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HONORS BIOLOGY CHAPTER 6
Breaking Down Glucose
6.1
• Ultimate source of
energy
• Photosynthesis
and Cellular
Respiration-how
related?
Breathing and Cellular Respiration
• Breathing: how our body
inhales and exhales to take in
oxygen and release carbon
dioxide
• Cellular Respiration: how our
cells break down food sources
(ie., glucose) to produce energy
(ATP).
Respiration Really is...
• Cellular respiration = breakdown
of organic molecules (for energy)
in the presence of oxygen (in
mitochondrion)
6.3 Cellular Respiration Equation
Is this endergonic or exergonic?
Cellular Respiration Equation
ATP
Is this endergonic or exergonic?
Glucose breaks bonds and gives off energy (as
seen on right side of the equation).
Fill in the Blanks
6.4 Energy Units
• Kilocalories (kcal)
• = Calories
• = 1000 calories
• = quantity of heat needed to
raise 1 kg of water by 1oC
Daily Human Needs
• 2,200 kcal of energy per day
• Walking at 3 mph (burn 245 kcal/hour), how
far would you have to travel to “burn off” the
equivalent of a slice of pizza of about 475
kcal?
Daily Human Needs
• 2,200 kcal of energy per day
• Walking at 3 mph (burn 245 kcal/hour), how
far would you have to travel to “burn off” the
equivalent of a slice of pizza of about 475
kcal?
• ~2 hours
6.5 Where does the energy come from?
• The bonds (electrons) with more
energy (C6H12O6)and forming
bonds with less energy (CO2 and
H2O).
6.3 Burn 1 glucose molecule with fire
• ~ 100 ATP molecules
• 100% energy released
• BUT, in cells only about 34% goes
to use in ATP molecules
• The rest is lost as heat
6.5 Cell’s Slow
Burn
• Cells tap energy
from electrons
“falling” gradually
from organic fuels
to oxygen.
• This is slower and
more controlled
than just burning it
with fire.
What drives this to happen?
• OXYGEN
• A strong tendency to pull
electrons from other atoms
• Oxygen is the “ultimate electron
acceptor”
REVIEW: Catabolic Pathways
• Metabolic
pathways that
release stored
energy by
breaking
down complex
molecules
To what molecule is the energy
shuttled?
•ATP
• ADP to ATP
animanim
ation
•
•
•
•
“Redox reaction”
Oxidation – Reduction Reaction
• Reduction
Oxidation
loss of electrons • addition of
electrons
to
from one
another
substance
substance
Loss of H
• Gain of H
NADH NAD+
• NAD+ NADH
We don’t see e-, but we see H atoms.
C6H12O6+ 6O2
6CO2+6H2O+ATP
• (hydrogen atom =
one proton and one electron)
We don’t see e-, but we see H atoms.
C6H12O6+ 6O2
6CO2+6H2O+ATP
• (hydrogen atom =
one proton and one electron)
LEO = loss of electrons = reduction
How to remember…
• "Leo goes Ger”
• Loss of electrons = oxidation
• Gain of electrons = reduction
Fill in the Blanks: H+ 2H
reduction NAD+ NADH oxidation
becomes oxidized becomes reduced
carries 2 eb
What is NAD+?
• nicotinamide adenine
dinucleotide
• Coenzyme from vitamin niacin
• used to shuttle electrons in redox
reactions
• Turns NAD+ into NADH
NAD+ to NADH
Electron Carrier
(empty)
• A.k.a.
NAD+
“hydrogen
carrier”
• Electron taxi
NADH
ecab
(full with e-)
Lose electrons
• C4H6O5
• Oxidized
• NAD+
• Reduced
C4H2O5
Lose e- (H)
NADH
Gain e- (H)
Which has more energy?
• NAD+ or NADH?
• Answer: NADH
• What would the enzyme
dehydrogenase do?
• Strips two H from NADH
+
NAD
• Can NAD+ be
recycled?
• Yes
• McGraw-Hill
NAD+
Animation
 NADH
Electron Transport Chain
• Organic molecules with an abundance of C-H
bonds are a source of e- with a potential to fall
closer and closer to oxygen.
• An e- loses its potential when it shifts from a
less electronegative atom (doesn’t attract eas much) to a more electronegative atom
(attracts e- more).
ETC
Animation of Energy Release from an Electron
Transport System
• Electron
Transport
Chain
• Electrons are
passed from
the hydrogen
carrier NADH
to oxygen from
one molecule
to another
What keeps…
• The electrons moving down the chain?
• Each e- carrier molecule has
greater affinity for e- than its
uphill neighbor
• Electron Transport System and ATP Synthesis
(little movie)
• Krebstca (animation)
Where are ETC’s found?
