Metabolism & Cellular Respiration

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Metabolism and
Cellular Respiration
AP Biology Rapid Learning Series
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www.RapidLearningCenter.com/
© Rapid Learning Inc. All rights reserved.
AP Biology Rapid Learning Series
Wayne Huang, PhD
Andrew Graham, PhD
Elizabeth James, PhD
Casandra Rauser, PhD
Jessica Habashi, PhD
Sara Olson, PhD
Jessica Barnes, PhD

Learning Objectives
Metabolism.
By completing this tutorial, you will learn about:
Anabolism pathways.
Catabolism pathways.
The energetics of biological
reactions.
The management of cell
resources.
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How cells use cellular
respiration to produce ATP.
Aerobic and anaerobic
respiration.
General Concept Map
Macromolecules
Cell Biology
Metabolism Physiology
Materials for
Structures
used for
A major area
of study in
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Biochemistry
Ecology
BehaviorNutrition
The basis of
studies in Determines

Metabolism Concept Map
Metabolism
Anabolism CatabolismCatabolism
Anabolism
Protein
Anabolism
CarbohydrateCarbohydrate
Anabolism
Catabolism
Protein
CatabolismAnabolism
Lipid
Anabolism
Carbohydrate
Catabolism
Carbohydrate
Catabolism
Anabolism
Lipid
Anabolism
BetaProtein
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Synthesis
Protein
Synthesis
Oxidation
Beta
Oxidation
GlycolysisGlycolysis
Gluconeo-Gluconeo-
genesis
Fatty Acid
Synthesis
Fatty Acid
Synthesis
Respiration
Cellular
Respiration
Breakdown
ote
Breakdown
AerobicAerobic AnaerobicAnaerobic
Metabolism
Building Blocks & Precursors
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Anabolism
Catabolism
The Role of ATP

What is Metabolism?
Metabolism involves the
creation of complex
molecules from simple
M t b li i l th molecules (anabolism).Metabolism is also the
breakdown of complex
molecules into simpler
ones (catabolism).
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Building Blocks From Food
All living organisms get building
blocks for the manufacture of
cellular components from food
and cellular breakdown products.
Carbohydrates
Nucleic Acids Anabolism
Lipids
Proteins
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Catabolism breaks down
molecules into smaller units and
releases energy.
Catabolism Anabolism builds complex
molecules from simple ones
and require energy.

Review: Building Bocks
Nucleotides Amino Acids Mono-
h id
Fatty
Nucleic Acids
CarbohydratesProteins Lipids
saccharides Acids
These are the precursors for
the cells building blocks.
Precursors are molecules that when assembled
become one of the major building blocks of the cell.
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The four organic building blocks
are made from precursors.
Precursors come from the breakdown
of food & cell components.
Stages of Anabolism
Anabolism is the set of metabolic
processes that require energy,
released from catabolism, to build
complex molecules.
1) Precursors are produced: amino
acids, monosaccharides,
i id d l id
complex molecules.
Anabolism has three stages.
2) Precursors are activated using
energy from ATP to become
reactive.
isoprenoids and nucleotides.
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3) The reactive precursors are assembled
into complex molecules like proteins,
polysaccharides, lipids and nucleic acids.

Anabolism Examples
Organisms have differing
types of molecules that
they can make themselves.
Autotrophs like plants canAutotrophs, like plants can
make complex molecules
like polysaccharides and
proteins from simple
molecules like CO2 and H2O.
Heterotrophs need a source of
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complex substances like
monosaccharides and amino
acids to make complex
molecules.
“Trophs” Flow Sheet
Don’t know how to tell if an
organism is a autotroph or
heterotroph?
Follow this flow /
decision chart to
determine the
“troph” of an
organisms.g
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Catabolism
Monosaccharide
Catabolism is the breakdown of
complex molecules (polymers)
thereby releasing energy.
Polysaccharide
Fatty Acids
Nucleotides
Adenosine triphosphate
is the energy storage
molecule.
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Amino Acids
ProteinNucleic Acid polymer (DNA)
Catabolism and Waste
Acetic Acid
AmmoniaPolymers
Lactic Acid
Acetic Acid
Urea
Carbon Dioxide
Monomers
Degraded To
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Waste Products
Cells use monomers to make new polymers or degrade monomers
further making a variety of waste products and releasing ATP.
ATP

