BiologyThe Working Cell: Energy From Food

Sunlight Powers LifeThere are 2 main types of organisms:1. Autotrophs are organisms that make their own food from CO2 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).

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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).

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http://www.clcbio.com/scienceimages/cyanobacteria.pnghttp://gas2.org/files/2008/03/algae-

2.jpg

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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.

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• All organisms perform some type of cellular respiration

– Conversion of sugar & O2 into usable chemical energy (ATP)

– By-products are CO2 & H2O

http://www.tomatosphere.org/teacher-resources/teachers-guide/grades-8-10/images/photosynthesis-respiration.jpg

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 H2O 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, & FADH2.

• 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 (PO3) is broken energy is released; therefore every time ATP losses a PO3, energy is released.

• ATP can be used for ALL types of cellular work.

Energy from chemical reactions

Energy for chemical reactions

http://library.thinkquest.org/C006669/media/Biol/img/atp_cycle.gif

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 O2 (aerobic respiration) or without O2 (anaerobic respiration).

• Aerobic respiration produces 36 ATP molecules whereas anaerobic respiration produces only 2 ATP.

The overall equation of cellular respiration:

C6H12O6 + 6 O2 6CO2 + 6H2O + energy

• Metabolism: all of the cell’s chemical reactions

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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

http://www.cartage.org.lb/en/themes/sciences/zoology/AnimalPhysiology/Anatomy/AnimalCellStructure/Mitochondria/mitochondria.jpg

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 CO2 is released

• Acetyl-CoA enters the Krebs cycle

• This occurs in the mitochondria (matrix)

• 2 ATP, NADH, and FADH2 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 FADH2 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 FADH2 to ATP.

• Water is produced as a by-product as well as heat.

http://fig.cox.miami.edu/~cmallery/150/makeatp/c9x6cell-respiration.jpg

Anaerobic Respiration (w/o O2):

• Fermentation is the extraction of energy from pyruvate without O2.

• Alcohol fermentation is the conversion of pyruvate to CO2 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 O2 (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.

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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.