Selaginella: features, morphology ,anatomy and reproduction.
9 cellular respiration
1.
2. Organisms must take in
energy from outside
sources.
Energy is incorporated
into organic molecules
such as glucose in the
process of
photosynthesis.
Glucose is then broken
down in cellular
respiration. The energy
is stored in ATP.
4. Energy in food is stored as carbohydrates
(such as glucose), proteins & fats. Before
that energy can be used by cells, it must be
released and transferred to ATP.
5. Aerobic Cellular Respiration: the process that
releases energy by breaking down food
(glucose) molecules in the presence of oxygen.
Formula: C6H12O6 + 6O2 → 6CO2 + 6H2O +~ 36 ATP
Fermentation: the partial breakdown of glucose
without oxygen. It only releases a small amount
of ATP.
Glycolysis: the first step of breaking down
glucose—it splits glucose (6C) into 2 pyruvic
acid molecules (3C each)
6. The transfer of electrons during chemical
reactions releases energy stored in organic
compounds such as glucose.
Oxidation-reduction reactions are those that
involve the transfer of an electron from one
substance to another.
8. becomes oxidized
becomes reduced
In cellular respiration, glucose is broken down and
loses its electrons in the process.
The glucose becomes oxidized and the Oxygen is
reduced.
Redox Reactions of Cellular Respiration
9. In cellular respiration, glucose is broken down
in a series of steps.
As it is broken down, electrons from glucose
are transferred to NAD+, a coenzyme
When it receives the electrons, it is converted to
NADH.
NADH
represents
stored energy
that can be
used to make
ATP
10. NADH passes the electrons to the electron
transport chain, a series of proteins embedded
in the inner membrane of the mitochondria.
The electrons (and the energy they carry) are
transferred from one protein to the next in a
series of steps.
11. Freeenergy,G
Freeenergy,G
(a) Uncontrolled reaction
H2O
H2 + 1
/2 O2
Explosive
release of
heat and light
energy
(b) Cellular respiration
Controlled
release of
energy for
synthesis of
ATP
2 H+
+ 2 e–
2 H + 1
/2 O2
(from food via NADH)
ATP
ATP
ATP
1
/2 O2
2 H+
2 e–
Electrontransport
chain
H2O
Energy is released a little at a time, rather than one big explosive reaction:
20. Substrate-level
phosphorylation:
Phosphate is added to
ADP to make ATP by
using an enzyme:
Oxidative
phosphorylation:
Phosphate is added to
ADP to make ATP by
ATP Synthase—a
protein embedded in
the mitochondria
membrane (requires
O2)
WAY MORE
EFFICIENT!!
PRODUCES LOTS
MORE ATP!
21. “Glyco”=sugar; “lysis”=to split
In this first series of reactions, glucose (C6) is
split into two molecules of pyruvic acid (C3).
This occurs in the cytoplasm of cells and does
not require oxygen.
This releases only 2 ATP molecules, not
enough for most living organisms.
22. Energy investment phase
Glucose
2 ADP + 2 P 2 ATP used
formed4 ATP
Energy payoff phase
4 ADP + 4 P
2 NAD+
+ 4 e–
+ 4 H+
2 NADH + 2 H+
2 Pyruvate + 2 H2O
2 Pyruvate + 2 H2OGlucose
Net
4 ATP formed – 2 ATP used 2 ATP
2 NAD+
+ 4 e–
+ 4 H+
2 NADH + 2 H+
Glycolysis
23. The Citric Acid Cycle (also called the Kreb’s
Cycle) completes the breakdown of pyruvate
and the release of energy from glucose.
It occurs in the matrix of the mitochondria.
24. In the presence of oxygen, pyruvate enters the
mitochondria.
Before the pyruvate can enter the Citric Acid
Cycle, however, it must be converted to Acetyl
Co-A.
Some energy is released and NADH is formed.
26. The Acetyl Co-A enters the Citric Acid Cycle in
the matrix of the mitochondria.
The Citric Acid cycle breaks down the Acetyl
Co-A in a series of steps, releasing CO2
It produces 1 ATP, 3 NADH, and 1 FADH2 per
turn.
27. • The Citric Acid cycle (also called the Krebs Cycle)
has eight steps, each catalyzed by a specific
enzyme
• The acetyl group of acetyl CoA joins the cycle by
combining with oxaloacetate, forming citrate
(Citric Acid).
• The next seven steps decompose the citrate
(Citric Acid) back to oxaloacetate, making the
process a cycle
The Citric Acid Cycle
Oxaloacetate + Acetyl CoA Citric Acid
29. • Each Citric Acid Cycle only produces 1 ATP
molecule. The rest of the energy from pyruvate
is in the NADH and FADH2.
• The NADH and FADH2 produced by the Citric
Acid cycle relay electrons extracted from food
to the electron transport chain.
32. Electrons are transferred from NADH or
FADH2 to the electron transport chain
Electrons are passed through a number of
proteins to O2
The chain’s function is to break the large free-
energy drop from food to O2 into smaller steps
that release energy in manageable amounts
33. Electron transfer in the electron transport chain
causes proteins to pump H+
from the
mitochondrial matrix to the intermembrane
space
H+
then moves back across the membrane,
passing through channels in ATP synthase
34. ATP synthase uses the exergonic flow of H+
to
drive phosphorylation of ATP
This is an example of chemiosmosis, the use of
energy in a H+
gradient to drive cellular work
37. During cellular respiration, most energy flows
in this sequence:
glucose → NADH → electron transport chain
→ proton-motive force → ATP
About 40% of the energy in a glucose molecule
is transferred to ATP during cellular
respiration, making about 38 ATP
+ 6 O2 6CO2 + 6H2O + 38 ATP
38. Maximum per glucose: About
36 or 38 ATP
+ 2 ATP+ 2 ATP + about 32 or 34 ATP
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Citric
acid
cycle
2
Acetyl
CoA
Glycolysis
Glucose
2
Pyruvate
2 NADH 2 NADH 6 NADH 2 FADH2
2 FADH2
2 NADH
CYTOSOL Electron shuttles
span membrane
or
MITOCHONDRION
ATP Yield per molecule of glucose at each stage of cellular
respiration:
Notas del editor
Figure 9.2 Energy flow and chemical recycling in ecosystems
Figure 9.5 An introduction to electron transport chains
Figure 9.6 An overview of cellular respiration
Figure 9.6 An overview of cellular respiration
Figure 9.6 An overview of cellular respiration
Figure 9.8 The energy input and output of glycolysis
Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the citric acid cycle
Figure 9.12 A closer look at the citric acid cycle
Figure 9.13 Free-energy change during electron transport
Figure 9.14 ATP synthase, a molecular mill
Figure 9.16 Chemiosmosis couples the electron transport chain to ATP synthesis
Figure 9.17 ATP yield per molecule of glucose at each stage of cellular respiration
