosynthesis Dark Reactions (Light Independent Reactions) One atom of Oxygen is split from CO2. This atom combines with 2 Hydrogen ions to form H2O. Remaining Carbon and Oxygen group combine with remaining Hydrogen ions to enter the Calvin Cycle and eventually form Glucose (C6H12O6).

Photosynthesis

Chloroplast “Anatomy” Chloroplast; the organelle in which photosynthesis takes place. Chlorophyll a is the major pigment involved and is stored in the chloroplast in the thylakoids

Chloroplast “Anatomy” The light dependent reactions take place within and across the membranes of the thylakoids; an electron transport chain in the thylakoid membrane is essential! Stacks of thylakoids are called Grana The dark reactions (light-independent reactions) take place in the stroma of the chloroplast (the fluid-filled portion surrounding the thylakoids).

Cellular Respiration The process of converting stored chemical energy in food molecules to chemical energy in the form of ATP that is usable for all cellular activities. A two stage process: Stage 1 is ALWAYS glycolysis Stage 2 is either Aerobic respiration (with oxygen) Anaerobic respiration (without oxygen)

Cellular Respiration ALL living organisms carry on cellular respiration to provide energy for life processes. Autotrophs carry on cellular respiration Heterotrophs carry on cellular respiration REMEMBER … even plants carry on cellular respiration

Cellular Respiration GLYCOLYSIS Glycolysis is the breakdown of glucose to form 2 molecules of pyruvate. This process occurs in the cytoplasm of the cell. This process uses 2 molecules of ATP and makes 4 molecules of ATP to yield a total gain of 2 ATP. CELLULAR RESPIRATION ALWAYS BEGINS WITH GLYCOLYSIS!!!!!

Cellular Respiration The second stage of cellular respiration will take one of two paths depending on whether oxygen is present or absent in the cell. If oxygen is present, aerobic respiration occurs in the mitochondrion of the cell producing a LOT of ATP. If oxygen is not present, anaerobic respiration occurs in the cytoplasm of the cell producing NO additional ATP.

Cellular Respiration AEROBIC RESPIRATION Takes place in the mitochondria of the cell Pyruvate produced in glycolysis enters the mitochondria and a carbon molecule is removed. This carbon combines with oxygen to produce a molecule of CO2. The remaining portion of the pyruvate is now called an acetyl group. It combines with a molecule called Coenzyme-A to form a molecule called acetyl-CoA

Cellular Respiration AEROBIC RESPIRATION Acetyl-CoA enters the Krebs Cycle. The Krebs Cycle will produce 2 more ATP, and will "energize" 3 molecules of NADH and 1 molecule of FADH2. The NADH and FADH2 enter an electron transport chain in the mitochondrial membrane to produce another 34 ATP. Oxygen is needed to keep the electron transport chain running. It combines with Hydrogen to form water.

Cellular Respiration AEROBIC RESPIRATION Total ATP produced: Glycolysis = 2 ATP Krebs Cycle = 2 ATP Electron Transport Chain = 34 ATP Grand Total = 38 ATP C6H12O6 + 6 O2 + 6 H2O→6 CO2 + 12 H2O + 38 ATP

Cellular Respiration ANAEROBIC RESPIRATION If oxygen is not present in the cell, the electron transport chain will not function. Instead of entering the Krebs Cycle, the pyruvate produced in glycolysis will undergo fermentation. Two important types of fermentation are Lactic acid fermentation Alcoholic fermentation

Cellular Respiration ANAEROBIC RESPIRATION The end result of lactic acid fermentation is lactic acid (also called lactate) Some bacteria and fungi act anaerobically on sugars in foods to produce other foods including: cheese yogurt buttermilk Low levels of oxygen in muscle cells during heavy exercise results in anaerobic respiration and the buildup of lactic acid. This is what causes your muscles to become sore.

Cellular Respiration ANAEROBIC RESPIRATION The end result of alcoholic fermentation is ethyl alcohol (ethanol) and carbon dioxide. Many yeasts ferment (anaerobic respiration) the sugars in grains to produce other useful items: baked goods such as bread that require dough to rise. beer and wine (12% alcohol or less) "hard" liquors (require further distillation to achieve alcohol concentrations >12%) fuel for engines.

Cellular Respiration ANAEROBIC RESPIRATION Anaerobic respiration does not produce any more ATP for the cell to use. The total yield of ATP from anaerobic respiration is the 2 ATP produced during glycolysis. The "extra" ATP that could have been produced is still stored in the end products of fermentation. Ethanol is a race car fuel Cheese is a high energy food