Download Cellular Respiration - Cathedral High School

BIOLOGY
Chapter 8: pp. 133-149
10th Edition
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
NADH
e–
Insert figure 8.2 here
NADH
e–
e–
e–
Cytoplasm
e–
NADH and
FADH2
e–
Glycolysis
glucose
Mitochondrion
e–
Citric acid
cycle
Preparatory reaction
pyruvate
Sylvia S. Mader
Cellular Respiration
Electron transport
chain and
chemiosmosis
2 ADP
2 ADP
4 ATP total
4 ADP
2
ATP
net gain
2 ADP
2
ATP
32 ADP
or 34
32
or 34
ATP
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
1
Connection between Photosynthesis and Respiration
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
STAGES OF CELLULAR RESPIRATION AND
FERMENTATION
Fermentation = anaerobic
Cellular respiration = aerobic
• Cellular respiration oxidizes sugar and
produces ATP in 3-4 main stages: Glycolysis,
Prep (Transition) Stage, Kreb’s (Citric Acid)
Cycle, ETC
• Fermentation oxidizes sugar and does not
produce ATP, but yields a constant supply of
NAD+ (an electron carrier)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Glucose Breakdown: Summary Reaction
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Oxidation
C6H12O6
+
6O2
6CO2
+
6H2O
+
energy
glucose
Reduction
 Electrons
are removed from substrates and
received by oxygen, which combines with
H+ to become water.
 Glucose
is oxidized and O2 is reduced
4
NAD+ and FAD
NAD+ (nicotinamide adenine dinucleotide)



Called a coenzyme of oxidation-reduction. It can:

Oxidize a metabolite by accepting electrons

Reduce a metabolite by giving up electrons
Each NAD+ molecule used over and over again
FAD (flavin adenine dinucleotide)

Also a coenzyme of oxidation-reduction

Sometimes used instead of NAD+

Accepts two electrons and two hydrogen ions (H+) to
become FADH2
5
Cellular Respiration
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
O2 and glucose enter cells,
which release H2O and CO2.
H2 O
CO2
intermembrane
space
cristae
Mitochondria use
energy from
glucose to form ATP
from ADP + P .
ADP +
P
ATP
© E. & P. Bauer/zefa/Corbis; (Bread, wine, cheese, p. 139): © The McGraw Hill Companies, Inc./John Thoeming, photographer; (Yogurt, p. 139): © The McGraw Hill Companies,
Inc./Bruce M. Johnson, photographer
6
ATP
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Phases of Cellular Respiration

Cellular respiration includes four phases:

Glycolysis is the breakdown of glucose into
two molecules of pyruvate
Occurs in cytoplasm
 ATP is formed
 Does not utilize oxygen


Transition (preparatory) reaction
Both pyruvates are oxidized and enter mitochondria
 Electron energy is stored in NADH
 Two carbons are released as CO2 (one from each
pyruvate)

7
Phases of Cellular Respiration

Citric acid cycle
Occurs in the matrix of the mitochondrion and
produces NADH and FADH2
 In series of reaction releases 4 carbons as CO2
 Turns twice (once for each pyruvate)
 Produces two immediate ATP molecules per
glucose molecule


Electron transport chain
Extracts energy from NADH & FADH2
 Passes electrons from higher to lower energy states
 Produces 32 molecules of ATP

8
Glucose Breakdown: Overview of 4 Phases
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
NADH
e–
e–
NADH
e–
e–
Cytoplasm
e–
NADH and
FADH2
e–
Glycolysis
glucose
Mitochondrion
e–
Citric acid
cycle
Preparatory reaction
pyruvate
Electron transport
chain and
chemiosmosis
2 ATP
2 ATP
4 ATP total
4 ADP
2
ATP
net gain
2 ADP
2
ATP
32 ADP
or 34
32
or 34
ATP
9
Glucose Breakdown: Glycolysis

Occurs in cytoplasm outside mitochondria
 Energy Investment Steps:



Two ATP are used to activate glucose
Glucose splits into two G3P molecules
Energy Harvesting Steps:





