EXAM REVIEW
EXAM I CLASS AVERAGE = 59.1
EXAM II CLASS AVERAGE= 71.7
The class increased the average by 12.6 points!!
21/41 (51%) students received a C or better
31/41 (76%) students received a D or better
EXAM II Grade Distribution
NUMBER OF STUDENTS
12
10
8
6
4
2
0
A
B
C
GRADE
D
F
Trouble Spots
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Question 2
Question 5
Question 7
Questions 30-33
Question 35
Question 40
Question 44
Questions 46-49
NEXT EXAM
APRIL 12, 2011
COVERS WEEKS 7, 8, 9 and 10
WEEK 8
Glycolysis-Review (anaerobic)
Fermentation (anaerobic)
Cellular Respiration (aerobic)
The Metabolic Pool
Pages 134-147
Production of Energy from Food =
Cellular Respiration
I. Anaerobic (no oxygen used)
a. Glycolysis- Net gain of 2 ATP
b. Fermentation – No ATP gained
II. Aerobic (continuing from Glycolysis w/ Oxygen)
b. The preparatory reaction
c. Citric Acid Cycle
d. Electron Transport Chain and chemiosmosis
If OXYGEN is Present:
Pyruvate enters the mitochondria  Cell Respiration
If OXYGEN is not Present:
Pyruvate enters an anaerobic process called
fermentation
(yeast (fungi), some plants, some bacteria)
(bacteria, fungi (yeasts), animals)
Glycolysis Review
• Anaerobic Process
• No oxygen required
• Occurs outside the mitochondria
• Produces 2, 3-C Pyruvate molecules
OXIDATION
REDUCTION
LOSS OF ELECTRONS
GAIN OF ELECTRONS
RED-OX REACTION
Page 134
L E O the lion says GERRRR
OXIDATION
REDUCTION
LOSS OF ELECTRONS
GAIN OF ELECTRONS
H lost from glucose
H transferred to water
The 4 Steps of Cellular Respiration
GLUCOSE  2 pyruvate molecules
Oxidation  NADH
Net gain of 2 ATP
1.
GLYCOLYSIS-does not require O2
-Is therefore, anaerobic
-Occurs OUTSIDE of the mitochondria
2.
PREPARATORY REACTION
PYRUVATE  Two C Acetyl Group +CO2
This occurs 2X b/c 2 pyruvates are
-Requires O2
produced in glycolysis
-Is therefore, aerobic
-Takes place INSIDE of the mitochondria (matrix)
3.
CITRIC ACID CYCLE
-Requires O2
-Is therefore, aerobic
-Takes place INSIDE of the mitochondria (matrix)
4.
NADH +FADH2 give up e- to the “chain”
ELECTRON TRANSPORT CHAIN
(series of proteins in mito. cristae)
-Requires O2
e- are transported from high to low
-Is therefore, aerobic
-Takes place INSIDE of the mitochondria (cristae) energy states
More oxidation  NADH +FADH2
More CO2 is released
This cycle occurs 2X b/c 2 Acetyl groups
Were produced in the PREP Rxn.
2 ATP gained (1 per cycle)
32 ATP are produced via “chemiosmosis”
STEP/PHASE 1. Glycolysis
Occurs within the cytoplasm outside of the mitochondria
Is the breakdown of GLUCOSE into 2 pyruvate molecules
2-ATP molecules are used to “jump-start” the reactions in glycolysis
Page 138, section 8.2
Glycolysis
Begins as glucose diffuses into the cytoplasm of the cell from the blood stream
2 ATP are used to add 2 phosphate groups to the glucose, thereby energizing the
Glucose molecule
The energized glucose molecule splits apart and creates 2G3P, glyceraldehyde-3-phosphate,
(also known as PGAL) molecules
Glycolysis
ATP is used to add a phosphate group to the ends of the glucose molecule
This addition of phosphates energizes the glucose molecule
The energized glucose splits into 2 G3P molecules (3-carbon molecules)
Glycolysis
G3P gets oxidized as NAD+ gets reduced
2 BPG molecules are produced via the addition of phosphate
onto the ends of G3P
Glycolysis
phosphoenol pyruvate(PEP)
ATP is created as ADP is phosphorylated
Note the loss of the phosphate group from the 3-C molecules as ATP is created
Glycolysis
Metabolic Pathway
NET GAIN OF 2 ATP
Fermentation
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Break down of glucose in the absence of O2
Anaerobic
Occurs after glycolysis
Occurs if there is a continued absence of oxygen
Pyruvate is turned into “waste product”
– No more energy is produced
• What organisms do fermentation?
