cellular respiration Flashcards
(12 cards)
what is CR?
most important metabolic reaction
it is the process by which organic molecules are brocken down to produce energy in the from of ATP
what is the equation word/chemical
-glucose+ oxygen—> carbon dioxide+ water+ ATP
- C6H1206+ 602—-> 6CO2+6H20+ATP
where does the energy go?
60% is lost as heat- necessary to control body temp
40% forms ATP
What is ATP?
adenosine triphosphate
ATP is created when ADP combines with a phosphate group
ATP molecule consists of adenosine and a chain on 3 phosphate groups
why does CR occur? what is the energy needed for?
to produce energy in the form of ATP
ATP needed for cell division, movement of organelles, active transport, movement of whole cells
how does CR occur?
takes place in a series of events
first stage is glycolysis, 2 possible pathways depending on oxygen avaliable.
anaerobic or aerobic
describe anaerobic respiration
without oxygen
- occurs in cytoplasm
-if there continues to be no 02 the pyruvate produced in glycolysis is then converted into lactic acid by fermentation
-lactic acid is what we feel as pain and fatigue
- fermentation stage does not produce any additional ATP but glycolysis releases enough energy to convert 2 molecules of ADP into ATP
-enzymes required for anaerobic available in the cytosol of cell therefore glycolysis and the conversion of pyruvate to lactic acid occur in the cytosol.
-lactic acid goes to liver as high levels is toxic for body and gets changed into glucose. to do this 02 required- 02 dept occurs
-02 levels in blood lower and need to be repaid by converting lactic acid into glucose, done by breathing heavy for a period of time.
describe aerobic
with 02- occurs in mitochondria( on inner fold called cristae)
- cristae- made of many folds(with enzymes) to increase SA so rate of CR can be increased
- pyruvate broken down by enzymes to produce 36 ATP
- the complete break down of glucose to C02 and H20 requires 02
- one glucose molecule = 38 ATP( 2 in cytoplasm - 36 in mitochondria)
what occurs in the first stage?
glycolysis
breaksdown glucose
- produces 2 molecules of pyruvic acid and 2 ATP molecules
what occurs in the 2nd stage?
pyruvate breakdown
- takes place in mitochondrion- where enzymes are available to allow next series of reactions to occur.
-it is first converted into coenzyme A(acetyl CoA) to enter enter next pathway to do this–
- carbon dioxide molecule is removed from pyruvate and the remaining 2 carbon structures joins to coenzyme A
- NO ATP PRODUCED
- carbon x 2 acetyl COA produced
what happens in the 3rd stage of cellular respiration?
krebs cycle/ citric cycle
-occurs in the matrix of mitochondria
-carbon atoms in acetyl COA released= go back to being CO2
- acetyl COA further broken down
- 1 molecule of ATP produced for every acetyl COA that enters this cycle- meaning 2 ATP molecules produced per glucose molecule.
what happens in the 4th stage?
electron transport system
- only stage that uses 02
- electrons passed between molecules, resulting in 02 molecules forming water
-02 must be present to accept the electrons at end of chain and combine with hydrogen ions
- aerobic respiration of 1 molecule of glucose has potential to generate up to 38 molecules of ATP in cytoplasm, therefore 36 in mitochondria.
