To provide the energy for nearly all life
processes (such as synthesizing biomolecules, active transport, cell division,
movement, etc.)
The energy comes from foods
such as glucose, and prior to that, from the sun for photosynthesis.
6CO2 + 12H2O + solar energy --> C6H12O6 + 6O2 + 6H2O
C6H12O6 + 6O2 + 2ATP --> 38ATP + 6CO2 + 6H2O
They are linked as a cycle.
The products of one reaction are the reactants of the other.
What is ATP?????
A modified ribonucleotide
Glucose - consumed as food and digested, brought to cells by blood
Oxygen - inhaled into the lungs, brought to cells by hemoglobin in blood
ATP - 2 energy molecules already available in the cells
To generate ATP
Anaerobic respiration and fermentation
Phosphorylation
C6H12O6 + 6O2 + 2ATP --> 38ATP + 6CO2 + 6H2O
If all the energy in glucose were released at once, it would be wasted.
Most of the energy would be lost all at once as heat, burning up the cell.
Glycolysis
Krebs cycle
Electron transport chain
Cytoplasm
Mitochondria
The matrix of the mitochondria
The cristae of the inner membrane of the mitochondria
Glycolysis
Glyco = sugar lysis = to split or break
- Occurs in the cytoplasm
- Does not require oxygen
Input:
1 glucose
2 ATP
Output:
2 pyruvate
2 NADH
4 ATP
Substrate-Level Phosphorylation
- ATP generated during glycolysis
is formed by substrate-level
phosphorylation
- A high energy "donor" molecule
directly transfers a phosphate
group to ADP, forming ATP
- Usually occurs with the help of
an enzyme
- Does not require an H+ gradient
or ATP Synthase
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/ animation
__how_glycolysis_works.html
Oxidation of Pyruvate
- If oxygen is present, pyruvate
will continue to be broken down
- Before pyruvate can enter the
Krebs Cycle, it is oxidized into
acetyl CoA
Oxidation of Pyruvate
- Pyruvate loses a carbon
(leaves as CO2)
- The broken bond is used to
reduce NAD+ to NADH
(charges up the molecule with two
high energy electrons)
- The remaining two carbons from
the pyruvate bond to coenzyme A
creating acetyl CoA
- This happens to each pyruvate
Simple Oxidation of Pyruvate and Krebs Cycle
Krebs Cycle
(aka Citric Acid Cycle)
Input:
2 acetyl CoA
Output:
4 CO2
2 ATP
6 NADH
2 FADH2
http://highered.mcgrawhill.com/sites/0072507470/student _view0/c
hapter25/animation__how _the_krebs_cycle
_works__quiz_1 _.html
Simple Oxidation of Pyruvate and Krebs Cycle
Electron Transport Chain
Input:
10 NADH
2 FADH2
6 O2
Output:
32 ATP
6 H2O
Electron Transport Chain
INTERMEMBRANE SPACE
H+
H+
H+
FADH2
ADP + Pi
NAD
2e- + O + 2H+
--> H2O
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__electron_transport_system _and_atp_synthesis__qu
iz_2_.html
http://vcell.ndsu.edu/animations/etc/movie-flash.htm
C6H12O6 + 6O2 + 2ATP --> 38ATP + 6CO2 + 6H2O
Glycolysis - cytoplasm
Oxidation of pyruvate - mitochondrial matrix
Kreb's Cycle - mitochondrial matrix
Electron Transport Chain - cristae of mitochondrial inner membrane
Glycolysis
Glucose
2 ATP
2 NADH
4 ATP
2 Pyruvate
2 CO2 exit as by-product and 2 NADH are produced
Kreb's Cycle
CoA
Oxaloacetate
Citrate
NADH
NAD+
NAD+
CO2
NADH
H2O
FADH2
NAD+
FAD2+
NADH
ATP
CO2
ADP + Pi
Electron Transport Chain
NADH
FADH2
2e- + O + 2H+
Outer membrane
Inner membrane
H+
ATP Synthase
ATP
Chemiosmotic
The set of reactions that require oxygen to break down
pyruvate to generate ATP
The fluid and space inside the inner membrane of the
mitochondrion
The biochemical pathway that breaks down 2 acetyl CoA to
produce 4CO2, 2ATP, 6NADH, and 2FADH2
flavine adenine dinucleotide; a molecule that accepts electrons
during redox reactions; FAD is the oxidized form
B
C
A
D
C
NADH; 3 NADH are produced in each turn making a total of 6 per glucose
The electron transport chain reactions
C6H12O6 + 6O2 + 2ATP --> 38ATP + 6CO2 + 6H2O
The folding of the inner membrane provides a large surface area for the
molecules of the electron transport chain.
The area between the inner and outer membranes provides a confined
space in which protons can accumulate, driving chemiosmosis.
Electron Transport Chain
INTERMEMBRANE SPACE
H+
H+
H+
FADH2
ADP + Pi
NAD
2e- + O + 2H+
--> H2O