Anabolism vs. Catabolism
Anabolism Catabolism
When do cells perform anabolism or catabolism?
Create new
structures
and enzymes
Break down
food
Store unused
nutrients for
later use
Destroy old
structures for
recycling
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Excess Resources Deficient Resources
Feeding Period
Rest Event
Fasting Period
Stress Event
Energetics of Biological
Reactions
Energy
Thermodynamics
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Thermodynamics
Activation Energy & Enzymes
Redox Reactions
The Role of ATP in Metabolism
Coupling

What is Biological Thermodynamics?
Bioenergetics is the
study of energy
transformation in
biological systems.
It is a quantitative study of
energy transductions in living
organisms and the chemical
processes involved.
Energy is the ability
to do work or
supply heat.
Work is the transfer
of energy from one
t t th
Living cells and
organisms must
f k
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system to another.perform work to
live, grow and
reproduce.
First Law of Thermodynamics
The total energy of a
system and its
surroundings is constant.
Energy can take different
forms: heat, motion etc.
Energy cannot be created
or destroyed.
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Kinetic energy may manifest
as heat.
And potential energy is the
amount of energy possible.

Meaning of the First Law
The First Law of ThermodynamicsThe First Law of Thermodynamics
requires that all energy released
in chemical bond formation
observe the following:
Must be used to break other
bonds.
Released as heat
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Released as heat.
Stored in some other form.
Second Law of Thermodynamics
Ice - Low Entropy Water - Medium
Entropy
Steam - Maximum
Entropy
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Ice consists of
highly ordered
water molecules.
When the ice melts
the water molecules
become disordered
relative to ice.
Maximum disorder
when water is
heated and turns
into steam.

Metabolism - Introduction
Living organisms are not at
equilibrium. They require a
continuous influx of free
energy to maintain order in a
universe where there is
By coupling the exergonic (energy
releasing) reactions of nutrient
oxidation and endergonic (energy
consuming) reactions, they
universe where there is
maximum disorder.
maintain the living state.
Metabolism is the overall
process through which
free energy is acquired
and utilized by living
systems to carry out their
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systems to carry out their
various functions.
Coupling of Reactions
A
B
A
B + C
D
C + D
∆Go’ = +5 kcal/mol
∆Go’ = -8 kcal/mol
∆Go’ = -3 kcal/mol
Overall free energy
change for chemically
coupled series of
reactions is equal to
the sum of the free
Under standard conditions:
A can not be spontaneously converted into B and C,
because ∆G is positive.
Conversion of B into D under standard conditions is
thermodynamically feasible.
As free energy changes are additive, the conversion of
the sum of the free
energy changes of the
individual steps.
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A into C and D has a ∆Go‘ of -3 kcal/mol. It means that it
can occur spontaneously under standard conditions.
A thermodynamically unfavorable reaction can be
driven by a thermodynamically favorable reaction that is
coupled to it.
In this example, the reactions are coupled by the shared
chemical intermediate B.

Glycolysis & Thermodynamics
ADP
ATP
∆G°‘= -31 kJoules/mol
∆G°‘= +14 kJoules/mol
Glucose-6-phasphateGlucose
First reaction in glycolysis: making glucose-6-phosphate from glucose.
The hydrolysis of ATP to ADP provides the energy by thermodynamic
coupling.
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ATP + H20 ↔ ADP + Pi ∆G°‘= -31 kJoules/mol
Pi + glucose ↔ glucose-6-phospate + H20 ∆G°‘= +14 kJoules/mol
Coupled Reactions:
ATP + glucose ↔ glucose-6-phosphate + ADP
Net Energy Change ∆G°‘= -17 kJoules/mol
Enzymes Affect Reaction Rates
Enzymes are catalysts affecting only the rate of
product formation.
Enzymes affect the rate of reaction by lowering the
activation energy.
Reaction kinetics without
enzyme
E
Substrate
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Reaction with
enzyme
Energy
BarrierLowering of
activation energy
by enzymes
Products

