Download Cellular Respiration II PPT

AP Biology
Cellular Respiration – Glycolysis,
Krebs Cycle, and ETC
Part 2
ATP Structure
Quick Review – How is ATP used as
an energy molecule in living
organisms? What is it about the
molecule that allows it to hold free
energy?
Phosphorylation using Free energy
Glycolysis Overview – Big Picture
• Glycolysis is a cytoplasmic process where one
molecule of Glucose (or another carbon-based
molecule) is ultimately broken down into two
pyruvates. This happens with or without
Oxygen.
• These pyruvates will then enter the
mitochondria and the Krebs Cycle.
• A net of 2 ATP are produced and 2 NADH are
also produced.
Energy Investment Phase &
Phosphofructokinase
We will follow the
carbons and pay
special attention to
the use of 2 ATP.
Why do this?
Energy Investment Phase
• This part of Glycolysis is called the Energy
Investment Phase, because it costs the cell 2
ATP to phosphorylate the glucose molecule.
• The end product of this part of glycolysis is
two molecules of G3P. See the connection to
photosynthesis?
Energy Payoff Phase
We will follow the
carbons again and pay
close attention to
production of 2 NADH
and 4 ATP.
Energy Payoff Phase
• In this part of glycolysis, the cell produces 4
ATP molecules by removing phosphates from
the carbon-based molecules already produced
in the process. It also creates 2 NADH. This
gives the whole process a net of 2 ATP made.
• The ultimate end product is 2 Pyruvates,
which will be slightly modified and added to
the Krebs Cycle
Is Oxygen present?
Cellular Respiration
Pyruvate Conversion and Krebs Cycle
Pyruvate Conversion
• The Krebs cycle is not perfect, so pyruvate
must be further converted before it can enter
the cycle.
• To do this, 1 carbon dioxide is removed from
pyruvate and a coenzyme (Coenzyme A) is
added to the remaining molecule. This
molecule, Acetyl Coenzyme A, can now enter
the Krebs cycle.
• Also, one NADH and one CO2 are produced.
Pyruvate
Conversion
MITOCHONDRION
CYTOSOL
NAD+
NADH
+ H+
Acetyl Co A
Pyruvate
Transport protein
CO2
Coenzyme A
Krebs Cycle – Big Picture
• The Krebs Cycle takes place in the
mitochondrial matrix, where there is plenty of
room for all of the intermediate molecules
and enzymes.
• The main goal is to produce as many NADH
and FADH2 as possible, from each Acetyl
Coenzyme A molecule that enters the cycle.
• 6 NADH total, 2 FADH2 total, 4 CO2, and 2 ATP
are produced.
Kreb’s Cycle Simplified
Actual Kreb’s Cycle
Cellular Respiration
Electron Transport Chain
Electron Transport Chain
BIG PICTURE
- The electron transport chain is made
up of a series of proteins that work
together to move electrons towards
Oxygen. Oxygen is the final electron
acceptor and is vital to cellular
respiration.
- Through several redox reactions, the
energy from these electrons is used
to pump hydrogens across the inner
mitochondrial membrane.
- By creating a concentration gradient
of hydrogens, ATP is made using ATP
Synthase.
Electron Transport Chain is
located on the inner FOLDED membrane
The electron transport
chain in cellular
respiration is located on
the inner mitochondrial
membrane. This
membrane is folded to
allow for a HUGE
amount of surface area
in each mitochondria
and many sets of
proteins that work as
electron transport
chains.
How does this compare
to photosynthesis?
Overview of Electron Transport Chain
Inner
mitochondrial
membrane
Glycolysis
Citric
acid
cycle
ATP
ATP
Oxidative
phosphorylation:
electron transport
and chemiosmosis
ATP
H+
H+
H+
H+
Intermembrane
space
Cyt c
Protein complex
of electron
carriers
Q
IV
III
I
ATP
synthase
II
Inner
mitochondrial
membrane
FADH2
NADH + H+
2H+ + 1/2 O2
H2O
FAD
NAD+
Mitochondrial
matrix
ATP
ADP + P i
(carrying electrons
from food)
H+
Electron transport chain
Electron transport and pumping of protons (H+),
Which create an H+ gradient across the membrane
Chemiosmosis
ATP synthesis powered by the flow
of H+ back across the membrane
Oxidative phosphorylation
NADH = 3 ATP
FADH2 = 2 ATP
*Look at where electrons are dropped off*
ATP Synthetase Complex using kinetic
movement of H+ (protons)
Cellular Respiration
Fermentation
Anaerobic Respiration
• Up to this point, we have been discussing aerobic
respiration (cellular respiration that occurs in the
presence of oxygen). However, organisms can also
produce small amounts of ATP through anaerobic
respiration as well.
• Fermentation is a process that is centered around
recycling electron carriers so that at least glycolysis
can continue. Glycolysis needs NAD+ to function, so
by doing this, the organism can produce enough
ATP to stay alive.
Alcohol Fermentation
Bacteria and Yeast
In alcohol fermentation, the
pyruvates are ultimately
converted into Ethanol, by
removing CO2 and bonding
Hydrogens in their place.
This helps to recycle
NADH/NAD+ so that
glycolysis can continue.
2 ATP are produced for each
glucose molecule and ethanol
is the end product.
Lactic Acid Fermentation
Animals such as yourself – Muscle Cramps!
In lactic acid fermentation,
the pyruvates are ultimately
converted into Lactate/Lactic
Acid, by removing one of the
Oxygen double bonds and
adding Hydrogens.
This helps to recycle
NADH/NAD+ so that
glycolysis can continue.
2 ATP are produced for each
glucose molecule and lactic
acid is the end product.