– Bacteria
– Yeast
– Animals
-Fungi
Two types of Fermentation
I.
Lactic Acid Fermentation (fungi-yeasts,
bacteria, Animals (muscles)
Pyruvate  Lactic Acid (C3H6O3) + NAD+
II.
Alcohol Fermentation (yeasts-fungi,
bacteria, some plants)
Pyruvate Ethanol (C2H5OH) + Carbon
Dioxide (CO2) + NAD+
Lactic Acid Fermentation
• Pyruvate is reduced by NADH to lactate
(pyruvate receives electrons from NADH
 NAD+)
• WHY do Fermentation?
– NAD+ is generated which can be “recycled”
for reuse in earlier reactions
– NAD+ can be reduced to NADH and then
NADH can reduce pyruvate once again
– ATP is continuously produced even w/o the
presence of oxygen, albeit very little ATP is
generated (only 2 ATP!)
Fig. 8.5 pg 138
Advantages/Disadvantages of
Fermentation
• Anaerobic bacteria and yeast can be used to
produce food products
– Ex. yeast fermentation yield CO2  bread rises
– Ex. yeast fermentation yields alcohol  produce wine
and beer (fermentation of fruit= wine, fermentation of
grain = beer)
– Ex. bacteria convert alcohol to acid (vinegar)
– Production of yogurt, cheese, sour cream via bacterial
fermentation
See page 139, Chapter 8
Advantages/Disadvantages of
Fermentation
• Lactic acid fermentation is critical for certain
animals and tissues
• Animals use lactic acid for rapid bursts of energy
• Lactic acid fermentation provides continued
production of ATP in absence of oxygen via
the cycling of NAD+
• Lactic acid and alcohol are toxic to cells,
bacteria and yeasts
• Lactic acid build up in humans causes change in
pH in blood
• Continued lack of O2 = oxygen debt (amount of
oxygen needed to rid body of lactic acid), heavy
breathing after exercise recovery
Glycolysis
2 ATP
2 NADH
With OXYGEN
2 Pyruvate
Without OXYGEN
a. The preparatory reaction
b. Citric Acid Cycle (2 ATP)
c. Electron Transport Chain and chemiosmosis
Lactic Acid Fermentation
OR
Alcohol Fermentation
TOTAL of 36-38 ATP produced
TOTAL of 2 ATP Produced
Cellular Respiration (Oxygen present)
After glycolysis occurs in the cytoplasm:
a. Prep Reaction (mitochondrial matrix)
b. Citric Acid Cycle/Krebs Cycle
(mitochondrial matrix)
c. Electron Transport Chain (cristae)
Cellular Respiration
C6H12O6 + 6O2  6CO2 + 6H2O + ENERGY
(Required!)
HIGH ENERGY
LOW ENERGY
LOW ENERGY
ENERGY RELEASED
Product of Glucose
Breakdown/ Bonds
Broken
Inside the Mitochondria
Majority of the ATP produced
from the breakdown of
Glucose occurs in the Mitochondria !
a. The Preparatory Reaction
• Occurs after glycolysis and before the
Citric Acid Cycle/Krebs Cycle
• The prep reaction converts the two 3-C
pyruvate to two 2-C acetyl group and
CO2 is released
• This is done with the help of Coenzyme A
THE PREP REACTION
Pg. 140 Chpt. 8
Glycolysis
Electrons are removed from PYRUVATE by NAD+ = Pyruvate is OXIDIZED
One prep reaction per pyruvate = 2 acetyl-CoA
Coenzyme A is a MOLECULE
A molecule of coenzyme A carrying an
acetyl group is referred to as acetyl-CoA
Coenzyme A oxidizes PYRUVATE
Prep Reaction
1. CO2 is released (to blood) as Pyruvate is carried into the
mitochondria
2. NAD+ oxidizes Pyruvate yielding NADH + H+
3. Coenzyme A oxidizes Pyruvate
FINAL PRODUCT is TWO Acetyl CoA molecules
b. The Citric Acid Cycle/Krebs
Cycle
Coenzyme A transfers the 2-C acetyl group in the
form of Acetyl CoA to the CAC/Krebs Cycle
Glycolysis
PREP rxn.
