Introduction/Basic Info

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 contained 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 molecules) similar to a whole peanut!

ATP to ADP “renewable” molecule;ATPADP, energy to do this comes from food you eat Constantly being used and remade…estimated the more than 2 x 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 ONLY ATP comes from glycolysis

Anaerobic Respiration Lactic 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 When O 2 becomes available, lactate converted back to pyruvate and then pushed through the aerobic pathway Pyruvate converted to lactate (3-C), no CO 2 produced, no ATP produced

Anaerobic Respiration Alcoholic Fermentation Occurs in yeast cells This is a “normal” situation for the yeast Pyruvate converted to ethanol (2-C) and CO 2 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 to finish pathway though Pyruvate loses a C as CO2, becomes acetyl-CoA Acetyl-CoA enters Kreb’s cycle where two more CO 2 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 Kreb’s Cycle- mitochondrial matrix

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 (net gain of 2 ATPs vs possible gain of 36 ATPs) Glycolysis and anaerobic respiration occur in the cytoplasm Aerobic respiration occurs in the mitochondria