Introduction/Basic Info. Respiration Controlled release of energy from organic compounds in cells to...
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Cellular RespirationIntroduction/Basic Info
RespirationControlled 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)
RespirationOrganic 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
ATPPhosphate 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!
ATP to ADP
“renewable” molecule; ATP ADP, energy to do this comes from food you eat
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 cytoplasmGlucose 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-cytoplasmBreakdown 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 RespirationLactic Acid FermentationOccurs 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 O2 becomes available, lactate converted back to pyruvate and then pushed through the aerobic pathway
Pyruvate converted to lactate (3-C), no CO2 produced, no ATP produced
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-mitochondriaMost 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 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 RespirationKreb’s Cycle-mitochondrial matrix
Aerobic Respiration-mitochondria
Folds of the mitochondrial cristae provide huge surface area = high efficiency/production
Cellular Respiration-SummaryCan 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