Download Cellular Respiration

Cellular Respiration
Honors Biology
What is Cellular Respiration?
The process of converting food energy
into ATP energy
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 36 ATP
Why are both Photosynthesis and Cell
Respiration important to Ecosystems?
Light is the ultimate
source of energy for all
ecosystems
Chemicals cycle and
Energy flows
Photosynthesis and
cellular respiration are
opposite reactions
Why do plants need both
chloroplasts and mitochondria?
Chloroplasts use
energy from the
sun to make
glucose
Mitochondria
convert glucose to
ATP—the energy
currency of the cell
Why use ATP energy and not
energy from glucose?
Breaking down glucose yields too much energy
for cellular reactions and most of the energy
would be wasted as heat.
1 Glucose = 686 kcal
1 ATP = 7.3 kcal
1 Glucose → 36 ATP
How efficient are cells at converting glucose into
ATP?
– 38% of the energy from glucose yields ATP,
therefore 62% wasted as heat.
Cellular Respiration is a Redox Reaction
(Oxidation)
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
(Reduction)
Oxidation is the loss of electrons or H+
Reduction is the gain of electrons or H+
Cellular Respiration is a Redox Reaction
Glucose is oxidized when electrons and H+ are
passed to coenzymes NAD+ and FAD before
reducing or passing them to oxygen.
Glucose is oxidized by a series of smaller steps
so that smaller packets of energy are released
to make ATP, rather than one large explosion
of energy.
Cell Respiration can be divided into 3 Parts:
1) Glycolysis
2) The Krebs Cycle
3) The Electron Transport Chain
Where do the 3 parts of Cellular
Respiration take place?
Glycolysis:
– Cytosol
The Krebs Cycle:
– Matrix
Electron Transport
Chain and
Cheimiosmotic
Phosphorylation:
– Cristae
Parts of the Mitochondria
Anaerobic Respiration (no oxygen required, cytoplasm)
Glycolysis
(substrate level)
Glucose
2 ATP

4 ATP (Net 2 ATP)
2 NADH
2 Pyruvate
Aerobic Respiration (oxygen required, mitochondria)
Oxidation
Of
Pyruvate
2 Pyruvate

2 CO2
2 NADH
2 Acetyl CoA
Krebs Cycle
(substrate level)
2 Acetyl CoA

4 CO2
2 ATP
6 NADH
2 FADH2
Electron
Transport
Chain
(chemiosmotic)
10 NADH
2 FADH2
6 O2

32 ATP
6 H 2O
Total ATP Production in Cellular Respiration: 36 ATP produced
Glycolysis
Glucose
2 ATP
2 NAD+

2 Pyruvate
4 ATP (Net 2 ATP)
2 NADH
Glucose (C6) is split to make
2 Pyruvates (C3)
– 1st: ATP energy used to
phosphorylate glucose (stored
energy)
– 2nd: phosphorylated glucose
broken down into two C3 sugar
phosphates
– 3rd: the sugar phosphates are
oxidized to yield electrons and
H+ ions which are donated to
2NAD+ → 2NADH
– 4th: The energy from oxidation is
used to make 4 ATP molecules
(net 2 ATP)
Glycolysis
Glucose
2 ATP
2 NAD+

2 Pyruvate
4 ATP (Net 2 ATP)
2 NADH
Glucose (C6) is split to make
2 Pyruvates (C3)
An enzyme transfers
phosphate to ADP making
ATP
Glycolysis produces very
little ATP energy, most
energy is still stored in
Pyruvate molecules.
Oxidation of Pyruvate /Transition Reaction
(After glycolysis, before the Krebs Cycle)
2 Pyruvate
2 NAD+

2 CO2
2 NADH
2 Acetyl CoA
When Oxygen is present,
2 Pyruvates go to the
matrix where they are
converted into 2 Acetyl
CoA (C2).
2CO2 are released while
the 2 pyruvate get
converted
2 NADH’s carry electrons
and hydrogens to the
Electron Transport Chain
Coenzyme A assists the
process of creating
Acetyl CoA
The Krebs Cycle / Citric Acid Cycle
2
2
6
2
Acetyl CoA
ADP
NAD+
FAD

4 CO2
2 ATP
6 NADH
2 FADH2
Overview
-
Two Turns of the Krebs Cycle are
required to break down both
Acetyl Coenzyme A molecules.
-
Break down and oxidize each Acetyl
Co (2-C’s) to release 2 CO2 and yield
electrons and H+ ions to
-
3 NAD+ + 1 FAD → 3NADH + 1FADH2.
This yields energy to produce 1 ATP
(in each turn of the cycle)
The Krebs Cycle / Citric Acid Cycle
2
2
6
2
Acetyl CoA
ADP
NAD+
FAD

4 CO2
2 ATP
6 NADH
2 FADH2
Steps in Matrix of Mitochondria
- Oxaloacetate (4C) combines with Acetyl
CoA (2C) to form Citric Acid (6C)
- NAD+ and FAD molecules are reduced
as they pick up electrons and hydrogens
- An enzyme combines a phosphate group
with ADP to form ATP
- After CO2, NADH, FADH2, and ATP is
released, Oxaloacetate is recycled back
into the cycle to combine with another
Acetyl CoA
- **Remember the cycle occurs twice!
(once for each Acetyl CoA molecule) **
Produces some chemical energy in the
form of ATP but most of the chemical
energy is in the form of NADH and
FADH2 which then go on to the Electron
Transport Chain.
The Electron Transport Chain
10 NADH
2 FADH2
Oxygen

