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Cellular Respiration Chapter 7

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Cellular Respiration Chapter 7 An overview of cellular respiration Figure 6.8 High-energy electrons carried by NADH GLYCOLYSIS Glucose Pyruvic acid KREBS CYCLE ... – PowerPoint PPT presentation

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Title: Cellular Respiration Chapter 7


1
Cellular RespirationChapter 7
2
  • An overview of cellular respiration

High-energy electrons carried by NADH
GLYCOLYSIS
ELECTRONTRANSPORT CHAINAND CHEMIOSMOSIS
KREBSCYCLE
Glucose
Pyruvicacid
Cytoplasmicfluid
Mitochondrion
Figure 6.8
3
PREPARATORYPHASE(energy investment)
Steps A fuelmolecule is
energized,using ATP.
Glucose
1
3
  • Details of glycolysis in the cytoplasm

Step
1
Glucose-6-phosphate
2
Fructose-6-phosphate
3
Fructose-1,6-diphosphate
Step A six-carbonintermediate splits into
two three-carbon intermediates.
4
4
Glyceraldehyde-3-phosphate (G3P)
ENERGY PAYOFF PHASE
5
Step A redoxreaction generatesNADH.
5
1,3-Diphosphoglyceric acid(2 molecules)
6
Steps ATPand pyruvic acidare produced.
3-Phosphoglyceric acid(2 molecules)
6
9
7
2-Phosphoglyceric acid(2 molecules)
8
2-Phosphoglyceric acid(2 molecules)
9
Pyruvic acid
(2 moleculesper glucose molecule)
Figure 6.9B
4
What happens if oxygen is not present?
  • Fermentation
  • Occurs in the cytosol
  • Generate NAD for recycling to glycolysis
  • No ATP production
  • Lactic acid and alcoholic fermentation

5
Lactic acid fermentation and alcoholic
fermentation
6
Efficiency of glycolysis and fermentation
7
When Oxygen is present Pyruvic acid is
chemically groomedfor the Krebs cycle which
takes place in the mitochondria
  • In the matrix of the mitochondria, each pyruvic
    acid molecule is broken down to form CO2 and a
    two-carbon acetyl group, which enters the Krebs
    cycle

Pyruvicacid
Acetyl CoA(acetyl coenzyme A)
CO2
Figure 6.10
8
When Oxygen is present The Krebs cycle completes
the oxidation of organic fuel, generating many
NADH and FADH2 molecules
Acetyl CoA
  • The Krebs cycle, in the matrix of the
    mitochondria, is a series of reactions in which
    enzymes strip away electrons and H from each
    acetyl group

2
KREBSCYCLE
CO2
Figure 6.11A
9
2 carbons enter cycle
Oxaloaceticacid
1
Citric acid
CO2 leaves cycle
5
KREBSCYCLE
2
Malicacid
4
Alpha-ketoglutaric acid
3
CO2 leaves cycle
Succinicacid
Step Acetyl CoA stokesthe furnace
Steps and NADH, ATP, and CO2 are
generatedduring redox reactions.
Steps and Redox reactions generate
FADH2and NADH.
1
2
3
4
5
Figure 6.11B
10
Chemiosmosis powers most ATP production in the
inner membrane
  • The electrons from NADH and FADH2 travel down the
    electron transport chain to oxygen
  • Energy released by the electrons is used to pump
    H into the space between the mitochondrial
    membranes
  • In chemiosmosis, the H ions diffuse back through
    the inner membrane through ATP synthase
    complexes, which capture the energy to make ATP

11
  • Chemiosmosis in the mitochondrion inner membrane

Proteincomplex
Intermembranespace
Electroncarrier
Innermitochondrialmembrane
Electronflow
Mitochondrialmatrix
ELECTRON TRANSPORT CHAIN
ATP SYNTHASE
Figure 6.12
12
Connection Certain poisons interrupt critical
events in cellular respiration
Rotenone
Oligomycin
Cyanide,carbon monoxide
ELECTRON TRANSPORT CHAIN
ATP SYNTHASE
Figure 6.13
13
Review Each molecule of glucose yields many
molecules of ATP
  • For each glucose molecule that enters cellular
    respiration, chemiosmosis produces up to 38 ATP
    molecules

Cytoplasmic fluid
Mitochondrion
Electron shuttleacrossmembranes
KREBSCYCLE
GLYCOLYSIS
2AcetylCoA
KREBSCYCLE
ELECTRONTRANSPORT CHAINAND CHEMIOSMOSIS
2Pyruvicacid
Glucose
by substrate-levelphosphorylation
used for shuttling electronsfrom NADH made in
glycolysis
by substrate-levelphosphorylation
by chemiosmoticphosphorylation
Maximum per glucose
Figure 6.14
14
Fermentation is an anaerobic alternative to
aerobic respiration
  • Under anaerobic conditions, many kinds of cells
    can use glycolysis alone to produce small amounts
    of ATP
  • But a cell must have a way of replenishing NAD
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