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# Cellular Respiration There are 2 types of cellular respiration: ## Aerobic Respiration * Requires oxygen to fully release all energy from carbohydrates, protein, or lipids * Results in a net gain of 36 or 38 ATP molecules * Carbon dioxide is produced as a waste product * This is why we breathe ox...

# Cellular Respiration There are 2 types of cellular respiration: ## Aerobic Respiration * Requires oxygen to fully release all energy from carbohydrates, protein, or lipids * Results in a net gain of 36 or 38 ATP molecules * Carbon dioxide is produced as a waste product * This is why we breathe oxygen in and carbon dioxide out * Exercise increases our efficiency of getting oxygen to our cells and removing carbon dioxide ## Anaerobic Respiration * Occurs when oxygen is not available * Some organisms use this all of the time (some bacteria and yeast) * Either 2 lactic acid (in animals) or alcohol (in yeast and bacteria) are made for every glucose molecule * Alcohol is used in beer, wine, liquor, cheese, yogurt * Lactic acid builds up in our muscles so we feel sore when we perform an exercise level we are not used to * Anaerobic respiration is also known as **fermentation** - we use it for breads, sausages, yogurt, buttermilk, etc. * Only 2 ATP molecules are made for each glucose, so it is not as energy efficient (about 2%) * No matter how great of shape you are in, after exercise, we all have lactic acid in our muscles * How fast we clear it is a measure of how good shape we are in ## Obligate Anaerobes * Carry out fermentation or anaerobic respiration and cannot survive in the presence of O2 * Yeast and many bacteria are facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration ## Facultative Anaerobes * In a facultative anaerobe, pyruvate is a fork in the metabolic road that leads to two alternative catabolic routes. ## Carbohydrate Metabolism * Requires oxygen to occur fully * Breaks down 2 pyruvate molecules down into 6 carbon dioxide molecules and 36 ATP * If mitochondria runs out of glucose, the TCA cycle can accept amino acids and triglyceride (fatty acid) fragments to produce ATP, so this is why low carbohydrate diets work * When burning fat, ketone bodies are formed instead of pyruvic acid, some ketones spill into urine = ketosis * Carbohydrate metabolism produces fast energy, glucose from a carbohydrate meal is usually used up in 30 to 60 minutes after meal.