Oxidation of G3P occurs by removal of electrons and
hydrogen ions
Two electrons and one hydrogen ion are accepted by
NAD+ resulting two NADH
Four ATP produced by phosphorylation
Net gain of two ATP
Both G3Ps converted to pyruvates
10
First phase in aerobic respiration is
GLYCOLYSIS….no oxygen involved in this
phase
Glycolsis
Glucose
Pyruvate
Mitochondrion
ATP
Substrate-level
phosphorylation
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Details of
glycolysis...
...Do we
need to
know
that??!!
Steps 1 – 3 A fuel
molecule is energized,
using ATP.
Glucose
Step
PREPARATORY
PHASE
(energy investment)
1
Glucose-6-phosphate
2
Fructose-6-phosphate
3
Step 4 A six-carbon
intermediate splits into two
three-carbon
intermediates.
Step 5 A redox
reaction generates
NADH.
Fructose-1,6-diphosphate
4
Glyceraldehyde-3-phosphate
(G3P)
6
Steps 6– 9 ATP
and pyruvic acid
are produced.
ENERGY PAYOFF
PHASE
5
1,3-Diphosphoglyceric acid
(2 molecules)
7
3-Phosphoglyceric acid
(2 molecules)
8
2-Phosphoglyceric acid
(2 molecules)
2-Phosphoglyceric acid
(2 molecules)
9
Figure 6.9B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Pyruvic acid
(2 molecules
per glucose molecule)
GLYCOLYSIS BASICS
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html
Glucose
Figure 6.9A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Pyruvic
acid
Glycolysis: Inputs and Outputs
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
inputs
Glycolysis
outputs
glucose
2 pyruvate
2 NADH
2 NAD+
2
ATP
2 ADP
4 ADP + 4 P
4 ATP total
2
ATP
net gain
11
Pyruvate
Pyruvate is a pivotal metabolite in cellular
respiration
 If O2 is not available to the cell,
fermentation, an anaerobic process,
occurs in the cytoplasm.



During fermentation, glucose is incompletely
metabolized to lactate, or to CO2 and alcohol
(depending on the organism).
If O2 is available to the cell, pyruvate enters
mitochondria by aerobic process.
16
Fermentation
An anaerobic process that reduces pyruvate to either
lactate or alcohol and CO2
NADH passes its electrons to pyruvate
Alcoholic fermentation, carried out by yeasts,
produces carbon dioxide and ethyl alcohol




Lactic acid fermentation, carried out by certain
bacteria and fungi, produces lactic acid (lactate)



