biochemistry bioenergetics: how the body converts food to energy
TRANSCRIPT
Biochemistry
Bioenergetics:How the body converts
food to energy
Bioenergetics
MetabolismMetabolism: The sum of all Chemical Reactions involved in maintaining the dynamic state of the cell– CatabolismCatabolism - breaking down of molecules to
supply energy– AnabolismAnabolism - synthesis of molecules– Biochemical Pathway Biochemical Pathway - a series of consecutive
chemical reactions
Common Catabolic Pathway
Conversion of FOOD to ATP:
FOOD produces C4 and C2 fragments
C4 and C2 fragments enter Citric Acid Cycle
CO2, NADH, FADH2, are produced
Electron Transport Electron Transport produces ATP
O2 O2
Citric AcidCycle
CC22
CC22
CC22
CO2
CO2
CO2
CC44CC44
NADH
FADH2
ATP
ATPATP
ATP
ATPH2O
outermembrane
innermembrane
e- tra
nspo
rt
e- tra
nspo
rt
Cells and Mitochondria
Components of a typical cell: nucleus - replication of cell begins here
lysosomes - remove damaged cellular components
Golgi bodies - package and transport proteins
organelles - specialized structures with specific function
mitochondria - common catabolic pathway
Cells and Mitochondria
Cells and Mitochondria
Mitochondria
MitochondriaMitochondria
– Two membranes
– Common Catabolic Pathway
– Enzymes located in folds or “CristaCrista”
– Transport thru the inner membrane occurs with
the help of Protein GatesProtein Gates
Mitochondrion
Common Catabolic Pathway
2 Parts: Citric Acid Cycle
– or Tricarboxylic Acid Cycle– or TCA cycle– or Kreb’s Cycle
Oxidative Phosphorylation– or Electron Transport– or Respiratory Chain
1
2
Compounds - ADP
Adenosine diphosphate (ADP)
adenosine diphosphate
CH2
OHOH
OO
N
N N
N
NH2
P
O
O-
OP
O
O-
O-
diphosphate
adenosine
adenine
ribose
Compounds - ATP
AMP, ADP, ATPHigh energy phosphate anhydride bonds
CH2
OHOH
OO
N
N N
N
NH2
P
O
O-
OP
O
O-
OP
O
O-
O-
triphosphate
Compounds - ATP
ATP– We make about 88 lbs. of ATP a day!!!– Used for:
» muscle contraction
» nerve signal conduction
» biosynthesis
CH2
OHOH
OO
N
N N
N
NH2
P
O
O-
OP
O
O-
OP
O
O-
O-
Fig. 26.6, p.651
Compounds - Redox
NAD+ and FAD– Oxidizing agents– Actually coenzymes– Contain an ADP core (part of R or R’)
N+
R
C NH2
O
NAD+
N
N
NC
NHC
H3C
H3C
O
R'
O
FAD
Compounds - Redox
NAD+ is converted to NADH
Oxidized form Reduced form
N+
R
C NH2
O
+ H+ + 2 e-NR
C NH2
OH H
to ET
Compounds - Redox
FAD is converted to FADH2
Oxidized form
Reduced form
N
N
NC
NHC
H3C
H3C
O
R'
O
+ 2 H+ + 2 e-
N
N
NC
NHC
H3C
H3C
O
R'
O
H
H
to ET
Compounds
The AcetylAcetyl carrying group - Acetyl coenzyme A Carrying handle is Pantothenic Acid and
Mercaptoethylamine
CCH3 S
O
CoA
acetyl CoA
Coenzyme A
CCH3 S
O
CoA
acetyl CoA
mercaptoethylamine
CH2
OHO3PO
OO
N
N N
N
NH2
P
O
O-
OP
O
O-
