Cellular Respiration Energy for Life

Life Needs Energy All living things need energy to carry on their life functions. How do you get energy? Energy from food molecules cannot be used directly by the cell – it must be converted to the only energy that cells can use – ATP!!

Cellular Respiration Organisms obtain energy in a few different ways, but the majority of them perform cellular respiration within the mitochondria of their cells. Energy is found within the bonds of the glucose molecule. When the glucose molecules are broken down in the mitochondria it gets converted adenosine triphosphate - (ATP)

(Electron Transport System) (Krebs Cycle)

Cellular Respiration Cellular Respiration is a very complex series of biochemical reactions but the net result can be summarized in the equation: C6H12O6 + 6O2  6CO2 + 6H2O + ATP In words this equation means: glucose and oxygen react to produce carbon dioxide and water and ATP (energy).

Aerobic vs Anaerobic C/R Notice that in order for C/R to occur it needs oxygen. Living organism that require oxygen for C/R to occur use a form called: aerobic respiration. Some living organisms (mostly bacteria) can also perform anaerobic respiration (called fermentation), which does not require oxygen. Both types of C/R produce ATP (energy) …BUT in very different amounts! Aerobic respiration produces 36 ATP from each glucose molecule whereas anaerobic produces 2 ATP. Which one is more efficient?

Anaerobic Respiration Some organisms thrive in environments with little or no oxygen, such as bogs, sewage treatment ponds, guts of animals This process is done by yeast to make bread rise and to create the alcohol in beer. It is also done in your muscles when you feel the “burn” during weight training.

Glycolysis This diagram shows the complex steps it takes to break down glucose molecules to form energy. The process of breaking down glucose is known as “Glycolysis”

Krebs Cycle and Electron Transport System This diagram shows the Kreb cycle – where byproducts of Glycolysis get further broken down to form energy and other molecules. This occurs inside the matrix of the Mitochondria. The Electron Transport System is a series of electron carries that help pump Hydrogen ions into and out of the Mitochondria.

Summary Diagram: Cellular Respiration occurs in the mitochondria. The mitochondria takes in oxygen and glucose to create energy. It also releases carbon dioxide and water molecules in the process. Carbon Dioxide, and water help photosynthesis occur within chloroplasts. Along with sunlight, the chloroplasts are able to complete the photosynthesis reactions and produce glucose – its food. Which is also used in the mitochondria. These two processes support one another.

Adaptations for Respiration Bacteria, Protists & Fungi Respiratory gases are exchanged by diffusion http://www.biologycorner.com/bio1/protista.html , http://en.wikipedia.org/wiki/Fungus , http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Eubacteria.html Plants Respiratory gases are exchanged through leaves, stems, and roots Moves in and out of cells by diffusion but leaves and stems also have openings to the environment (stomata)

Adaptations for Respiration Animals - techniques vary: Simple diffusion across cell membranes Diffusion across moist skin into a circulatory system Openings to the environment that can be flapped open and closed with a circulatory system to transport gases Specialized respiratory structures (e.g. lungs, gills) to speed exchange of respiratory gases