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Cellular Respiration (Chapter 9)
Energy Plants, algae & some bacteria Convert radiant energy (sun) into
chemical energy (glucose)
Harvest Energy All activities an organism performs
requires energy
Catabolism Enzymes break down substances Harvest energy from C-H bonds Or other chemical bonds
Organic compounds + oxygen ⇨ Carbon Dioxide + water +
energy
Cellular respiration Aerobic respiration Chemical energy is harvested
from food Presence of oxygen Anaerobic respiration Process occurs without oxygen Fermentation
Anaerobic Glucose to lactate (muscle cells) Glucose to alcohol (yeast cells) Does not yield as much energy
Cellular respiration
Cellular respiration
C6H12O6 + 6 O2
---> 6 CO2 + 6 H2O + ATP
Cellular Respiration Exergonic -686kcal/mole (-2,870kJ/mole) Redox reaction Glucose is oxidized, oxygen is reduced Energy stored in glucose makes ATP 38 ATP generated ATP stores energy for use in cellular
functions
Vocabulary (Cell respire) NAD/NADH FAD ETC Phosphorylation Chemiosmosis ATP Synthase
NAD & NADH NAD: Nicotinamide adenine dinucleotide NAD+ oxidized form NADH reduced form NAD+ traps electrons from glucose Function as energy carrier
NAD & NADH Dehydrogenase (enzyme) Removes a pair of hydrogen atoms
from glucose Transfers one proton and 2
electrons to NAD+
H-C-OH + NAD+ ⇨ -C=O + NADH + H+
Used to make ATP
NAD & NADH
FAD Flavin adenine dinucleotide Transfers electrons
Electron transport chain Located inner membrane of
mitochondria Plasma membrane (prokaryotes) Series of molecules (mostly
proteins)
Electron transport chain Electrons fall to oxygen In a series of energy releasing
steps High potential energy to low Energy released generates ATP
Electron transport chain
Fre
e en
erg
y, G
Controlledrelease ofenergy for
synthesis ofATP
2 H+ + 2 e–
2 H + 1/2 O2
(from food via NADH)
ATP
ATP
ATP
1/2 O22 H+
2 e–E
lectron
transp
ort
chain
H2O
Phosphorylation Addition of a phosphate group to a
molecule ATP is formed by a
phosphorylation reaction 1. Substrate-level phosphorylation 2. Oxidative phosphorylation
Substrate phosphorylation Enzyme transfers
a phosphate from a organic substrate molecule
ADP to make ATP Direct formation Glycolysis and
Krebs cycle
Oxidation phosphorylation Energy from
electron transport chain
Synthesis ATP Adds an
inorganic phosphate to ADP
Chemiosmosis Energy-coupling mechanism Energy stored in hydrogen ion
gradient across membrane Makes ATP from ADP
ATP Synthase Enzyme helps make ATP Located in membrane Changes ADP to ATP Uses energy from a proton
gradient across membrane
The Reactions---Cell respire Glycolysis Krebs cycle (citric acid cycle) Electron transport chain (oxidative
phosphorylation)
Cellular respiration
Glycolysis Happens in cytoplasm Starts with glucose Yields 2 pyruvate (3 carbons)
molecules, 4 ATP (net of 2 ATP) & 2 NADH
10 enzyme catalyzed reactions to complete
Glycolysis Part one (priming) First 5 reactions are endergonic 2 ATP molecules attach 2
phosphate groups to the glucose Produces a 6 carbon molecule
with 2 high energy phosphates attached
Glycolysis Part two (cleavage reactions) 6 carbon molecule is split into 2 3-carbon molecules each with a