• In membranes of:
–Mitochondria
–Chloroplasts
Everything you wanted to know about
the Mitochondrion
• Mitochondrion
Animation
• Note many folds
(cristae) of inner
membrane
• This increases
surface area
Mitochondrion
Matrix contains mDNA
(mitochondrial), enzymes, and
ribosomes-site of Krebs cycle
6.6
3 Stages of Cellular Respiration:
• 1. Glycolysis- occurs in cytoplasm
• Glucose
2 mols. of pyruvate
• 2. Pyruvate oxidation and citric acid cycle occurs in mitochondrion
• Pyruvate
Acetyl CoA
CO2 + NADH
• 3. Oxidative phosphorylation-in
mitochondrion uses ETC and chemiosmosis
in mitochondrion to make lots of ATP
Cellular Respiration
• Cellular respiration converts the potential
energy of glucose into usable energy of
ATP.
• THERE ARE 2 WAYS THE ATP IS
GENERATED.
•

2 Ways to Make ATP
• Substrate-Level
• Oxidative
Phosphorylation
Phosphorylation
• (without a
• diffusion of
membrane; it
particles
occurs in the
cytoplasm or matrix
through a
of mitochondrion
membrane
with help of an
produces
ATP
enzyme)
Substrate-Level Phosphorylation
• Use of enzymes
(not membranes)
to join P to ADP
to make ATP
Oxidative Phosphorylation
• Uses a membrane (of mitochondrion or
chloroplast) to pass electrons down the
electron transport train to a final electron
acceptor.
6.7 GLYCOLYSIS
• A. Energy Investment Phase
–Glucose is phosphorylated into
2 molecules of G3P
–Uses 2 ATP
GLYCOLYSIS
• B. Energy Payoff Phase
–2 G3P break down to 2 pyruvates
–Two NAD+ add 2 electrons
2
NADH + 2H+
-4 ATP form, net gain of 2 ATP
Glycolysis
• Start with 6-carbon glucose and
breaks into two 3-carbon pyruvic
acid molecules (or pyruvate)
• glucose + 2 NAD+ + 2 ADP + 2 Pi
2 pyruvate + 2 NADH + 2 ATP
• Glycolysis actually has 9
steps…but you only
need to learn that
these molecules
formed between
glucose and pyruvic
acid are called
• intermediates
One
Intermediate
•G3P
• = PGAL
• = Glyceraldehyde 3-phosphate
• =Phosphoglyceraldehyde
Glycolysis: What do I need to know?
• Needs 2 ATP to get • NET GAIN
started
2 ATP’s
• Makes 4 ATP
• Net Gain of 2 ATP
• Glycolysis
• Splits glucose into
Animation
2 pyruvates
(nice
big
carbons)
• Makes NADH
But...
• Pyruvic acid itself does not enter
the Krebs cycle
• Say What?
Pyruvate Oxidation or “Cut and Groom”
“Grooming” Pyruvic Acid Haircut
and Conditioning
“HAIRCUT”
“CONDITIONING”
As NADH is
reduced to
NAD+…pyruvic
acid is oxidized
(carbon atom
removed as CO2)
Coenzyme A (from B
vitamin) joins the 2-c
fragment
MAKES-Acetyl
Coenzyme A or CoA
Ready to GO
• The Acetyl-CoA is now ready to enter
the Krebs cycle
Hans Krebs
(1900-1981)
Yeah, he got a
Nobel Prize, too
Pyruvate Oxidation:
“Cut and Groom”
Krebs Cycle
• Only 2-C of acetyl
enters
• (Coenzyme A
is recycled)
• Occurs in
mitochondrial matrix
Krebs Cycle Occurs in the Matrix
• This one
OAA = 4-C
(recycled)
+ 2-c acetyl
6-C citric acid
(temporary)
Krebs Cycle
McGraw-Hill ATP synthesis and ETC animation
1 ATP
3 NADH2
1 FADH2
2 pyruvates
=2
=6
=2
McGraw-Hill How the Krebs Cycle Works Animation
Chemiosmosis and ETC
• Flow of e- from NADH + FADH2 shuttle
down the ETC to a final electron
acceptor (oxygen)
• Each of the O2 combines with 2 e- and 2
H+ to form H2O
• Energy from e- transports H+ ions
across the inner membrane so ADP + P
forms ATP
ETC and CHEMIOSMOSIS
Most ATP production occurs by oxidative
phosphorylation
Occurs along the inner membrane of the
mitochondrion
The electron carriers bring e- and H+
• FORMED IN THE KREBS CYCLE
• NADH brings 2 e- and H+
• FADH2 brings 2 e- and 2H+
Why do the electron carriers unload
their electrons?