OC CH C CH2NH
O
CH2CH2C
O
OH CH3
CH3
CH2CH2 NHHS
pantothenic acid ADP
-
Coenzyme A
CCH3 S
O
CoA
acetyl CoA
mercaptoethylamine
CH2
OHO3PO
OO
N
N N
N
NH2
P
O
O-
OP
O
O-
OC CH C CH2NH
O
CH2CH2C
O
OH CH3
CH3
CH2CH2 NHHS
pantothenic acid ADP
-
4C4C3C3C2C2C
Fig. 26.8, p.652
http://www.youtube.com/watch?v=iXmw3fR8fh0
http://www.youtube.com/watch?v=lvoZ21P4JK8
http://www.youtube.com/watch?v=A1DjTM1qnPM
http://www.youtube.com/watch?v=FgXnH087JIk
Citric Acid Cycle
Acetyl CoA contains a 2 carbon fragment that is carried into the Citric Acid Cycle
Also called the:– Tricarboxylic Acid Cycle– TCA Cycle– Kreb’s Cycle
Acetyl group is split out as CO2
C5
CO2C4
C4 C6
CO2
C2
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Citric Acid Cycle
Step 1– oxaloacetate will show up in last step– acetyl CoA is the THIO ESTER of acetic acid (CoA
is Co Enzyme A)
CCH3 S-CoA
O
COO-
CH2
C
COO-
O
oxaloacetate acetyl CoA
+
citratesynthetase
citryl CoA
C
C
CH2
S-CoA
COO-
CH2
COO-HO
O
CCH3 S-CoA
O
COO-
CH2
C
COO-
O
oxaloacetate acetyl CoA
+
citratesynthetase
citryl CoA
C
C
CH2
S-CoA
COO-
CH2
COO-HO
O
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Citric Acid Cycle
Step 1B– citrate or citric acid produced– citrate has 6 C (How many acid groups?)
citryl CoA
C
CCH2
S-CoAO
COO-
CH2
COO-HO +H2O
citrate
C
CCH2
OO-
COO-
CH2
COO-HO + HS-CoA
citryl CoA
C
CCH2
S-CoAO
COO-
CH2
COO-HO +H2O
citrate
C
CCH2
OO-
COO-
CH2
COO-HO + HS-CoA
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Citric Acid Cycle
Step 2– dehydration to cis-Aconitate– hydration to isocitrate– enzymes required for each Rx
citrate
C
CCH2
OO-
COO-
CH2
COO-HOaconitase
C
CCH2
OO-
COO-
CH
COO-
cis-aconitate
-H2O
aconitase
+ H2OC
CCH2
OO-
COO-
CH
COO-H
HO
isocitratecitrate
C
CCH2
OO-
COO-
CH2
COO-HOaconitase
C
CCH2
OO-
COO-
CH
COO-
cis-aconitate
-H2O
aconitase
+ H2OC
CCH2
OO-
COO-
CH
COO-H
HO
isocitrate
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Citric Acid Cycle
Step 3– oxidation and decarboxylation
– CO2 is from the ???
C
CCH2
OO-
COO-
CH
COO-H
HO
isocitrate
isocitratedehydrogenase
-ketoglutarate
C
CCH2
OO-
COO-
C
H H
O
+ CO2
NAD+ NADH
C
CCH2
OO-
COO-
CH
COO-H
HO
isocitrate
isocitratedehydrogenase
-ketoglutarate
C
CCH2
OO-
COO-
C
H H
O
+ CO2
NAD+ NADH
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Citric Acid Cycle
Step 4 – Where did the CO2 come from???
-ketoglutarate
C
CCH2
OO-
COO-
C
H H
O
enzymesystem
complex
C
CCH2
SCoA
C
H H
OO-
O
+ CO2
succinyl CoA
+ SCoA
NAD+ NADH
-ketoglutarate
C
CCH2
OO-
COO-
C
H H
O
enzymesystem
complex
C
CCH2
SCoA
C
H H
OO-
O
+ CO2
succinyl CoA
+ SCoA
NAD+ NADH
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Citric Acid Cycle
Step 5– GTP is Guanosine triphosphate (as good as ATP!)
