Photosynthesis/Respiration

Photosynthesis Process of converting the energy of sunlight into the energy in the chemical bonds of carbohydrates (sugar and starch). Process of converting light energy into chemical potential energy. Carbon dioxide + water  sugar + oxygen (need light) 6CO2 + 6H2O  (CH2O)6 + 6O2 (need light)

Respiration Conversion of chemical potential energy into usable energy (ATP). sugar + oxygen  Carbon dioxide + water (CH2O)6 + 6O2  6CO2 + 6H2O

Joseph Priestley’s Experiment Just mouse inside bell jar dead Just plant inside bell jar Mouse + plant live

Joseph Priestley’s Experiment He concluded that mouse produces something that is required by the plant. And, plant produced something the mouse required. What is this “something” that is required by mouse and plant?

Mouse vs. Plant Mouse need to eat, drink, and breathe. Plant needs water, soil, and sunlight (anything else?). Mouse needs oxygen (O2) Plant needs carbon dioxide (CO2)

Looking back to photosynthesis and respiration Product of photosynthesis is oxygen gas and sugar. Product of respiration is carbon dioxide and water. Therefore, mouse breathes out carbon dioxide and plant release oxygen. Therefore, mouse and plant are codependent of one another.

Vocabulary Autotrophs: make their own food (ex. Plants). Heterotrophs: get energy from food they eat (ex. Human). Pigment: colored substances that absorb or reflect light.

Chlorophyll: pigment found in chloroplast that absorbs red and blue and reflects green. NADP+ (nicotinamide adenine dinuceotide phosphate) (electron carrier): NADP+ could accept two high charged electrons to form NADPH which could later form ATP. ATP (Adenosine TriPhosphate): electrons could form ATP by adding phosphate group to ADP or AMP to form ATP. (adenosine Triphosphate, Diphosphate, Monophosphate). Energy trapped in ATP can be used by the cell by breaking the bond between the phosphate groups. Forming and breaking of these bonds are facilitated by enzymes.

Closer look at photosynthesis Overall equation 6CO2 + 6H2O  C6H12O6 + 6O2 Photosynthesis is process of converting light energy into chemical energy The process is divided into two separate stages Light reaction Dark reaction

Light reaction Light reactions include light absorption, electron transport, oxygen production, and ATP formation.

Light absorption Light reaction occurs in chloroplast within the photosynthetic membranes where chlorophylls are located. Photosynthetic membranes contain cluster of pigment molecules, or photosystems, that are able to capture the energy of sunlight. There are two photosystems containing several hundred chlorophyll molecules as well as a number of accessory pigments. When light energy is absorbed by these pigments, energy is passed to the reaction center of the photosystem, to a special pair of chlorophylls, where high energy electrons are released and are passed to the first of many electron carriers.

Electron Transport High energy electrons are passed from electron carriers to carriers and end up at NADP+ to form NADPH.

Oxygen production Although chlorophylls continuously release electrons it is replenished by breaking water molecules to get 4 e- and form 4 hydrogen ions and oxygen molecule.

ATP formation Hydrogen ion made from splitting of water is left inside the photosynthetic membrane. This allows a chemical gradient where inside is full of hydrogen (positively charged) and outside with little/no hydrogen ion (negatively charged). This difference is another source of energy to form ATP.

Dark reaction (Calvin Cycle) Derived by Melvin Calvin. Do not need light but doesn’t necessarily occur during dark.

The Calvin cycle is a metabolic pathway found in the stroma of the chloroplast in which carbon enters in the form of CO2 and leaves in the form of sugar.

Cellular Respiration (Glycolysis & Respiration)

Cellular Respiration (Glycolysis & Respiration) Conversion of chemical potential energy into usable energy (ATP). sugar + oxygen  Carbon dioxide + water (CH2O)6 + 6O2  6CO2 + 6H2O

Glycolysis This is anaerobic process (no oxygen) Glycolysis: glucose  2ATP + 2NADH + 2 pyruvic acid (total: 6ATP) takes place in the cytoplasm Glucose + 2ATP  2PGAL 2PGAL  4ATP + 2NADH + 2 pyruvic acid

Respiration This is an aerobic process. 1 gram of glucose  3811 calories Kreb Cycle: 2 pyruvic acid  6 CO2 + 6NADH + 2 FADH2 + 2GTP

Citric Acid Cycle

Citric Acid Cycle

Electron Transport Total of 30 ATP 2NADH  6ATP 2GTP  2ATP 2FADH2  4ATP Total of 30 ATP

Mitochondria

Chemiosmotic Pump

Organelles Make sure you know the functions of the following organelles Nucleus Ribosome Mitochondria Chloroplast Cell membrane Endoplasmic reticulum Golgi apparatus

Animal cell Plant cell Has centrioles Chloroplast Cell wall Central vacuole