HANGRY AND NO ENERGY!!
Cellular
Respiration
HOW CELLS HARVEST CHEMICAL ENERGY
Cellular Respiration – General
Concepts
1. Equation: C6H12O6 (Glucose) + 602  6CO2 + 6H20
+
ATP
2. A CATABOLIC pathway

Oxygen is consumed as a reactant along with organic compounds

Involves three stages:
1. Glycolysis
2. Krebs Cycle
3. Electron Transport Chain
Where?
Who?
What?
What Is ATP?
1. Adenosine
Triphosphate
2. Energy “currency”
of the cell
3. Organic molecule
containing highenergy Phosphate
bonds
What Does ATP Do for You?
 It
supplies YOU with
ENERGY!
How Do We Get Energy
From ATP?
1. By breaking the
high- energy bonds
between the last
two phosphates
2. HYDROLYSIS
RXN
3. Results in
production of ADP
NADH and FADH2 –
Electron “Taxis"
1. NAD+ traps
electrons from
glucose to make
NADH (energy
stored)
2. Similarly, FAD+
stores energy as
FADH2
Oxidized
Nicotinamide
adenine dinucleotide
Reduced
Where Does Cellular
Respiration Take Place?

Takes place in two parts of the cell:
1. Glycolysis occurs in the Cytoplasm
2. Krebs Cycle & ETC take place in the
Mitochondria
Step 1: Glycolysis
Step 1: Glycolysis
1. Means “splitting of sugar”
2. Where? Cytoplasm
3. Splits glucose (6C) into two pyruvate
(3C) molecules
4. Occurs whether or not oxygen is present
= ANAEROBIC
Step 1: Glycolysis
5. EXERGONIC
PROCESS = Energy is
released

Most of the energy
harnessed is
conserved in the highenergy electrons of
NADH and in the
phosphate bonds of
ATP
Glycolysis Summary
1. Takes place in the Cytoplasm
2. Anaerobic (Doesn’t Use Oxygen)
3. Requires input of 2 ATP
4. Glucose splits into 2 molecules of
Pyruvate
5. Produces 2 NADH and 4 ATP = NET 2
ATP
Formation of Acetyl CoA
1. Junction between Glycolysis
and Krebs cycle
2. Oxidation of pyruvate to
acetyl CoA
3. Pyruvate is moved from the
cytosol into the mitochondrion by
a carrier proteins
4. CO2 is removed from pyruvate
– making a 2C compound
5. Coenzyme A is attached to the
acetyl group
Step 2: Krebs Cycle
1. Requires Oxygen (Aerobic)
2. Cyclical series of oxidation
reactions that give off CO2
and produce 1 ATP per cycle
3. Turns twice per glucose
molecule
4. Produces 2 ATP TOTAL
5. Takes place in MATRIX of
mitochondria
Krebs Cycle Summary
1. EACH turn of the Krebs Cycle also produces:
3NADH
1FADH2
2CO2
2. For EACH Glucose molecule, the Krebs Cycle
produces:
6NADH
2FADH2
4CO2
2ATP
Step 3: Electron Transport
Chain
1. Located in the inner membrane
of the mitochondria.
2. Oxygen pulls the electrons from
NADH and FADH2 “taxis”
down the electron transport
chain to a lower energy state
.
3. Ultimately produces ~34 ATP =
BIGGEST “BANG FOR YOUR
BUCK”
Step 3: Electron Transport
Chain
4. Requires oxygen = final electron acceptor
5. For EACH FADH2 molecule – 2 ATP’s are produced
6. For EACH NADH molecule – 3 ATP’s are produced.
7. CHEMIOSMOSIS – the production of ATP using the
energy of H+ gradients across membranes to
phosphorylate ADP
ATP Synthase and
Chemiosmosis
1. An enzyme in the inner membrane in the
mitochondria.
2. It allows H+ to pass through the membrane and uses
the free energy difference to phosphorylate ADP
3. For EACH H+ ion that flows through ATP synthase,
one ATP can be formed from ADP
Cellular Respiration in
Summary
1. Glycolysis
2 ATP
2 NADH
2 Pyruvate
**Formation of Acetyl CoA**
2. Kreb’s Cycle
6NADH
2FADH2
4CO2
2ATP
3. ETC and Chemiosmosis
~34 ATP
Grand Total: 38 ATP