(from prep rxn)
Pg 141, Chpt. 8
CAC/ Krebs Cycle
NADH
1.
2.
3.
4.
Acetyl group joins with 4-C Oxaloacetate to form 6-C Citrate
Oxidation occurs when NAD+ accepts e- (3X) and FAD accepts e- (1X)
The acetyl group is oxidized to TWO CO2 molecules (4 total)
Substrate level ATP synthesis occurs (an enzyme passes a high energy
P to ADP to form ATP
5. A total of 6 CO2 molecules are produced, 2 from prep rxn, 4 from CAC
per glucose molecule
6. NADH and FADH2 are carrying high energy Phosphates!!
What happens to the high energy
NADH and FADH2 molecules?
• These molecules carry electrons to the
ELECTRON TRANSPORT CHAIN in the
CRISTAE of the mitochondria
STEP I.
NADH  NAD+ + 2 H+
FADH2 FAD + 2 H+
-NADH and FADH2 bring electrons to the ETC
-Both molecules are oxidized in order for ADP to
produce ATP
The ETC Players
COMPLEX I- NADH-Q reductase
(COMPLEX II- Succinate CoQ Reductase)
COMPLEX III- Cytochrome b-c reductase
COMPLEX IV- Cytochrome c Oxidase
ATP SYNTHASE COMPLEX
Cytochrome c
Coenzyme Q
NADH
Hydrogen Ions
ATP
FADH2
Electrons
ELECTRON TRANSPORT CHAIN pg 142
Electrons are passed from protein carrier
to carrier via a series of oxidationreduction reactions.
Protein Carriers:
COMPLEX I
NADH-Q reductase = An enzyme
that catalyzes the transfer of electrons from
NADH to Coenzyme Q
Coenzyme Q/Ubiquinone = An enzyme that
Transfers Electrons from Complex I and
Complex II to Complex III
Cytochrome b-c reductase/Complex III = helps
build proton gradient
Cytochrome c = electron carrier, transfers
Electrons from one protein to another
Complex II
Succinate CoQ Reductase= oxidizes FADH2
Cytochrome c Oxidase/Complex IV = Electrons
are transferred to oxygen to produce water
STEP I.
NADH  NAD+ + 2 H+
FADH2 FAD + 2 H+
STEP II.
NADH-Q reductase/Complex I gains electrons and is
reduced. HYDROGEN IONS are pumped into the
inner membrane space. Complex II oxidizes FADH2 to
FAD + 2H+
STEP III.
Electrons are lost to CoEnzymeQ which transfers the
electrons to Complex III (cytochrome reductase)
STEP IV.
Hydrogen from the reduction of FADH2 from complex
II are pumped to inner membrane space via
Cytochrome reductase/ Complex III
STEP V.
Cytochrome c and coenzyme Q continuously shuttle
electrons from complex to complex
Cyt c and Coenzyme Q only transport electrons
STEP VI.
Oxygen accepts electrons from complex IV,
cytochrome c oxidase, combines with hydrogen and
produces H2O
OXYGEN IS THE FINAL ACCEPTOR OF ELECTRONS IN THE ELECTRON
TRANSPORT CHAIN!!
Without oxygen, the electron transport chain would cease to function!!
Death results if oxygen is not present because the body would not be able to
produce/generate ATP
Mitochondrial
CRISTAE
Matrix
http://vcell.ndsu.edu/animations/atpgradient/first.htm
As HYDROGEN IONS are pumped
into the intermembrane space of
the mitochondria, an electrochemical
gradient develops.
Ten times as many H+ are in the
intermembrane space as there are
in the matrix.
This creates a strong [ ] gradient.
Hydrogen ions will want to enter the
mitochondrial matrix by flowing down
the concentration gradient
As hydrogen flows down the gradient
via the ATP synthase complex, the
enzyme ATP SYNTHASE synthesizes
ATP from ADP + P
ATP production depends on the
H+ gradient!!
ATP produced in the matrix is
quickly shuttled out for use in body
CHEMIOSMOSIS
• Movement of Hydrogen Ions from
innermembrane to the mitochondrial matrix
MATRIX
INNERMEMBRANE
ATP SYNTHASE
ATP Synthase
• Is an enzyme
• Produces ATP from hydrogen ions flowing
down their concentration gradient FROM the
inner mitochondrial membrane to the matrix
• ATP is transported out of the matrix via an
ATP channel protein
• At any time, the amount of ATP in human
body is only enough to sustain 1 minute of
life. ATP synthase must work CONSTANTLY
ENERGY YIELD from
GLUCOSE METABOLISM
2 ATP from glycolysis
2 ATP from Krebs/ CAC cycle
32 or 34 ATP from Electron Transport Chain
TOTAL = 36 or 38 ATP produced per 1
glucose molecule
WHY???
