Biology The Working Cell: Energy From Food

Sunlight Powers Life There are 2 main types of organisms: 1. Autotrophs are organisms that make their own food from CO 2 and an energy source such as sunlight. Ex Plants, algae, and some bacteria. Autotrophs are the producers b/c they produce their own food & food for other organisms (they do NOT produce their own energy).

There are 2 types of autotrophs: Photoautotrophs: organisms that use sunlight (photosynthesis) to produce their own food (plants, algae, and some bacteria). Chemoautotrophs: organisms that use inorganic chemicals/compounds (chemosynthesis) to produce their own food (bacteria). m/palm-tree.jpg/palm-tree-full.jpg nobacteria.png 2.jpg _coli a%5B1%5D.jpg

Heterotrophs are organisms that cannot produce their own and must consume (eat other organisms); therefore they are consumers. Ex animals, fungi, and many unicellular organisms. com/000802_c824_0023_csls.jpg 1/OCEnotes/shark2.jpg

All organisms perform some type of cellular respiration –Conversion of sugar & O 2 into usable chemical energy (ATP) –By-products are CO 2 & H 2 O

Energy Terms: Kinetic energy: energy of motion Potential energy: stored energy Thermal energy: random molecular motion; when transferred produces heat Chemical energy: form of potential energy (macromolecules & ATP) Calorie: amount of energy needed to raise the temp of 1 g of H 2 O by 1˚C; kilocalories = 1,000 cal Cellular respiration is a slow ‘burn’ where heat is produced.

ATP Life depends on energy. Compounds that store energy: ATP, NADPH, NADH, & FADH 2. ATP= adenosine triphosphate is the energy currency of the cell (cash of the cell; main energy of the cell for chemical reactions) Every time a bond holding a phosphate group (PO 3 ) is broken energy is released; therefore every time ATP losses a PO 3, energy is released. ATP can be used for ALL types of cellular work.

Energy from chemical reactions  Energy for chemical reactions  ATP is constantly needed b/c cells are constantly working. ATP is continuously broken down and recycled very rapidly (used and remade).

Cellular Respiration Cellular Respiration is the process of breaking down glucose molecules through a series of steps to release energy. –This produces ATP. –Occurs in the mitochondria This can occur in the presence of O 2 (aerobic respiration) or without O 2 (anaerobic respiration).

Aerobic respiration produces 36 ATP molecules whereas anaerobic respiration produces only 2 ATP. The overall equation of cellular respiration: C 6 H 12 O O 2  6CO 2 + 6H 2 O + energy Metabolism: all of the cell’s chemical reactions

Mitochondria (Sing. Mitochondrion) Double membrane (outer & inner); both involved in cellular respiration Cristae: folds of inner membrane (increasing surface area) Matrix: space within the inner membrane

There are 3 Phases of Aerobic Respiration: 1. Glycolysis: Whether the organism is aerobic or anaerobic, that organism will undergo glycolysis. This is always the 1st step! Glucose is converted to pyruvate (a 3-C compound) and 2 ATP are released. This occurs in the cytoplasm This occurs in 10 steps; 2 phases The final results are: 2 NADH, 2 ATP, and 2 pyruvate

2.Krebs Cycle: This is a.k.a. the citric acid cycle Pyruvate is converted into acetyl-CoA and CO 2 is released Acetyl-CoA enters the Krebs cycle This occurs in the mitochondria (matrix) 2 ATP, NADH, and FADH 2 are released. For every glucose molecule, 2 pyruvate are produced. 1 ATP is made for each pyruvate; therefore a total of 2 ATP are made.

3.Electron Transport: Both NADH and FADH 2 enter the electron transport This occurs in the mitochondria (cristae) This is the only part that REQUIRES OXYGEN. Prior to this ONLY 4 ATP have been made, yet a total of 36 ATP can be made during aerobic respiration. That means 32 ATP can be made here. This is the cash cow of cellular respiration! Energy is transferred from NADH and FADH 2 to ATP. Water is produced as a by-product as well as heat.

Anaerobic Respiration (w/o O 2 ): Fermentation is the extraction of energy from pyruvate without O 2. Alcohol fermentation is the conversion of pyruvate to CO 2 and ethanol (yeast, a unicellular fungi, performs this). Lactic acid fermentation is the conversion of pyruvate to lactic acid during strenuous exercise when there isn’t enough O 2 (animal muscle cells perform this). –This is why muscles become fatigued and sore after strenuous exercising. Calories are the amount of heat energy needed to raise the temperature of 1 gram of water 1 degree C. –This is the energy contained in food substances.

THE END!

This slide show was developed by Dana Halloran, Cardinal Mooney High School, Sarasota, FL. Used with her personal permission, adapted and amended by Rosa Whiting, Manatee School for the Arts, Palmetto, FL.