• Oxygen is the final electron acceptor because
it has a high electronegativity (attractions to
electrons).
• Electron Transport -Electron Carriers – Animation (3:33) –nice
explanation of all parts of ETC
• Another ETC Chemiosmosis Animation
`
Electron Carriers
What are the two
electron carriers?
What do they drop off
in the inner
membrane?
What do they drop off
that diffuses through
the inner membrane?
• Transfer of Energy of Electron Carriers Animation
Where do all the H+ ions that collected in the
intermembrane space move through, down the gradient?
ETC
• Electron transfers (redox) between an electron
donor (such as NADH) and an electron
acceptor (such as O2) with the transfer of H+
ions (protons) across a membrane.
• ETC animation (Zoom in on nice animation as the electron
carriers drop off their e- and H+)
• Student Recommended Cell Resp Animation
• ETC (VCAC) NDSU Virtual Cell Animations ATP Synthase (VCAC)
COUNT THE TOTAL ATP’s
“Down the Gradient”
Note more H+
ions on
intermembrane
side of the
membrane INNER
MEMBRANE
The movement
“down the
gradient”
produces energy
MATRIX
Chemiosmosis and ETC
• H+ ions can only pass through a
special port ATP synthase (see
knobs on cristae)
Chemiosmosis
• Diffusion of
excess H+ ions
across a
membrane from
high to low
concentration
• Generates energy
to cause
ADP + Pi = ATP
Where does chemiosmosis occur?
• In Protein
Complexes called
ATP Synthase
in inner membrane
World’s smallest
rotary motor 
Chemiosmosis
Powers Most of ATP Produced in the
breakdown of glucose
• Glycolysis -2 ATP
• Krebs Cycle - 2 ATP
• Chemiosmosis/ ETC - 34 ATP
Cellular Respiration Equation
C6H12O6 + 6O2 > 6CO2 + 6H2O + ATP
Where does all the ATP come from?
•1 NADH = 3 ATP
•1 FADH2 = 2 ATP
Review of ATP YIELD
(Ideally)
•
•
•
•
Need 4 ATP to start glycolysis
Glycolysis makes 2 ATP
Krebs Cycle makes 2 ATP
ETC/Chemiosmosis makes 34 ATP
• TOTAL about 38/molecule
of glucose
TOTAL ATP’s
Glycolysis
2 ATP (borrowed 2 to start, made 4 ATP, net of 2 ATP)
*2 NADH (= 4 ATP; 6 ATP made but 2 ATP used to move
across the membrane)
Formation of Acetyl CoA
*2 NADH (= 6 ATP)
*sent to ETC
Krebs Cycle
*6 NADH (= 18 ATP)
*2 FADH2 (= 4 ATP)
2 ATP
Total Yield
Glycolysis produces 2 ATP
aerobic respiration produces 34 more ATP
NOT JUST
FOR
GLUCOSE
POISONS
• Rotenone-binds to first
ETC protein to prevent epassing on
• Cyanide-bind to fourth
protein in ETC
(was in famous Tylenol
tampering in 1982)
POISONS
• Oligomycin -blocks H+
through ATP synthase
• DNP- enormous increase in
metabolic rate – all energy
lost as heat (once given as a
weight loss pill)
Lactic Acid
Fermentation
In animals
(muscles) if
lack of oxygen
Note: no CO2
formed
The lactic acid causes stiffness that
goes away after a few days.
This is due to the stopping of strenuous
activity to allow aerobic conditions to
return to the muscle.
The lactic acid can be converted into
ATP via the normal aerobic respiration
pathways.
Fermentation regenerates NAD+
(so it can be used to pick up H+ and e- again)
Lactic Acid Foods
•
•
•
•
Yogurt
sauerkraut
soy sauce
sourdough bread
kimchee
Alcoholic Fermentation:
In yeast, bacteria
• Forms ethanol and CO2
• Also, NADH regenerated back to NAD+
Grapes
fermenting
TYPES OF ANAEROBES
• OBLIGATE ANAEROBES –require anaerobic
conditions
Clostridium
difficile
• FACULTATIVE ANAEROBES – can use either
oxygen or not, but will use aerobic conditions
if O2 first is present
Bacillis anthracis
• Tube 1: Obligate Anaerobe -- note the absence of
growth in the top portion of the broth where oxygen is
present.
• Tube 2: Obligate Aerobe -- note the growth is only in
the top portion of the tube where oxygen is present.
• Tube 3: Aerotolerant -- note the uniform growth from
top to bottom.
• Tube 4: Facultative -- note the uneven distribution of
growth from top to bottom (more growth at the top).
• Tube 5: Obligate Aerobe -- note the growth is only in
the top portion of the tube where oxygen is present.