C
CCH2
SCoA
C
H H
OO-
O
succinyl CoA
+ GDP
enzymesystem
complex
C
CCH2
OO-
C
H H
OO-
succinate
+ GTP+ SCoA
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Citric Acid Cycle
Step 6– Oxidation with FAD– Fumaric Acid is trans-Fumaric Acid – Barbiturate is an inhibitor of Succinate dehydrogenase
C
CCH2
OO-
C
H H
OO-
succinate
succinatedehydrogenase
C
CCH
OO-
C
H
OO-
fumarateFAD FADH2
C
CCH2
OO-
C
H H
OO-
succinate
succinatedehydrogenase
C
CCH
OO-
C
H
OO-
fumarateFAD FADH2
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Citric Acid Cycle
Step 7– hydration reaction– fumarase is enzyme
C
CCH
OO-
C
H
OO-
fumarate
+ H2Ofumarase
CH2
CCH
OO-
C OO-
OH
malate
C
CCH
OO-
C
H
OO-
fumarate
+ H2Ofumarase
CH2
CCH
OO-
C OO-
OH
malate
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Citric Acid Cycle
Step 8– oxidation using NAD+
– product is oxaloacetate!
CH2
CCH
OO-
C OO-
OH
malate
malatedehydrogenase
CH2
CC
OO-
C OO-
O
oxaloacetateNADH NAD+
CH2
CCH
OO-
C OO-
OH
malate
malatedehydrogenase
CH2
CC
OO-
C OO-
O
oxaloacetateNADH NAD+
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.8, p.652
Electron (and H+) Transport
End products of the Citric Acid Cycle Reduced (or spent) Coenzymes
– NADH
– FADH2
Carry H+ and e- and yield energy when combining with oxygen:
4 H+ + 4 e- + O2 2 H2O4 H+ + 4 e- + O2 2 H2O
Electron (and H+) Transport
Many Enzymes are involved in ET Enzymes are imbedded in inner membrane of
the mitochondria Enzymes are in a particular sequence
– each accepts electrons– increasing affinity for electrons
Final acceptor of electrons is molecular O2 to make water O2
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Fig. 26.10, p.656
http://www.youtube.com/watch?v=xbJ0nbzt5Kw
http://www.youtube.com/watch?v=Idy2XAlZIVA
http://www.youtube.com/watch?v=A32CvcfA_K0&feature=PlayList&p=F09BC040A0B953F8&playnext=1&playnext_from=PL&index=10
http://www.youtube.com/watch?v=1engJR_XWVU
Electron Transport chain - youtube
Electron (and H+) Transport
Many Enzymes are involved in Oxidative Phosphorylation
2 H+ + 2 e- + 1/2 O2 H2O2 H+ + 2 e- + 1/2 O2 H2O
Flavo-protein
Lipid bilayerLipid bilayer
FeSprotein
Qenzyme
b
bc1 c a a3
ATPase
cytochromes
OO22
NADH NAD+ FADH2 FAD
ATPATP
2 H+ 2 H+ 2 H+
overall 2 ATP2 ATPproduced
overall 3 ATP3 ATPproduced
O2-
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
The Energy Yield from a C2
Each NADH produces 3 ATP Each FADH2 produces 2 ATP
(Each pair of H+ produces 1 ATP)
For each C2 unit (acetyl CoA) we produce...– 1 GTP directly (same as 1 ATP) from step 5 TCA
– 3 NADH in ET (3 x 3 = 9 ATP) Indirect
– 1 FADH2 in ET (1 x 2 = 2 ATP) Indirect
For a total of ..................... 12 ATP(and some waste CO2)
$
Indirect(from ET)
Conversion of ATP
How does the body utilize this Chemical Energy? Conversion to Other Forms
– biosynthesis Electrical Energy
– ion gradients (K+, Na+) Mechanical Energy
– muscle contraction Heat Energy
– maintain 37 oC or 98.6 oF
Muscle Contraction
Chemical Energy converted to Mechanical Energy:
Thick (myosin) and thin (actin) filaments Hydrolysis of ATP causes the interaction of the
filaments (muscle contraction)
contraction