phosphate (G3P)
Glycolysis Part three (energy harvesting
reactions) In two reactions 2- G3P molecules
are changed to pyruvate 4 ATP molecules are made (net of
2) An energy rich hydrogen is
harvested as NADH (2NADH)
Glycolysis Every living organism can carry
out glycolysis Occur in aerobic & anaerobic Does not require oxygen Oxygen present the Krebs cycle
will begin
Fig. 9-9-1
ATP
ADP
Hexokinase1
ATP
ADP
Hexokinase1
Glucose
Glucose-6-phosphate
Glucose
Glucose-6-phosphate
Fig. 9-9-2
Hexokinase
ATP
ADP
1
Phosphoglucoisomerase2
Phosphogluco-isomerase
2
Glucose
Glucose-6-phosphate
Fructose-6-phosphate
Glucose-6-phosphate
Fructose-6-phosphate
1
Fig. 9-9-3
Hexokinase
ATP
ADP
Phosphoglucoisomerase
Phosphofructokinase
ATP
ADP
2
3
ATP
ADP
Phosphofructo-kinase
Fructose-1, 6-bisphosphate
Glucose
Glucose-6-phosphate
Fructose-6-phosphate
Fructose-1, 6-bisphosphate
1
2
3
Fructose-6-phosphate
3
Fig. 9-9-4
Glucose
ATP
ADP
Hexokinase
Glucose-6-phosphate
Phosphoglucoisomerase
Fructose-6-phosphate
ATP
ADP
Phosphofructokinase
Fructose-1, 6-bisphosphate
Aldolase
Isomerase
Dihydroxyacetonephosphate
Glyceraldehyde-3-phosphate
1
2
3
4
5
Aldolase
Isomerase
Fructose-1, 6-bisphosphate
Dihydroxyacetonephosphate
Glyceraldehyde-3-phosphate
4
5
Fig. 9-9-52 NAD+
NADH2
+ 2 H+
2
2 P i
Triose phosphatedehydrogenase
1, 3-Bisphosphoglycerate
6
2 NAD+
Glyceraldehyde-3-phosphate
Triose phosphatedehydrogenase
NADH2
+ 2 H+
2 P i
1, 3-Bisphosphoglycerate
6
2
2
Fig. 9-9-62 NAD+
NADH2
Triose phosphatedehydrogenase
+ 2 H+
2 P i
2
2 ADP
1, 3-Bisphosphoglycerate
Phosphoglycerokinase2 ATP
2 3-Phosphoglycerate
6
7
2
2 ADP
2 ATP
1, 3-Bisphosphoglycerate
3-Phosphoglycerate
Phosphoglycero-kinase
2
7
Fig. 9-9-7
3-Phosphoglycerate
Triose phosphatedehydrogenase
2 NAD+
2 NADH+ 2 H+
2 P i
2
2 ADP
Phosphoglycerokinase
1, 3-Bisphosphoglycerate
2 ATP
3-Phosphoglycerate2
Phosphoglyceromutase
2-Phosphoglycerate2
2-Phosphoglycerate2
2
Phosphoglycero-mutase
6
7
8
8
Fig. 9-9-82 NAD+
NADH2
2
2
2
2
+ 2 H+
Triose phosphatedehydrogenase2 P i
1, 3-Bisphosphoglycerate
Phosphoglycerokinase
2 ADP
2 ATP
3-Phosphoglycerate
Phosphoglyceromutase
Enolase
2-Phosphoglycerate
2 H2O
Phosphoenolpyruvate
9
8
7
6
2 2-Phosphoglycerate
Enolase
2
2 H2O
Phosphoenolpyruvate
9
Fig. 9-9-9
Triose phosphatedehydrogenase
2 NAD+
NADH2
2
2
2
2
2
2 ADP
2 ATP
Pyruvate
Pyruvate kinase
Phosphoenolpyruvate
Enolase2 H2O
2-Phosphoglycerate
Phosphoglyceromutase
3-Phosphoglycerate
Phosphoglycerokinase
2 ATP
2 ADP
1, 3-Bisphosphoglycerate
+ 2 H+
6
7
8
9
10
2
2 ADP
2 ATP
Phosphoenolpyruvate
Pyruvate kinase
2 Pyruvate
10
2 P i
Oxidation of pyruvate Pyruvate is changed into acetyl-
CoA First carboxyl group is removed Leaves as carbon dioxide 2 carbon molecule called acetate
remains
Oxidation of pyruvate Pyruvate dehydrogenase Multienzyme complex Combines acetate (acetyl group)
with a coenzyme called coenzyme A.
Product is acetyl-CoA Plus one NADH
Oxidation of pyruvate Pyruvate dehydrogenase Largest known enzyme 60 subunits Process occurs within mitochondria Acetyl-CoA is end product of the
break down of fats and proteins too
Fig. 9-10
CYTOSOL MITOCHONDRION
NAD+ NADH + H+
2
1 3
Pyruvate
Transport protein
CO2Coenzyme A
Acetyl CoA