Download Cellular Respiration

Use your dominant hand
 Open and close the pin (with your
thumb and forefinger) as many times as
you can for 20 seconds while holding the
other fingers straight out!
 Repeat for 5 more continuous trials!
 Repeat for the non-dominant hand

What happened as time went on?
 How did you hands feel at the end?
 Was there a difference in dom and nondom hands?
 Why will your muscles recover in about
10 min?

The total amount of energy in the
universe is constant!
 Energy cannot be created or destroyed
but only converted to one form into
another!
 Activation Energy – Amount of E required
to break chemical bonds

Entropy = Randomness and Chaos
 Universe favours Entropy – think of how
messy your room gets!
 In all Rxns – Energy and Entropy are
needed!
 Spontaneous Human Combustion?

Energy of products more than reactants
 Photosynthesis
 Light energy converted to stored
chemical energy C6H12O6
 Every molecule of glucose contains
2870kJ

Photosynthesis
Energy of products is less than reactants
 Free energy is released!
 Cellular respiration
 The energy from glucose is released and
harnessed into ATP at a controlled rate!

Cellular Respiration
The Goal of C.R. is to create ATP from
Glucose!
 See handout!
 Four main parts...
1) Glycolysis
2) Pyruvate Oxidation
3) Krebs Cycle (Citric Acid Cycle)
4) Electron Transport Chain

Redox Reactions
 Substrate Level Phosphorylation
 Oxidative Phosphorylation


These rxns occur frequently throughout
the cellular respiration pathways!





Energy metabolism in cells involves oxidation
reactions.
Oxidation involves the transfer of an electron
from a molecule, which is said to be oxidized,
to another molecule, which is said to be
reduced.
An oxidation cannot occur without a
corresponding reduction. They are PAIRED
reactions.
Many important redox reactions in cells require
the presence of coenzymes.
The redox reactions of cellular respiration
commonly involve the following coenzymes:
1) NAD: Nicotinamide adenine
dinucleotide
NAD+ + 2 e- + 2 H+ → NADH + H+
*the second H+ dissolves into cytosol
2) FAD: Flavin adenine dinucleotide
FAD + 2e- + 2 H+ → FADH2
*

LEO the lion says GER
 Lose
 Electrons
 Oxidized!
SAYS...
 Gain
 Electrons
 Reduced!

“Reduced” means that the overall
positive charge of the molecule has
decreased (due to accepting the
electons!)

A mechanism forming ATP directly in an
enzyme-catalyzed reaction
ATPase
ADP + Pi + 31 kJ/mole
ATP
 This is called Phosphorylation... The
opposites is called Dephosphorylation
 A single muscle cell uses 600 million ATP per
minute
 The body consumes its own mass in ATP per
day via constant recycling!

ATP formed in-directly
 Uses redox rxns (see previous slides)
 NADH
 FADH2
 These molecules harvest energy and
transfer it to ATP by the end of Cellular
Resp.

A glucose is broken down into 2 Pyruvate
molecules
 Brief overview...
 http://highered.mcgrawhill.com/sites/0072507470/student_view0/
chapter25/animation__how_glycolysis_w
orks.html
 Occurs in the cytoplasm
 Anaerobic (doesn’t need oxygen!)
 See handout!!

glucose
Glycolysis
ATP
Hexokinase
ADP
glucose-6-phosphate
Phosphoglucose Isomerase
fructose-6-phosphate
ATP
Phosphofructokinase
ADP
fructose-1,6-bisphosphate
Aldolase
glyceraldehyde-3-phosphate + dihydroxyacetone-phosphate
Triosephosphate
Isomerase
Glycolysis continued
glyceraldehyde-3-phosphate
NAD+ + Pi
Glyceraldehyde-3-phosphate
Dehydrogenase
NADH + H+
Glycolysis
cont.
Recall
that there
are 2
GAP per
glucose.
1,3-bisphosphoglycerate
ADP
Phosphoglycerate Kinase
ATP
3-phosphoglycerate
Phosphoglycerate Mutase
2-phosphoglycerate
Enolase
H2O
phosphoenolpyruvate
ADP
Pyruvate Kinase
ATP
pyruvate
Balance sheet for ~P bonds of ATP:

2
How many ATP ~P bonds expended? ________

How many ~P bonds of ATP produced?
(Remember there are two 3C fragments from
4
glucose.) ________

Net production of ~P bonds of ATP per glucose:
2
________
Glucose + 2 ADP + 2 Pi + 2 NAD+
2 Pyruvate + 2 ATP + 2 (NADH + H+)
2.2% of E from glucose is transferred to
ATP via Glycolysis.
 This might be good enough for some
micro-organisms but not larger species
like ourselves!
 A much more detailed look...
http://www.youtube.com/watch?v=O5eM
W4b29rg&feature=related
 Page 115 #1-7

Occurs in the Matrix
 See P 100 for a great diagram
 General Equation...
 CoA = coenzyme A

2 Pyruvate + 2 NAD+ + 2 CoA
2 acetylCoA + 2 NADH + 2H+ +2CO2
Acetyl CoA then enters the Kreb Cycle!!
In mitochondrion
 Mostly on inner membrane
 Many enzymes, coenzymes and other
molecules are in an organize pattern on
the inner membrane.
 Brief Overview...
http://highered.mcgrawhill.com/sites/0072507470/student_view0/
chapter25/animation__how_the_krebs_c
ycle_works__quiz_1_.html

More depth!
 http://www.youtube.com/watch?v=A1D
jTM1qnPM
 Note where H2O is used and CO2 is
released!

