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Relay for Life!
April 12th at the OMAC!
6am-6pm
relayforlife.org/brown
Regrade Requests due
by 5 PM today
Week 6 Hmwk.
due Friday
Note: Week 6
Homework Hints!
Before class on Friday:
Watch the Movies!
Coming up Next Week: The Double Helix
Is this letter worth
One Million Dollars?
Meaning? Time to start reading “The
Double Helix” by J. D. Watson
Coming up Next Week: The Double Helix
Anabolism - pathways that
build up complex molecules
Catabolism - pathways that
break complex molecules down
Metabolism - the sum total of
chemical pathways in the cell
Glycolysis & the Krebs Cycle
Energy and the Cell
The Role of ATP
Glycolysis
Electron Carriers
Krebs Cycle
The Mitochondrion
C6H12O6 + 6O2
6CO2 +6H2O
∆G = - 686 kcal/mole
1) How to release energy slowly?
2) How to capture that energy and
distribute it throughout the cell?
ATP
Adenosine Triphosphate
Adenine
Phosphate groups
Ribose
The tri-phosphonucleotide
ATP is the cell’s primary
means of storing and
transferring small amounts
of chemical energy.
ATP + H2O
ADP + Pi
∆G = - 7 kcal/mole (approx.)
Question: “I thought energy was relesed when
bonds were formed, not when they are broken!”
Answer: That’s still true. Look at the whole picture!
Broken: (1) P—O bond, (1) H—O bond
Formed: (1) P—O bond, (1) H—O bond
ATP + H2O
ADP + Pi
∆G = - 7 kcal/mole (approx.)
ATP
ADP
Energy
Adenosine diphosphate + Phosphate
ATP + H2O
Energy
Adenosine triphosphate (ATP)
ADP + Pi
∆G = - 7 kcal/mole
ATP provides chemical
energy for a wide
variety of chemical
processes (ion
transport, internal
movement, chemical
signaling, & molecular
synthesis)
An overview of Cellular Respiration
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Cytoplasm
C6H12O6 + 6O2
Mitochondrion
Electrons
carried in
NADH and
Krebs FADH2
Cycle
Electron
Transport Chain
Mitochondrion
6CO2 +6H2O
GLYCOLYSIS
“Sugar-Breaking”
Glycolysis is a pathway in the cytoplasm of all cells.
Glucose (C6) enters the pathway.
Two molecules of pyruvate (C3) leave glycolysis.
Summary of Glycolysis:
glucose
2ATP
2NAD+
4ATP
2NADH
pyruvate
2 ATPs used to start
pathway.
4 ATPs produced
(net gain: 2)
2 molecules of NAD+
converted to 2 of NADH
NAD+
A soluble, highenergy electron
acceptor.
It can accept,
hold, and
transfer 2 highenergy
electrons.
eNAD+
e-
H+
NADH
H+
H+
2 ATP (net) = 14 kCal
Glucose (total) = 686 kCal
At the end of Glycolysis: How are we doing in
terms of energy captured in the form of ATP?
So far, we have released (captured) very little
energy (2 ATPs ~ 14 kcal) . . . . And we have not
used any oxygen. What’s missing?
The
mitochondrion
An overview of Cellular Respiration
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Cytoplasm
C6H12O6 + 6O2
Mitochondrion
Electrons
carried in
NADH and
Krebs FADH2
Cycle
Electron
Transport Chain
Mitochondrion
6CO2 +6H2O
Pyruvate, the final product of
glycolysis, enters the
mitochondrion through a
transport protein....
... and is converted to
Acetyl Coenzyme A.
Summing Up: What does the Krebs Cycle
Accomplish?
2 pyruvates enter Cycle
6 CO2 released
2 ATPs (+2 from Glycolysis)
+ high-energy electrons
passed to carrier
molecules:
8 NADH (+2 from Glycolysis)
2 FADH2
Four unsolved mysteries
1) What happens to those reduced electron carriers?
2) How do we make enough ATP to make this
worthwhile?
3) Why do we need oxygen? (it hasn't been used yet!)
4) Why is Krebs cycle located in the mitochondrion?