Used in the production of alcoholic spirits and breads.
Used commercially in the production of cheese, yogurt, and
sauerkraut.
Other bacteria produce chemicals anaerobically,
including isopropanol, butyric acid, proprionic acid, and
acetic acid.
17
Fermentation is an anaerobic alternative to
aerobic respiration
• Under anaerobic
conditions, many
kinds of cells can
use glycolysis alone
to produce small
amounts of ATP
– But a cell must have
a way of
replenishing NAD+
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
ALCOHOLIC FERMENTATION
• In alcoholic fermentation, pyruvic acid is
converted to CO2 and ethanol
– This recycles NAD+ to keep glycolysis working
released
GLYCOLYSIS
Glucose
2 Pyruvic
acid
Figure 6.15A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
2 Ethanol
Figure 6.15C
LACTIC ACID FERMENTATION
• In lactic acid fermentation, pyruvic acid is
converted to lactic acid
– As in alcoholic fermentation, NAD+ is recycled
• Lactic acid fermentation is used to make
cheese and yogurt
GLYCOLYSIS
Glucose
2 Pyruvic
acid
Figure 6.15B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
2 Lactic acid
Efficiency of Fermentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fermentation
inputs
glucose
2 ADP + 2
P
2
outputs
2 lactate or
2 alcohol and 2
CO2
ATP
net gain
25
Pyruvic acid is chemically groomed for the Krebs
cycle in the Transition or Prep Stage
• Each pyruvic acid molecule is broken down to
form CO2 and a two-carbon acetyl group, which
enters the Krebs cycle
Pyruvic
acid
Acetyl CoA
(acetyl coenzyme A)
CO2c
Figure 6.10
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Aerobic Respiration Continues in
the Mitochondria
Glycolsis
Glucos
e
Citric
acid
cycle
Pyruvate
Mitochondrion
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Details of the Kreb’s Cycle…….
Do we need to know all that????
Answer: Yes and No
2 carbons enter cycle
Oxaloacetic
acid
1
Citric acid
CO2 leaves cycle
5
KREBS
CYCLE
2
Malic
acid
4
Alpha-ketoglutaric acid
3
CO2 leaves cycle
Succinic
acid
Step 1
Acetyl CoA stokes
the furnace
Steps 2 and 3
NADH, ATP, and CO2 are generated
during redox reactions.
Figure 6.11B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Steps 4and 5
Redox reactions generate FADH2
and NADH.
Let’s look at a simplified version of the
Kreb’s Cycle first…..
The Krebs cycle completes the
oxidation of glucose,
generating many NADH and
FADH2 molecules
The Krebs cycle is a series
of reactions in which
enzymes strip away
electrons and H+ from each
acetyl group
What are the products of
the Kreb’s cycle?
Figure 6.11A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Acetyl CoA
KREBS
CYCLE
2
CO2
KREB’S CYCLE
aka Citric Acid Cycle…….times 2….WHY?
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_2_
.html
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Oxidative Phosphorylation =
ETC plus Chemiosmosis
Electrons
carried
via NADH
Electrons carried
via NADH and
FADH2
Citric
acid
cycle
Glycolsis
Glucose
Pyruvate
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Mitochondrion
ATP
Substrate-level
phosphorylation
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
ATP
Substrate-level
phosphorylation
ATP
Oxidative
phosphorylation
Chemiosmosis powers most ATP production
http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter25/animation__electron_transport_system_and_atp_synthesis__quiz_2_.html
• The electrons from NADH
and FADH2 travel down the
electron transport chain
(slowly losing energy). They
will be grabbed by oxygen
• Energy released by the
electrons is used to pump
H+ into the space between
the mitochondrial
membranes
• In chemiosmosis, the H+
ions diffuse back through
the inner membrane
through ATP synthase
complexes, which capture
the energy to make ATP
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Therefore, the two mechanisms that generate ATP
are ETC and Chemiosmosis
• Cells use the energy
released by “falling”
electrons to pump
H+ ions across a
membrane
– The energy of the
gradient is
harnessed to make
ATP by the process
of chemiosmosis
High H+
concentration
Membrane
Electron
transport chain
ATP
synthase
Energy from
Low H+
concentration
Figure 6.7A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
ATP synthase
uses graient
energy to make
ATP
Overview of Cellular Respiration
(Aerobic)
6
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
INTERCONNECTIONS BETWEEN
MOLECULAR BREAKDOWN AND SYNTHESIS
Cells use many kinds of organic molecules as fuel
for cellular respiration
• Polysaccharides can be hydrolyzed to
monosaccharides and then converted to glucose
for glycolysis
• Proteins can be digested to amino acids, which
are chemically altered and then used in the
Krebs cycle
• Fats are broken up and fed into glycolysis and
the Krebs cycle
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Pathways of molecular breakdown
Food, such as
peanuts
Polyscaccharides
Fats
Proteins
Sugars
Glycerol Fatty acids
Amino acids
Amino
groups
Glucose
G3P
Pyruvic
acid
Acetyl
CoA
GLYCOLYSIS
Figure 6.16
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
KREBS
CYCLE
ELECTRON
TRANSPORT CHAIN
AND CHEMIOSMOSIS
The fuel for respiration ultimately comes from
photosynthesis
• All organisms have the ability to harvest
energy from organic molecules
– Plants, but not animals,
can also make these
molecules from inorganic
sources by the process of
photosynthesis (Chapter 7)
Figure 6.18
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings