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Cellular Respiration. Introduction/Basic Info Furlow Novi High School. Respiration. Controlled release of energy from organic compounds in cells to form adenosine triphosphate (ATP). Glycolysis is the first step in respiration.
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Cellular Respiration Introduction/Basic Info Furlow Novi High School
Respiration • Controlled release of energy from organic compounds in cells to form adenosine triphosphate (ATP) • Glycolysis is the first step in respiration • Two types of respiration: Aerobic (uses oxygen) and anaerobic (without oxygen) • Two types of anaerobic respiration: Lactic acid fermentation (humans) and alcoholic fermentation (yeast)
Respiration • Organic compounds contain stored (potential) chemical energy in their bonds • When that energy is released, cells can use it for metabolism • Glucose (from glycogen stores) typically used first as the source of energy • No glucose? Lipids next, then amino acids/proteins (only in extreme cases- i.e. starvation)
ATP- synthesized in mitochondria • Energy “currency” of life • High energy molecule that stores energy for just about every cellular process we need • Found in the cytoplasm and the nucleoplasm
ATP • Phosphate part is most important • Because of the negative charge on all the attached oxygens, there is a lot of potential energy in these bonds • Removing the last phosphate group makes the molecule much “happier” (chemically stable) • Breaking that bond releases about 7,000 calories per mole (6.02 x 1023 molecules) similar to a whole peanut!
“renewable” molecule; ATP ADP, energy to do this comes from food you eat ATP to ADP • Constantly being used and remade…estimated the more than 2 x 1026 molecules or >160kg (352lbs) of ATP is formed in the human body daily!
Glycolysis- in the cytoplasm • Glucose enters the cell via the cell membrane and stays in the cytoplasm • After a few modifications and a handful of reactions (Ch. 8) glucose eventually cleaved into 2 pyruvate (3-C) • 2 ATP molecules needed to start, 4 ATP molecules produced, net gain of 2 ATPs
Anaerobic Respiration-cytoplasm • Breakdown of organic molecules for ATP WITHOUT using oxygen • Organisms that do this only are called anaerobes • Fermentation is another word for this • Two main pathways: Alcoholic Fermentation and Lactic acid fermentation • ONLYATP gained comes from glycolysis (the step preceding fermentation)
Anaerobic RespirationLactic Acid Fermentation • Occurs in Humans—why your muscles “burn” when you workout • Normally in aerobic organisms that find themselves in a situation where oxygen is no longer available—why you breather harder when you work out • Pyruvate converted to lactate (3-C), no CO2 produced, no ATP produced • When O2 becomes available, lactate converted back to pyruvate and then pushed through the aerobic pathway
Anaerobic RespirationAlcoholic Fermentation • Occurs in yeast cells • This is a “normal” situation for the yeast • Pyruvate converted to ethanol (2-C) and CO2 is released…both waste products for the organism • Bakers’ and brewers’ yeast allows bread to rise and beer to be carbonated (most commercial beer is forcibly carbonated as well)
Aerobic Respiration-mitochondria • Most efficient pathway to produce ATP • Begins with glycolysis just like anaerobic…pyruvate enters a mitochondrion (instead of cytoplasm) to finish pathway, though • Pyruvate loses a C as CO2, becomes acetyl-CoA • Acetyl-CoA enters Kreb’s cycle where two more CO2 molecules are produced, as well as some ATP • Byproducts of Kreb’s cycle move onto electron transport chain where most ATPs are produced
Aerobic Respiration-mitochondria • Folds of the mitochondrial cristae provide huge surface area = high efficiency/production
Cellular Respiration-Summary • Can occur with or without oxygen • Aerobic is more efficient • Anaerobic--net gain of only 2 ATPs • Aerobic-- possible gain of 36 ATPs = EFFICIENT • Glycolysis and anaerobic respiration occur in the cytoplasm • Aerobic respiration occurs in the mitochondria
