Post on 03-Jan-2016
Cellular Respiration (Chapter 9)
Energy source Autotrophs: Producers Plants, algae and some bacteria Make own organic molecules Heterotrophs: Consumers
Energy All activities an organism performs
requires energy
Cellular respiration
C6H12O6 + 6 O2
---> 6 CO2 + 6 H2O + ATP
Cellular respiration
Cellular Respiration Catabolic 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 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 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
Redox reaction
becomes oxidized
becomes reduced
Vocabulary 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+
2 e− + 2 H+
2[H](from food)
Nicotinamide(oxidized form)
Reduction of NAD+
2 e− + H+
NADH
Nicotinamide(reduced form)
Oxidation of NADHH+
H+
Dehydrogenase
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
H+
2
H+
ADP + P i ATP
Chemiosmosis
ATPsynthase
ATP Synthase Enzyme helps make ATP Located in membrane Changes ADP to ATP Uses energy from a proton
gradient across membrane
INTERMEMBRANESPACE
RotorH+ Stator
Internal rod
Catalyticknob
ADP+P i
MITOCHONDRIALMATRIX
ATP
The Reactions (Cell Respiration)
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 Every living organism can carry
out glycolysis Occur in aerobic & anaerobic Does not require oxygen Oxygen present the Krebs cycle
will begin
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: Energy Investment Phase
Glucose
GLYCOLYSIS: Energy Investment Phase
Glucose6-phosphate
ATP
ADPGlucose
Hexokinase
1
GLYCOLYSIS: Energy Investment Phase
Glucose6-phosphate
ATP
ADPGlucose
Hexokinase Phosphogluco-isomerase
Fructose6-phosphate
12
GLYCOLYSIS: Energy Investment Phase
3
Fructose6-phosphate
ATP
ADP
Fructose1,6-bisphosphate
Phospho-fructokinase
GLYCOLYSIS: Energy Investment Phase
34
5
Fructose6-phosphate
ATP
ADP
Glyceraldehyde3-phosphate (G3P)
Fructose1,6-bisphosphate
Dihydroxyacetonephosphate (DHAP)
Phospho-fructokinase
Aldolase
Isomerase
GLYCOLYSIS: Energy Investment Phase
ADP
Glucose6-phosphate
Fructose6-phosphate
ATP ATP
ADP
Glyceraldehyde3-phosphate (G3P)
Fructose1,6-bisphosphate
Dihydroxyacetonephosphate (DHAP)
Glucose
Hexokinase Phosphogluco-isomerase
Phospho-fructokinase
Aldolase
Isomerase
12
5
43
GLYCOLYSIS: Energy Payoff Phase
4
Glyceraldehyde3-phosphate (G3P)
Dihydroxyacetonephosphate (DHAP)
Aldolase
Isomerase
5 6
Triosephosphate
dehydrogenase
2 NAD+ 2 H+
NADH
2
2
2
2
1,3-Bisphospho-glycerate
GLYCOLYSIS: Energy Payoff Phase
4
Glyceraldehyde3-phosphate (G3P)
Dihydroxyacetonephosphate (DHAP)
Aldolase
Isomerase
5 67
Triosephosphate
dehydrogenase
2 NAD+ 2 H+
NADH
2
2
2
2
2 ADP
1,3-Bisphospho-glycerate
3-Phospho-glycerate
Phospho-glycerokinase
2
2
ATP
8 9
Phospho-glyceromutase
3-Phospho-glycerate
2-Phospho-glycerate
2 2 2
Enolase
Phosphoenol-pyruvate (PEP)
2 H2O
GLYCOLYSIS: Energy Payoff Phase
Figure 9.9bb-3
8 9 10
Phospho-glyceromutase
3-Phospho-glycerate
2-Phospho-glycerate
2 2 2
Enolase
Phosphoenol-pyruvate (PEP)
Pyruvate
Pyruvatekinase
2
2 ATPADP
2 H2O 2
GLYCOLYSIS: Energy Payoff Phase
GLYCOLYSIS: Energy Payoff Phase
Glycer-aldehyde
3-phosphate(G3P)
Triosephosphate
dehydrogenase
6 1,3-Bisphospho-glycerate
3-Phospho-glycerate
2-Phospho-glycerate
Phosphoenol-pyruvate (PEP)
Pyruvate
Phospho-glycerokinase
Phospho-glyceromutase
Enolase Pyruvatekinase
2 NAD+
7 89
10
2 NADH
+ 2 H+
2
2
2
2
2 2 22
2
22 H2OATP ATPADPADP
Electron shuttlesspan membrane
+ 2 ATP
2 NADHor
2 FADH2
GLYCOLYSIS
Glucose 2Pyruvate
2 NADH
Glycolysis Glucose
converted to pyruvate.
First half uses 2 ATP
Forms 2 separate G3P (glyceraldehyde 3-phosphate)
Glycolysis Second half
generates 4 ATP, 2 NADH & 2 pyruvate
Net results are 2 ATP, 2 NADH and 2 pyruvate
Takes place in the cytoplasm
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