Download Cell Respiration

Date _________
• Chapter 7~Cellular
Respiration: Harvesting
Chemical Energy or The
Biochemistry of
heterotrophs
Principles of Energy Harvest
Organisms who can’t make their own
food are called heterotrophs.
This means they must convert the
the energy found in the
organic compounds they eat.
They do this thru a series of
catabolic and anabolic redox
pathways. Overall:
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + E
(ATP + heat)
Redox reactions
•
•
More Oxidation-reduction
Reducing agent:
•
Oxidizing agent:
•
So, in cell respiration:
Glucose is oxidized (reducing agent)
and oxygen is reduced. (oxidizing
agent)
• (The main Redox reactions)
So make connections!
So let’s brainstorm what
heterotrophs are going to do in
their biochemical pathways…..
Compared to plants
• Similarities
• Differences
Now we have to really be
careful!
C6H12O6
Why ATP?
•
•
•
•
Less stable=higher NRG potential
Recyclable (rechargeable) (ADP, AMP)
36 ATP for every 1 glucose
More easily stored and retrieved
Double H baby sitters required!!!
Now we are really “playing with
fire”!!!
• NAD+ (nicotinamide
adenine dinucleotide) And
FAD+ (flavin adenine
dinucleotide)
• Both collect electrons
from the intermediate
reactions and shuttle
electron (-) and proton (+)
ions across membranes.
• Oxygen eventually
collects all the hydrogen
atoms.
• FAD is a better carrier,
but more energy
expensive to make
Cellular respiration Overview
• Glycolysis: cytosol; degrades glucose
into PGAL which becomes pyruvate after
each PGAL loses an H (collected)
• Kreb’s (Citric) Cycle: mitochondrial
matrix (just inside the mito); pyruvate
into carbon dioxide, more H’s lost and
collected
• Electron Transport Chain: inner
membrane of mitochondrion; H electrons
passed to oxygen
Glycolysis (what you need to know)
• 1 Glucose +2 ATP +4 NAD+ 4 ADP + 4 P  2 PGAL + 2
NADH 2 pyruvate + 4 ATP + 4 NADH + 2 ADP+ 2 P
• So, 1 glucose = 2 pyruvate, 2 ATP (net) and 4 NADH
• Energy investment: Cell “burns” 2 ATP (ATPADP) to
initiate process, as glucose is stable and won’t catabolize on
its own.
• Energy payoff : 1) 4 ATP are produced by substrate-level
phosphorylation (NET gain of 2 ATP) 2) 4 NAD+ are
reduced to NADH, 3) 2 pyruvates (C3H4O3) that can still
be used.
• Anaerobic and it Occurs in the cytosol (Pyruvate and
pyruvic acid are the same thing)
• Random pic alert!
Glycolysis
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Stage or phase 2: Citric Acid Cycle (Kreb’s Cycle)
• First, unstable pyruvate must be temporarily stabilized. To
do this, pyruvate is combined a helper called “co-enzyme
A” (CoA) to form a compound called Acetyl-CoA. We
must release CO2 to do this and release some hydrogen so
allow different NAD+ to pick them up as NADH.
• This binding to co-enzyme A (CoA) accomplishes 2
important things, 1-it increases the permeability into the
mitochondrion and 2- slows degradation of the pyruvate *
• * 2 Carbon acetyl CoA binds to 4 Carbon oxaloacetate to
form a 6 Carbon Citric Acid (citrate)…COOL!
CAC continued
• 2 carbon Acetyl CoA + O2 + NAD + FAD + ADP + P +
oxaloacetate Citrate + 4NADH + 1ATP +1 FADH2 + 4
CO2 + CoA
• Multiple the numbers by 2 as 1 glucose = 2 pyruvates
• Again (like Glycolysis, only using substrate level
phosphorylation)
• Aerobic as oxygen required to remove carbon in the form
of CO2 (Bohr’s Shift) Cyclic as we regenerate CoA each
round
• Occurs in the inner space of the mitochondrion called the
matrix (See next diagram)
The mito!
CO2 and O2-Bohr’s Shift
pH, temp, blood pressure
HOMEOSTASIS
• Man that’s a big
head…..JK
Now...why did we collect all
those H’s???
To harness their power!!!
Third phase or stage: Electron transport chains
• Uses electron carrier molecules (NAD and FAD) along
with special membrane proteins embedded in the cristae
to safely move Hydrogen’s electron and proton power
(proton motive force) ultimately to ATP Synthase.
• Ubiquinone, Cytochrome C, NADH reductase
• Use the proton motive force to make even more ATP .
Many shuttle stations due to the folding of the cristae
• Will use oxygen to drive the movement of hydrogen ions
from carriers so we call this oxidative phosphorylation.
• Hydrogen’s proton is moved through the cristae’s
proteins and to waiting oxygen, while the resulting
electrons follow but are shuttled through specific places
in the cristae first. They too eventually find the water!
•
http://video.search.yahoo.com/yhs/search;_ylt=AwrTcdWlL7dYaiEAqVgPxQt.?p=electron+transport+chain&fr=yhs-iryfullyhosted_003&fr2=piv-web&hspart=iry&hsimp=yhsfullyhosted_003&type=wncy_popjar_15_34&vm=r#id=40&vid=86c40148754ea83030746b806a4a37d7&action=view
ETC=Chemiosmosis
• When we are done,
we will make about
34 ATP and water
for the energy
investment of
ZERO!
Remember, this ability to use
ions is brought to you by the
cristae!!
• Semipermeable
membrane….
• Allows what to
cross?
• Why important
here??
Electron transport chain
Review/ATP made during Cellular
Respiration
• Glycolysis:
2 ATP (substrate-level
phosphorylation)
• Citric (Kreb’s) Cycle:
2 ATP (substrate-level
phosphorylation)
• Electron transport: (oxidative
phosphorylation)
2 NADH (glycolysis) = 6ATP
2 NADH (acetyl CoA) = 6ATP
6 NADH (Citric) = 18 ATP
• 2 FADH2 (Citric) = 4 ATP
• 38 TOTAL ATP/glucose
Whew!!!!
Related metabolic processes
• Fermentation: No O end
products are ethanol, CO2
OR lactic acid and CO2
Glucose pyruvate to
ethanol OR lactic acid~
and CO2 (anaerobic)
• Facultative anaerobes
(yeast/bacteria)
2
All roads…..