32 ATP
H2O
NADH and FADH2 (carrying
hydrogens and electrons)
go to the Electron
Transport Chain.
NADH and FADH2 release
electrons to
carriers/proteins
embedded in the
membrane of the cristae.
As the electrons are
transferred, H+ ions are
pumped from the matrix
to the intermembrane
space up the concentration
gradient.
http://vcell.ndsu.nodak.edu/animations/etc/movie.htm
The Electron Transport Chain
10 NADH
2 FADH2
Oxygen

32 ATP
H2O
Electrons are passed along
a series of 9 carriers until
they are ultimately
donated to an Oxygen
molecule.
½ O2 + 2 electrons + 2 H+
(from NADH and FADH2)
→ H2O.
The high H+ concentration
in the inner membrane
space creates a gradient
and is used to produce
ATP
http://vcell.ndsu.nodak.edu/animations/etc/movie.htm
ATP Synthase
– The H+ in the
intermembrane space
have a high concentration
– So they move back across
the inner mitochondrial
membrane and into the
matrix through a molecule
called ATP Synthase
– As ATP Synthase turns
and H+ ions pass
through, it changes shape
and the enzyme makes
ATP
Review ATP Production:
1) Glycolysis → 2 ATP
2) Oxidation of Pyruvate → No ATP
3) The Krebs Cycle → 2 ATP
4) The Electron Transport Chain
- Each NADH produces 2-3 ATP
so
10 NADH → 28 ATP
- Each FADH2 produces 2 ATP
so
2 FADH2 → 4 ATP
Total = 36 ATP
Review ATP Production:
1 Glucose = 686 kcal
1 ATP = 7.3 kcal
1 Glucose → 36 ATP
How efficient are cells at
converting glucose into ATP?
– 38% of the energy from
glucose yields ATP, therefore
62% wasted as heat (used to
maintain body temperature or
is dissipated)
– Ex. Most efficient Cars: only
25% of the energy from
gasoline is used to move the
car, 75% heat.
All Types of Molecules can be used
to form ATP by Cell Respiration:
Proteins, Carbohydrates, and Lipids must first
be broken down into their monomers and
absorbed in the small intestine.
Monomers may be further broken down into
intermediate molecules before entering
different parts of Cell respiration to ultimately
form ATP.
Anaerobic Respiration: Fermentation
If there is NO oxygen, then cells can make ATP
by Fermentation
Without oxygen, The Krebs Cycle and the
Electron Transport Chain do not operate, but
glycolysis still occurs.
Glucose
→
Pyruvate
NAD+ Glycolysis 2 NADH
2 ATP
→
Reduction Rxn
Lactate
or
Alcohol + CO2
Anaerobic Respiration: Fermentation
Fermentation yields a net gain of 2 ATP for every 1 Glucose.
(Inefficient)
Two Forms of Fermentation:
Lactic Acid Fermentation (animals)
Alcohol Fermentation (yeast and some bacteria)
WITHOUT O2
PYRUVIC ACID ___________
OXYGEN
ANAEROBIC
2 kinds of fermentation
Alcoholic
&
Lactic acid
ALCOHOLIC FERMENTATION
PYRUVIC
ACID +
+
ALCOHOL
CO
NAD
→
+
2+
Happens when yeast makes bread dough rise
air spaces in bread
CO2 bubbles make _____________
evaporates
Alcohol _______________
during cooking
http://www.deliciousdelicious.com/archives/herb%20bread%201.jpg
ALCOHOLIC FERMENTATION
PYRUVIC
ACID +
→ALCOHOL
+
CO2
+
NAD+
Happens when
beer
yeast
___________
make _______
or
bacteria
wine
____________
make ______
http://www.firstpath.com/images/alcohol.jpg
LACTIC ACID FERMENTATION
PYRUVIC
ACID +
→ LACTIC ACID
+
NAD+
muscles
Happens in _____________
during
____________when
body
exercise
can’t get oxygen to tissues
fast enough.
Lactic acid builds up in
muscles causing soreness
http://www.miranda.com/library.en/Images/Pictures/girls-runners.jpg
LACTIC ACID FERMENTATION
PYRUVIC
ACID +
→ LACTIC ACID
Happens when bacteria are used
to make foods and beverages
like:
__________________________
yogurt, cheese, buttermilk,
__________________________
& sour cream, pickles,
__________________________
saurkraut, and kimchi
+
NAD+
http://chronicle.augusta.com/images/headlines/032200/DANNON_YOGURT.jpg
http://www.reillydairy.com/natural_cheese.html
WHY DO FERMENTATION?
WHY NOT JUST KEEP MAKING ATP USING
GLYCOLYSIS?
WITHOUT OXYGEN,
PYRUVIC ACID
builds up
___________
and all the
NAD+ carriers get full.
_______
Eventually glycolysis will
NAD+
PYRUVIC
ACID +
→ALCOHOL
+
CO2
LACTIC ACID
+
NAD+
NAD+
______
You get the NAD+ carriers back
FERMENTATION HAPPENS so cells
+
REGENERATE
the
NAD
can ____________________
needed to keep glycolysis going