Download Notes for Ch 9 Respiration

3.7 Cell respiration ( Chapter 9 in Campbell's book)
3.7.1 Define cell respiration
[Cell respiration is the controlled
release of energy from organic
compounds in cells to form ATP]
Organic compounds store energy in covalent bonds…
mainly carbon-carbon and in electrons on the hydrogens
bonded to the carbons.
Glucose respiration yields 686kcals of energy per mole, it
is an exergonic reaction.
This means the products of respiration store less energy
than the reactants.
Adenosine Tri-Phosphate
ATP is the currency of energy
It is "spring-loaded" due to the negative charges of the
phosphate groups. ATP is regenerated by adding phosphate
to ADP … mainly done in mitochondria.
Phosphorylation
Phosphorylation includes any reaction that adds a
phosphate group to a molecule. Addition of the phosphate
group to the target molecule in a reaction gives energy to
the target molecule. ATP adds phosphate groups to
molecules.
NADH
(Nicotinamide Adenine Dinucleotide)
NADH is another energy carrier molecule like ATP. It is a
coenzyme used to generate ATP via the electron transport
chain. Electrons are first added to NAD+ . NAD+ receives
the electrons and a proton becoming a neutral NADH.
( a similar molecule is FADH2)
Option C
C 3.1
State that oxidation involves the loss of electrons from an
element, wheras reduction involves a gain of electrons; and
that oxidation frequently involves gaining oxygen or losing
hydrogen, wheras reduction frequently involves losing
oxygen or gaining hydrogen.
oxidation/reduction reactions…redox reactions
These are key to life's processes. Electrons are lost
from one molecule ( oxidation) and at the same time added
to another ( reduction). They are always coupled reactions.
It is the movement of electrons and protons ( H+) that
transfer energy. Oxygen is a strong oxidizer, it removes
electrons from other moleclules.
glucose is oxidized…it gives electrons to oxygen…which
is reduced.
Electrons move "downhill" towards the ultimate electron
acceptor…oxygen.
3.7.2 State that, in cell respiration, glucose in the
cytoplasm is broken down by glycolysis into pyruvate with
a small yield of ATP
Option C
3.2
Outline the process of glycolysis, including
phosphorylation, lysis, oxidation and ATP formation
Respiration occurs in 3 general phases: Glycolysis,
Kreb's cycle and the electron transport chain.
Glycolysis
means "splitting of sugar"
6-carbon glucose is split into two 3-carbon
pyruvate molecules
Initially, 2 ATP have to be added
The yield is 4 ATP and 2 NADH and 2 pyruvate
molecules and
Net gain is 2 ATP and 2 NADH + H+
substrate level phosphorylation
An enzyme adds the phosphate group to ADP
yielding the 2 ATP ( compare to oxidative phosphorylation
in the electron transport chain)
No oxygen is required at all, no CO2 is released
NADH can be converted to ATP via Electron
transport chain… if oxygen is available.
Pyruvate can enter the Kreb's cycle or undergo
fermentation
3.7.3 Explain that, during anaerobic cell respiration,
pyruvate can be converted in the cytoplasm into lactate, or
ethanol and carbon dioxide, with no further yield of ATP
[Mention that ethanol and carbon dioxide are
produced in yeast, whereas lactate is produced in
humans]
Fermentation
ATP can be produced at a lower rate without oxygen.
In order to keep generating ATP, the NAD+ has to be
regenerated… otherwise the reactions stop. Fermentation is
a means of regenerating this key oxidizing agent.
Alcohol fermentation transfers the H+ and electrons
from NADH to pyruvate in a couple of steps making
ethanol.
4
Lactic acid fermentation transfers the H+ and
electrons to lactic acid
Some yeasts, many bacteria and our muscle cells, can
alternate between aerobic and anaerobic respiration. If
oxygen is available, they use it because it can make as
much as 19 times more ATP
Option C
3.3
Draw and label a diagram showing the structure of a
mitochondrion as seen in electron micrographs.
Option C
3.6
Explain the relationship between the structure of the
mitochondrion and its function.
[ Limit this to cristae forming a large surface area for the
electron transport chain, the small space between inner
and outer membranes for accumulation of protons, and the
fluid matrix containing enzymes of the Kreb's cycle.]
3.7.4 Explain that, during aerobic cell respiration,
pyruvate can be broken down in the mitochondrion into
carbon dioxide and water with a large yield of ATP
Option C
3.4
Explain aerobic respiration, including the link reaction,
the Krebs cycle, the role of NADH +H+, the electron
transport chain and the role of oxygen.
Link reaction
Pyruvate is decarboxylated ( CO2 is removed) The
remaining two-carbon molecule (acetyl group) reacts with
reduced coenzyme A, and, at the same time, one NADH +
H+ is formed.
Krebs cycle…..in mitochondrial matrix, releases CO2
yields 6 NADH, 2 FADH2, 2 CO2, and 2ATP from
substrate level phosphorylation
Electron transport chain…on inner mitochondrial
membrane, uses oxygen, water is formed
yields 34 ATP This is oxidative phosphorylation
Kreb's Cycle… takes place in the mitochondrial matrix
3 carbon pyruvate is converted to 2 carbon Acetyl
CoA releasing CO2 The pyruvate is decarboxlylated… the
carboxyl group is removed from the pyruvate.
Each turn of the Kreb's cycle, 2 carbons enter as Acetyl
CoA, 2 carbons leave as CO2.
3 NADH, 1 FADH2 and 1 ATP are produced.
A glucose provides two turns of the cycle. ( 2 pyruvates
from glycolysis)
Note that most energy from the Kreb's cycle resides in the
NADH and FADH2
Electron transport chain
Electron transport chain is where the ATP is mostly
produced.
A series of enzymes are imbedded in the cristae, or inner
membrane of the mitochondria. Many of these enzymes,
cytochromes, incorporate iron, like hemoglobin does.
Option C
3.5
Explain oxidative phosphorylation in terms of
chemiosmosis
Chemiosmosis is how ATP is produced. The H+ proton is
the source of power to produce ATP
There is a concentration gradient across the inner
membrane. H+ is pumped into the mitochondria matrix by
the electron transport chain. When it diffuses back across
the membrane through special channels, the energy is used
to add P to ADP
Respiration is about 40% efficient. 60 % is lost as heat. By
comparison, automobiles extract 25% of energy in
gasoline.
In order to consume proteins, their amino groups must first
be removed… deamination. Then enzymes can break up
the carbon chains to enter the Kreb's cycle.
In order to consume fats, the fatty acids are broken up into
fragments that enter the Kreb's cycle as Acetyl CoA. Fatty
acids have lots of energy, and can produce twice as much
ATP as glucose per unit weight.
Intermediate molecules of the Kreb's cycle can be shunted
off to be used as precursors to other important molecules
needed in the cells. The 10 amino acids that we can make
are made from Kreb's cycle molecules.
Option C
3.7
Analyse data relating to respiration