Glycolysis &
Fermentation
7.1
ATP is the main energy currency of cells
Cellular respiration – process of making ATP by
breaking down organic compounds

A catabolic, exergonic, oxygen (O2) requiring
process that uses energy extracted from
macromolecules (glucose) to produce energy
(ATP) and water (H2O).
Cellular respiration equation:
C6H12O6 + 6O2  6CO2 + 6H2O + energy
glucose
ATP
byproduct
 Who
uses cellular respiration and
 Where does it take place?
Who undergoes cellular
respiration? (eukaryotes)


Plants - Autotrophs: self-producers.
Animals - Heterotrophs: consumers.
What are the Stages of
Cellular Respiration?
 Glycolysis
 The
Krebs Cycle
 The Electron Transport Chain
Where? Mitochondria

Organelle where cellular respiration takes place.
Outer
membrane
Inner
membrane
Inner
membrane space
Matrix
Cristae
Redox Reaction

Transfer of one or more electrons from one
reactant to another.

Two types:
1. Oxidation
2. Reduction
Oxidation Reaction

The loss of electrons from a substance.

Or the gain of oxygen.
Oxidation
C6H12O6 + 6O2 6CO2 + 6H2O + energy
glucose
ATP
Reduction Reaction
The gain of electrons to a substance.
 Or the loss of oxygen.

Reduction
C6H12O6 + 6O2 
6CO2 + 6H2O + energy
glucose
ATP
byproduct
Breakdown of Cellular Respiration
1. Glycolysis (splitting of sugar)
a. cytosol, just outside of
mitochondria.
2. Grooming Phase
a. migration from cytosol to matrix.
Breakdown of Cellular Respiration
3. Krebs Cycle (Citric Acid Cycle)
a. mitochondrial matrix
4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
a. Also called Chemiosmosis
b. inner mitochondrial membrane.
GLYCOLYSIS


biochemical pathway, yields 2 ATP
Occurs in cytosol

Converts NAD+ oxidized to NADH to produce
pyruvic acid then reduced to form lactic acid

With Oxygen > aerobic - additional ATP
Without Oxygen > anaerobic - fermentation
yields NO additional ATP

1. Glycolysis
A. Energy use Phase:
Glucose (6C)
2ATP
C-C-C-C-C-C
2 ATP - used
0 ATP - produced
0 NADH - produced
2ADP + P
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
C-C-C
C-C-C
1. Glycolysis
B. Energy Yielding Phase
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
4ADP + P
4ATP
GAP
GAP
C-C-C C-C-C
0 ATP - used
4 ATP - produced
2 NADH - produced
Pyruvate (2 - 3C)
(PYR)
C-C-C C-C-C
(PYR) (PYR)
1. Glycolysis

Total Net Yield
2 - 3C-Pyruvate (PYR)
2 - ATP (Substrate-level Phosphorylation)
2 - NADH
Substrate-Level Phosphorylation

ATP is formed when an enzyme transfers a
phosphate group from a substrate to ADP.
Enzyme
Example:
PEP to PYR
Substrate
(PEP)
Product
(Pyruvate)
OC=O
C-OCH2
OC=O
C=O
CH2
P
P
P
Adenosine
ADP
P P
P
Adenosine
ATP
Animation:

http://www.science.smith.edu/departments
/Biology/Bio231/glycolysis.html
RECALL

Redox – one reactant is oxidized while
another is reduced
oxidized loses e- and becomes pos
 reduced gains e- and becomes neg

GYLCOLYSIS RECAP
glucose oxidized yields pyruvic acid
 reactions take place in cytosol
 NAD+ to NADH (electron acceptor)
 Pyruvic acid yields 4 ATP but 2 used in
process (so net yield is 2 ATP)

Fermentation
fermentation is the formation of alcohol from
sugar.
 Occurs in cytosol when “NO Oxygen” is
present (called anaerobic).


Remember: glycolysis is part of
fermentation.

