Cellular Respiration

1
Cellular Respiration

• Giving you the energy you need!

2
Clothespin Challenge!

• 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

3
Clothespin Challenge!

• What happened as time went on?
• How did you hands feel at the end?
• Was there a difference in dom and non-dom hands?
• Why will your muscles recover in about 10 min?

4
METABOLISM BASICS
5
1st Law of Thermodynamics

• 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

6
2nd Law of Thermodynamics

• 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?

7
ENDERGONIC REACTIONS

• Energy of products more than reactants
• Photosynthesis
• Light energy converted to stored chemical energy
  C6H12O6
• Every molecule of glucose contains 2870kJ

8

• Photosynthesis

9
EXERGONIC REACTIONS

• 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!

10

• Cellular Respiration

11
Cellular Respiration Overview

• The Goal of C.R. is to create ATP from Glucose!
• See handout!
• Four main parts...
• Glycolysis
• Pyruvate Oxidation
• Krebs Cycle (Citric Acid Cycle)
• Electron Transport Chain

12
(No Transcript)
13
Important Reactions!

• Redox Reactions
• Substrate Level Phosphorylation
• Oxidative Phosphorylation
• These rxns occur frequently throughout the
  cellular respiration pathways!

14
Redox Reactions

• 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

15
Redox Rxns Make Energy Carriers

• 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

16
A Memory Trick!

• LEO the lion says GER
• Lose
• Electrons
• Oxidized!
• SAYS...
• Gain
• Electrons
• Reduced!

17

• Reduced means that the overall positive charge
  of the molecule has decreased (due to accepting
  the electons!)

18
Substrate Level Phosphorylation

• 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!
  

19
(No Transcript)
20
Oxidative Phosphorylation

• 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.

21
STEP 1 - Glycolysis

• A glucose is broken down into 2 Pyruvate
  molecules
• Brief overview...
• http//highered.mcgraw-hill.com/sites/0072507470/s
  tudent_view0/chapter25/animation__how_glycolysis_w
  orks.html
• Occurs in the cytoplasm
• Anaerobic (doesnt need oxygen!)
• See handout!!

22
(No Transcript)
23
(No Transcript)
24
Glycolysis cont. Recall that there are 2 GAP per
glucose.
25
Glycolysis

• Balance sheet for P bonds of ATP
• How many ATP P bonds expended? ________
• How many P bonds of ATP produced? (Remember
  there are two 3C fragments from glucose.)
  ________
• Net production of P bonds of ATP per glucose
  ________

2
4
2
26
Overall Equation

• Glucose 2 ADP 2 Pi 2 NAD
• 2 Pyruvate 2 ATP 2 (NADH
  H)

27
Is Glycolysis Efficient?

• 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?vO5eMW4b29rgfeature
  related
• Page 115 1-7

28
Mitochondrion Anatomy
29
STEP 2 -Pyruvate Oxidation

• 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!!

30
STEP 3 - Krebs 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.mcgraw-hill.com/sites/0072507470/s
  tudent_view0/chapter25/animation__how_the_krebs_cy
  cle_works__quiz_1_.html

31
Krebs Cycle

• More depth!
• http//www.youtube.com/watch?vA1DjTM1qnPM
• Note where H2O is used and CO2 is released!

32
The Balance Sheet so far...

• By the end of the Krebs Cycle (thru Steps 1-3)
  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)

33
(No Transcript)
34
STEP 4 The Electron Transport Chain
35
ETC Details...

• 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!

36
The Key Structures...
37
ETC

• Overheads
• Visuals...
• http//highered.mcgraw-hill.com/sites/0072507470/s
  tudent_view0/chapter25/animation__electron_transpo
  rt_system_and_atp_synthesis__quiz_1_.html
• http//www.youtube.com/watch?v0LcWbKOW0u8feature
  related

38
The Importance of Oxygen

• 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!

39
Chemiosmosis

• 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!

40
Protons (indicated by charge) enter back into
the mitochondrial matrix through channels in ATP
synthase enzyme complex. This entry is coupled to
ATP synthesis from ADP and phosphate (Pi)
41
What happens to the NADH from Glycolysis?

• 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!)

42
NADH vs. FADH2

• 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!

43
Aerobic Respiration Efficiency

• 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

44
Final Balance Sheet

• See page 110 and page 114
• To review all 4 Steps...See these interactive
  animations...
• http//www.science.smith.edu/departments/Biology/B
  io231/
• Page 115 - 8-18

45
Metabolic Rate

• An organisms Metabolic rate is the amount of
  energy consumed at a given time and a measure of
  the overall rate of C.R. Rxns!

46
Control Mechanisms (p 113)

• 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 organisms Metabolic Rate is the amount of
  energy consumed by an organism in a given time.

47
Related Pathways
48
Protein Catabolism

• PROs 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

49
(No Transcript)
50
(No Transcript)
51
Lipid Catabolism

• 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)

52
Anaerobic Respiration No O2
53
Lactic Acid Fermentation

• Occurs during vigorous exercise when O2 is in
  short supply. Very inefficientbut quick!
• After glycolysis, the pyruvic acid is converted
  into lactic acid.
• L.A. is toxic and must be removed by delivering
  O2 to the cellsthis is why you suck wind after a
  sprint!!!

54
Lactic Acid Fermentation

• 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
  yogurtbacteria do the work!

55
Lactate Threshold

• Can be increased by training

56
VO2 Max Test

• 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!

57
VO2 Max

• Can be improved with training
• Genetics!
• Decreases with age
• http//www.youtube.com/watch?vFSL1jkwmWcs

58
Ethanol Fermentation

• 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.

59
Anaerobic Pathways

• Overheads

60
Complimentary Processes

• 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

61
Lab Page 131

• http//walking.about.com/library/cal/ucrockport.ht
  m