36 or 38 ATP
In some cases:
-2 NADH are produced during glycolysis
-Sometimes NADH cannot cross
mitochondrial membranes to go to ETC,
but the e- from NADH can be shuttled
-This shuttling costs the cell 1 ATP for each
NADH that is shuttled which reduces the
count of ATP from 38 to 36
-36 is the usual number of ATP produced
How much energy is available
to the cell per glucose?
The difference in energy content between the
reactants (C6H12O6 and O2) and products (CO2
and H2O) is 686 kcal
ATP phosphate bond has 7.3 kcal
36 ATP are produced  7.3*36= 263 kcal
Of the 686 kcal energy difference, 263/686 kcal of
energy is transferred from glucose to ATP =
39%, the rest of the energy is lost as heat
Metabolic Pool
• Metabolic substrates are used over and over
again
• There is a “pool” or “holding area” of these
substrates = Metabolic Pool
• Metabolic pool substrates serve as entry points
for the degradation or synthesis of larger
molecules
• Ex. Carbs, Fats and proteins
Metabolic Pathways- 2 types
1- Catabolic (Catabolism)- break down
Food molecules are the source of substrates
(“pool”)- Fats, Carbs, Proteins
Food molecules contain large amounts of stored
energy in their chemical bonds
Bonds are broken and food is broken down to
basic subunits
2- Anabolic (Anabolism)- build up
Molecules are formed from subunits in “pool”.
Molecules are “re-formed” from the basic
subunits.
Fig. 8.11 pg 145
Metabolic Pool
Concept
Proteins, Carbs
Fats are broken
Down into their
Basic subunits which
Are ‘catabolized’ to
Produce ATP
Fatty acids can be used to
Produce up to 108 ATP
molecules!
Fats are an efficient form
of stored energy
Why learn or know any of
this?
There are many different types of
mitochondrial diseases
These diseases result from improper protein
function
Diseases cause the most damage to cells of
the brain, heart, liver, skeletal muscles,
kidney and the endocrine and respiratory
systems.
Types of mitochondrial
diseases
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Alpers Disease
Barth syndrome
Beta-oxidation Defects
Carnitine-Acyl-Carnitine Deficiency
Carnitine Deficiency
Creatine Deficiency Syndromes
Co-Enzyme Q10 Deficiency
Complex I Deficiency
Complex II Deficiency
Complex III Deficiency
Complex IV Deficiency
Complex V Deficiency
COX Deficiency
CPEO
CPT I Deficiency
CPT II Deficiency
Glutaric Aciduria Type II
KSS
Lactic Acidosis
LCAD
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LCHAD
Leigh Disease or Syndrome
LHON
LIC (Lethal Infantile
Cardiomyopathy)
Luft Disease
MAD
MCAD
MELAS
MERRF
MIRAS
Mitochondrial Cytopathy
Mitochondrial DNA Depletion
Mitochondrial Encephalopathy
Mitochondrial Myopathy
MNGIE
NARP
Pearson Syndrome
Pyruvate Carboxylase Deficiency
Pyruvate Dehydrogenase
Deficiency
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POLG Mutations
Respiratory Chain
SCAD
SCHAD
VLCAD
Plant and Tree Respiration
How do plants respire?
PHOTOSYNTHESIS!!
The sun is the source of energy for producing carbohydrates in plants
Energy flow occurs through a similar ETC in the chloroplasts in plant cells
Photosynthesis v Cell Resp.
Photosynthesis
Cell Respiration
-Thylakoid discs
-ETC in thylakoid
energized by sun
-H+ electrochemical
gradient
-Calvin Cycle
-NADPH
-Cristae
-ETC in cristae energized
by glucose e-H+ electrochemical
gradient
-Citric Acid Cycle
-NADH
THIS WEEK IN LAB
Membranes and Biological Transport
You should all be experts on this!!
QUESTIONS??
HOMEWORK
Read all of Chapter 7- PHOTOSYNTHESIS
Do all of the self test questions