Aerobic Cellular Respiration Flashcards Preview

AP Biology 2014 > Aerobic Cellular Respiration > Flashcards

Flashcards in Aerobic Cellular Respiration Deck (16):
1

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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2

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

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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4

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 

5

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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6

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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7

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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8

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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9

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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10

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

11

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

3

12

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

2

13

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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14

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

oxidative phosphorylation

15

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

oxidized, reduced 

16

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