Two Types:
1. Lactic Acid (animal cells)
2. Alcohol (plant cells)
Lactic acid fermentation

NADH oxidized to NAD+
e.g. Yogurt, cheese
muscle – not enough oxygen so switch to
anaerobic respiration b/c oxygen is depleted
which makes cytosol acidic so produces
cramps
 *in
Lactic Acid Fermentation

Animals (pain in muscle after a workout).
C
C
C
C
C
C
Glucose
2ADP
+2 P
2ATP
2NADH
C
C
C
Glycolysis
2 NAD+
2NADH
2 Pyruvic
acid
2 NAD+
C
C
C
2 Lactic
acid
Lactic Acid Fermentation

End Products: Lactic acid fermentation
2 - ATP (phosphorylation)
2 - Lactic Acids
Alcoholic Fermentation

convert pyruvic to ethyl alcohol by
removing CO2
e.g. bread, beer, wine - need enzymes in
yeast
Alcohol Fermentation

Plants and Fungi
C
C
C
C
C
C
glucose
2ADP
+2 P
beer and wine
2ATP
2NADH
C
C
C
Glycolysis
2 NAD+

2NADH
2 Pyruvic
acid
2 NAD+
C
C
2 Ethanol
2CO2
released
Alcohol Fermentation

End Products:
2 - ATP (phosphorylation)
2 - CO2
2 - Ethanol’s

glycolysis is not efficient but unicellular
organisms don’t need much energy to
function
 E.g.

paramecium, ameoba
probably evolved early in history of life

kilocalories – 1 kcal = 1000 cal
How does the overall equation for
aerobic respiration relate to its four
stages?

http://w3.dwm.ks.edu.tw/bio/activelearner/
07/ch7intro.html
Aerobic Respiration
7.2
Aerobic respiration
cellular respiration that requires oxygen
 2 major stages: Krebs cycle & electron
transport chain

STAGE 1
Krebs cycle – biochemical pathway that
breaks down acetyl CoA producing CO2,
Hydrogen, & ATP
 Aka = Citric Acid Cycle
 Completes oxidation of glucose began in
glycolysis
 Takes place in/ mitochondrion unlike
glycolysis that occurs in/ cytosol


Pyruvic acid from glycolysis diffuses
across membrane to Mitochondrial
matrix & forms Acetyl coenzyme A
(acetyl CoA)
5 Steps in Krebs cycle
Step 1 – produces citric acid
 Step 2 – releases CO2
 Step 3 – releases CO2
 Step 4 – conversion of 4-carbon compound
 Step 5 – 4-carbon compound converted back
to oxaloacetic acid


Citric acid - formed when acetyl CoA
combines with Oxaloacetic acid

FAD - flavin adenine dinucleotide – like
NAD+ b/c accepts electrons

Each turn of citric acid cycle produces:
 ATP,
NADH, FADH2

In glycolysis: 1 glucose produced 2 ATP
which is same as Krebs cycle
Stage 2:
Electron transport chain – occurs along
inner membrane
 Concentration gradient between 2
membranes drive chain
 ATP synthase catalyzes ATP from ADP and
phosphate ion known as chemiosmosis just
like photosynthesis

Efficiency of energy:
glycolysis = 2 ATP
 Krebs =
2 ATP
 E.T.C. =
34 ATP
38 ATP

 but
some is used to pump NADH across
membrane so ~ 36 ATP
summary of Cellular Respiration:
http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookGlyc.html
References





http://www.search.com/reference/Mitochondrion
http://images.google.com/imgres?imgurl=http://microbewiki.kenyon.edu/images/thumb/2/25/Mitochondria.gif/400px
Mitochondria.gif&imgrefurl=http://microbewiki.kenyon.edu/index.php/Mitochondria&h=311&w=400&sz=94&hl=en&
start=107&um=1&tbnid=7oaJZwsF_GSTgM:&tbnh=96&tbnw=124&prev=/images%3Fq%3Dmitochondrial%2Bmatr
ix%26start%3D100%26ndsp%3D20%26svnum%3D10%26um%3D1%26hl%3Den%26rlz%3D1T4GGIC_enUS233
US233%26sa%3DN
http://images.google.com/imgres?imgurl=http://wps.prenhall.com/wps/media/objects/486/498525/FG06_12FR.JPG
&imgrefurl=http://wps.prenhall.com/esm_freeman_biosci_1/0,6452,498573,00.html&h=268&w=550&sz=41&hl=en&start=17&um=1&tbnid=OG0HGNN3_pgRmM:&tbnh=65&tbnw=133&prev=
/images%3Fq%3Dmitochondrial%2Bmatrix%26svnum%3D10%26um%3D1%26hl%3Den%26rlz%3D1T4GGIC_en
US233US233%26sa%3DG
http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookGlyc.html
www.biologyjunction.com