Aerobic Cellular Respiration Flashcards Preview

AP Biology 2014 > Aerobic Cellular Respiration > Flashcards

Flashcards in Aerobic Cellular Respiration Deck (16):

Cellular Respiration 

  • it is a process by which cells use chemical energy stored in organic molecules to regenerate ATP, which powers work 
  • it includes both aerobic (oxygen present) and anaerobic respiration (lacks oxygen)
  • aerobic respiration is the most efficient catabolic pathway in which oxygen is consumed as a reactanct along with the organic fuel 

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What are the four distinct regions of the mitochondria and what processes of aerobic respiration occur here?

  • two major processes of aerobic respiration, the Krebs Cycle and Oxidative Phosphorylation, occur in the mitochondria 
  • the four distinct areas include:
  1. outer membrane: consists of double layer of phospholipids
  2. intermembrane space: narrow area between inner and outer membranes
  3. inner membrane: also has double phospholipid bilayer, has convolutions called cristae which are infoldings that increase surface area; oxidative phosphorylation occurs here
  4. matrix: fluid material that fills the area inside the inner membrane; the Krebs Cycle and the conversion of pyruvate to acetyl CoA occur here  

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3 Stages of Cellular Respiration Overview

1. Glycolysis:

  • means "sugar splitting"
  • breaks down glucose into two molecules of pyruvate 
  • occurs in the cytosol 
  • substrate level phosphorylation 

2. Citric Acid Cycle/Krebs Cycle:

  • completes the breakdown of glucose, oxidizing the organic fuel derived from pyruvate
  • CO2 is released 
  • occurs in mitochondrial matrix 
  • substrate level phosphorylation 

3. Oxidative Phosphorylation:

  • occurs in the mitochondria 
  • powered by redox reactions of the electron transport chain located in the cristae of mitochondria 
  • accounts for most of ATP synthesis 

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What are the roles of electron carriers?

  • transport electrons from glucose in the cytosol to the mitochondrion and also transport from one part of the mitochondrion to another 
  • the carriers alternate reduced and oxidized states as they accept and donate electrons during cellular respiration 
  • NAD+ and FAD: coenzymes and electron shuttles, oxidizing agents
  • NADH and FADH2 are the reduced forms 


What is Substrate Level Phosphorylation?

  • type of chemical reaction that results in the formation of ATP by the direct transfer of a phosphate group to ADP from a reactive intermediate 
  • it serves as a fast source of ATP independent of external electron acceptors 
  • occurs primarily in the cytoplasm during glycolysis under aerobic and anaerobic conditions, but also occurs in mitochondria during Krebs Cycle
  • oxidation and phosphorylation are not coupled 

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What are the ins and outs of Glycolysis?

  • substrate level phosphorylation that occurs in the cytosol 
  • ins include glucose, 2 ATP, and 2 NAD+
  • outs include 2 ATP, 2 NADH, 2 Pyruvate 
  • ultimately a net gain of 2 ATP

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Conversion of Pyruvate into Acetyl CoA, an intermediate process 

  • pyruvate enters the mitochondria 
  • CO2 is released 
  • pyruvate gives up 2 electrons to NAD+ which is reduced to NADH
  • coenzyme A binds to what is left of pyruvate to result in Acetyl CoA (highly reactive compound), which then enters the Krebs cycle for further oxidation

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What is the Citric Acid Cycle/ Krebs Cycle?

  • substrate level phosphorylation that occurs in mitochondrial matrix 
  • the cycle oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn 
  • CO2 is a waste product 
  • includes 8 steps each catalyzed by a specific enzyme 
  • the first step: the acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate 
  • the next seven steps decompose the citrate back to oxaloacetate
  • for one molecule of glucose, there are two turns of the Krebs cycle, one for each pyruvate

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Oxidative Phosphorylation 

  • a metabolic pathway that uses energy released by the oxidation of nutrients to produce ATP 
  • involves the electron transport chain on the inner membrane of the mitochondria (ETC is in the cristae)
  • accounts for most of ATP synthesis 
  • uses electrons carried by NADH and FADH2- alternate reduced and oxidized states as they accept and donate electrons 
  • ETC's main components are multiprotein complexes 
  • Electron transfer in the ETC causes proteins to pump H+ from the matrix to the intermembrane space, forming a proton gradient and electric charge gradient

  • H+ then moves back across the membrane passing through channels in ATP synthase, which drives phosphorylation of ATP

  • water is final product

  • can produce up to about 32-34 ATP 

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Chemiosmosis and a proton-motive force 

  • chemiosmosis is the use of energy in a H+ gradient to drive cellular work; an example of this is when ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP during aerobic respiration 
  • the H+ gradient is referred to as a proton-motive force, emphasizing its capacity to do work


About how many ATP can be created from energy from one NADH?



About how many ATP can be created from energy from one FADH2?



About how much ATP can be produced from each step of aerobic respiration?

  1. glycolysis: 2
  2. citric acid cycle: 2
  3. oxidative phosphorylation: about 32 or 34

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Which step of aerobic respiration has water as its final product?

oxidative phosphorylation


During Cellular Respiration glucose is ________, and oxygen is _________. 

oxidized, reduced 


who are the main players in aerobic respiration?

  • glucose
  • mitochondria
  • electron carriers (NAD+ and FAD) 
  • ATP
  • Coenzyme A (binds to acetate to form acetyl CoA