Download 8.1 Cell Respiration (AHL) day 2

Left-over outcomes from
yesterday…
Cell Respiration AHL
8.1 – Day 2
A closer look at Krebs Cycle and the ETC
8.1.4Explain aerobic respiration, including the link
reaction, the Krebs cycle, the role of NADH + H+, the
electron transport chain and the role of oxygen.
8.1.5Explain oxidative phosphorylation in terms of
chemiosmosis.
8.1.6Explain the relationship between the structure of
the mitochondrion and its function.
So what do we remember
from last class?
Glycolysis
Glycolysis
ANIMATION! ☺
OIL RIG!
Onto today’s show!
8.1.4 Explain aerobic respiration, including the link reactions, the Krebs
cycle, the role of NADH+ H+, the Electron Transport Chain and the role
of Oxygen.
The link reaction
Link Reaction: oxidative decarboxylation of pyruvate
Each 3-carbon pyruvate loses 1 CO2 forming a 2-carbon
acetyl fragment, carried by CoA as acetyl-coenzyme A
and NADH+ H2
http://images.slidesharecdn.com/8-1c3respiration100707014003-phpapp02-slide-52.jpg?1278484869
Link reactions - summarized
Now that glycolysis is done, we can enter into the
mitochondria and really have some fun!
8.1.4 Explain aerobic respiration, including the link reactions, the Krebs
cycle, the role of NADH+ H+, the Electron Transport Chain and the role
of Oxygen.
Kreb Cycle:
2-carbon acetyl joins with 4-carbon molecule, forming a 6carbon molecule which is oxidized, releasing 2 CO2
This allows reduction of ADP to ATP, FAD to FADH2, 3
NAD to 3 NADH+ H+
http://images.slidesharecdn.com/8-1c3respiration100707014003-phpapp02-slide-64.jpg?1278484869
8.1.4 Explain aerobic respiration, including the link reactions, the Krebs
cycle, the role of NADH+ H+, the Electron Transport Chain and the role
of Oxygen.
Animation!
Electron Transport Chain (ETC or ETS)
Mitochondrial inner membrane proteins form a transport chain for
electrons and protons.
NADH+ H+ arrive at the first carrier and transfers 2 electrons (e’s)
and 1 hydrogen (H +)
Another H + is picked up from the matrix solution
The 2 e’s and the 2H + s are carried from the inner to outer face,
where the two e’s return, pick up another pair of H + s and repeat
the trip two more times for a total of 3 round trips.
FADH2 enters into the ETC further along and thus pumps only two
pairs of H + s into the inter-membrane space.
8.1.4 Explain aerobic respiration, including the link reactions, the Krebs
cycle, the role of NADH+ H+, the Electron Transport Chain and the role
of Oxygen.
Oxygen
Oxygen is the final electron acceptor at the end of the
ETC
As oxygen accepts a pair of electrons, it also accepts
two protons which join with the electrons to produce the
two hydrogen atoms thus forming water.
ATP Synthase Pump (simple)
Oxidative phosphorylation
8.1.5 Explain oxidative phosphorylation in terms of
chemiosmosis
Final stage of aerobic respiration
Involves the electron transport chain
Takes place on the cristae
Series of protein complexes (electron carriers) are arranged
in the phospholipid bilayer of the inner mitochondrial
membrane (**see photo that Mrs. LeBlanc annotated).
Electrons pass from one complex to the next.
Hydrogen ions are pumped from the matrix to
intermembrane space (changes pH in intermembrane space
– making it more acidic)
8.1.6 Explain the relationship between the structure of the
mitochondrion and its function.
Proton gradient drives production of ATP by enzyme ATP
synthetase (chemiosmotic theory- synthesis of ATP is coupled to
electron transport and via a concentration gradient of protons).
Outer Membrane: separates mitochondria from
cytoplasm based on fluid mosaic model.
Net Result: 1 NADH + H supplies enough energy to produce 3
Intermembrane space: low pH = high concentration of
NADH + H and FADH2 are returned to oxidized forms NAD and
Inner membrane: folded into cristae, increasing SA for
+
ATP from 3 ADP + 3 Pi and 1 FADH2 supplies enough energy to
produce 2 ATP from 2 ADP + 2 Pi.
+
+
FAD. Essentially, NADH + H + and FADH2 transfer their energy to
ATP via electron carriers.
Last protein complex H + and electrons reduce oxygen to form
water.
H+s from ETC/proton pump
ETS and ATP synthetase; impermeable to H+s,
electron carriers and ATP synthetase embedded
among phospholipid molecules.
Matrix: contains enzymes for oxidative decarboxylation
and Krebs cycle.
Where does it all take place?
Glycolysis produces pyruvate in the cytoplasm.
Pyruvate is transported to the matrix where it is decarboxylated to
acetyl CoA.
Acetyl CoA enters into the Krebs cycle
NADH and H+ and FADH2 from Krebs cycle give electrons to the
electron carriers in the inner membrane.
Electrons move through the membrane as they are passed
between electron carriers in a series of REDOX reactions. H+ are
pumped from the matrix into the intermembrane space, creating a
potential difference. A concentration gradient drives the H+ back to
the matrix through ATP synthase which uses energy release to
combine ADP and Pi into ATP which is released into the matrix.
Time to rock out!
http://www.youtube.com/watch?v=VCpNk92uswY&feat
ure=player_embedded