By the end of the Krebs Cycle (thru Steps 13) the entire glucose molecule is
consumed.
 6C get converted to 6 CO2 along the way!


HARNESSED ENERGY (NET)!
› 4 ATP (2 Glycolysis, 2 Krebs)
› 12 reduced coenzymes:
 2 NADH (Glycolysis)
 2 NADH (Pyruvate Oxidation stage)
 6 NADH (Krebs)
 2FADH2 (Krebs)
Occurs on the inner membrane of mito
 Transports electrons (from NADH and
FADH2) thru a series of redox rxns that
release free energy.
 This free energy is used to pump H+
protons into the inner membrane space
of the mitochondria
 This creates an electro-chemical
gradient that is a source of free energy
which is used to create ATP!

Overheads
 Visuals...
 http://highered.mcgrawhill.com/sites/0072507470/student_view0/
chapter25/animation__electron_transpor
t_system_and_atp_synthesis__quiz_1_.ht
ml
 http://www.youtube.com/watch?v=0Lc
WbKOW0u8&feature=related

Oxygen is the final acceptor of electrons
that pass thru the ETC!!
 Its high electronegativity pulls the
electrons through the ETC
 Electrons fall (like a skydiver)...this energy
pumps H+ ions into the inner membrane
space so they can “fall” back into the
matrix and make ATP!

Protons move through a
Proton Channel and
ATP synthase to
produce ATP molecules
 Oxidative
Phosphorylation!!
 Electrochemical
Gradient must be
maintained (by eating!)
or ATP production stops!

NADH diffuses thru the inner membrane
via the glycerol-phosphate shuttle (P105)
 NADH passes electrons to FAD to make
FADH2
 NADH can also pass electrons to NAD+ in
the matix via the aspartate shuttle (less
common!)

In simplified terms NADH pumps 3 H+ ions
across...therefore creating 3 ATP
molecules!
 FADH2 enters the ETC at Q...therefore
only pumping 2 H+ ions across and
making 2 ATP molecules!

Theoretical and Actual Yields
 Actual...depends on environment (ie
temp)
 Theoretical – 36 ATP
 Actual yield is less...heat loss, H+ ions
leaking...Approx 30 ATP??
 Aerobic C.R. Is approx 32% efficient

See page 110 and page 114
 To review all 4 Steps...See these
interactive animations...
 http://www.science.smith.edu/departm
ents/Biology/Bio231/


Page 115 - #8-18

An organism’s Metabolic rate is the
amount of energy consumed at a given
time and a measure of the overall rate of
C.R. Rxns!
Phosphofructokinase (catalyzes step 3 of
Glycolysis) controls C.R.
 It is activated by ADP and inhibited by
ATP
 NADH inhibits pyruvate decarboxylase
and prevents Acetyl-CoA from forming
 An organism’s Metabolic Rate is the
amount of energy consumed by an
organism in a given time.

PRO’s Broken down into individual A.A.’s
in the body.
 First stage of this is deamination (removal
of amino group as ammonia NH3), a
waste.
 The remaining parts of the A.A.’s are
converted into components of glycolysis
or Krebs cycle

Triglycerides are digested into glycerol
and fatty acids
 Glycerol can be converted into glucose
by gluconeogenesis or into DHAP
 Fatty Acids are transported to the matrix,
undergo beta-oxidation (conversion into
acetyl CoA...enters the Kreb cycle)




Occurs during vigorous
exercise when O2 is in
short supply. Very
inefficient…but quick!
After glycolysis, the
pyruvic acid is
converted into lactic
acid.
L.A. is toxic and must
be removed by
delivering O2 to the
cells…this is why you
suck wind after a
sprint!!!
Elite athletes can
tolerate higher L.A.
levels in their blood.
 Eg. Lance
Armstrong 4x the
normal threshold!
 This process is also
used to make
cheese and
yogurt…bacteria
do the work!


Can be increased by
training
A measure of aerobic fitness
 Maximum volume of oxygen (mL) that
the cells can remove from the
bloodstream in one minute per kg of
body weight.
 35 mL/kg/min is average
 A very painful test....run/bike faster and
faster!

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

Can be improved
with training
Genetics!
Decreases with age
http://www.youtube.
com/watch?v=FSL1jk
wmWcs
Occurs in
cytoplasm of yeast
cells.
 After glycolysis,
pyruvic acid is
converted to CO2
and alcohol.
 Ethanol could be a
valuable, clean
burning fuel for
industry and
transportation.


Overheads
The energy that
fuels life on earth
cycles between
P.S. and C.R.
 The products of
each process
become the
substrates for the
other.
 HW Page 124
 #1-12


http://walking.ab
out.com/library/c
al/ucrockport.htm