Oxidation – Reduction Reactions
Oxidation – Reduction Reactions
(Redox)
In redox reactions electrons are
transferred from an electron donor
Living things get most of their free
energy from redox reactions. In
photosynthesis, CO2 is reduced and
Fe3+ + Cu+ Fe2+ + Cu2+
(reductant or reducing agent) to an
electron acceptor (oxidant or
oxidizing agent).
p y 2
H2O is oxidized to yield
carbohydrates and O2.
Cu+, the reductant is oxidized to Cu2+ while
Fe3+, the oxidant, is reduced to Fe2+.
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Fe3+ + e- Fe2+ (Reduction)
Cu+ Cu2+ + e- (Oxidation)
Redox reactions may be divided into two
half-reactions or redox couples, such as
Redox Potential
Redox potential is the
tendency of the solution to
either gain or loose electrons.
Redox potential (E0) is a
quantitative measure of the
tendency of redox pair to
loose or gain electrons.
These are some standard redox
values for biologically
i t t l l
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important molecules.
System Eo volts
NAD+ /NADH -0.32
Oxygen / Water +0.82

This ATP then can be used
for anabolic processes
ATP Production & Destruction
Anabolism uses ATP. Catabolism produces ATP.
for anabolic processes.
ADP + PiATP
Anabolism
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Catabolism releases energy which
can be used to produce ATP.
Catabolism
Respiration
Glycolysis
Krebs Cycle
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Krebs Cycle
Oxidative Phosphorylation
Fermentation

Cellular respiration is a
term used to describe
the collective metabolic
reactions and processes
Aerobic respiration
includes: glycolysis,p
that a cell used to get
energy from molecules.
g y y
oxidative
decarboxylation of
pyruvate, TCA and
oxidative
phosphorylation.
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And for those processes
that don’t use oxygen there
is anaerobic respiration.
Energy Coupling & ATP Formation
Pyruvate Kinase
Breakdown of PEP to pyruvate releases energy and phosphate.
This reaction is coupled with the production of ATP from ADP.
Energy is needed to make ATP. ATP is
produced by coupling energy from an
Phosphoenolpyruvate Pyruvate
ADP ATP
Pyruvate Kinase
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produced by coupling energy from an
energy releasing reaction to run an
energy requiring reaction.

Aerobic VS Anaerobic Respiration
Glucose
Cellular respiration can either be aerobic or
anaerobic.
Cellular respiration can take two paths.
Glucose
Anaerobic
Respiration
Oxygen
?
anaerobic.
No
Yes
ATP
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Aerobic
Respiration
Yes
Aerobic means “with oxygen” and
anaerobic means “without oxygen.”
ATP
Respiration: Aerobic vs. Anaerobic
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Aerobic Respiration:
1) Glycolysis
2) Krebs Cycle
3) Oxidative Phosphorylation
Anaerobic Respiration:
1) Glycolysis
2) Fermentation

Aerobic: Oxygen Final e- Acceptor
When oxygen is available, aerobic respiration transports electrons
down a chain to create a concentration gradient.
This gradient powers a motor to produce a large number of ATP.
Step 1: Glycolysis is the entry point
and produces 2 ATP.Glycolysis
Krebs
Step 2: The Krebs Cycle prepares
electron carriers for delivery and
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Oxidative
Phosphorylation
Cycle
electron carriers for delivery and
produces 2 ATP.
Step 3: Oxidative Phosphorylation
creates a concentration gradient to
produce 32 ATP.
Glycolysis Definition
Glucose
Pyruvate
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Glycolysis is the set of reactions that converts glucose into
pyruvate while producing a small amount of ATP (energy).
Adenosine 5'-triphosphate (ATP)

Glycolysis: 2NADH, 2ATP, Pyruvate
Glucose
Glucose 6-phosphate
ATP 1
2
Fructose 6-phosphate
Fructose 1,6-phosphate
Glyceraldehyde 3-phospate
1,3-diphosphoglycerate
P2 NADH2
2X
2X
3
4
5
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, p p g y
3-phosphoglycerate
2-phosphoglycerate
phosphoenolpyruvate
pyruvate
ATP2
ATP2
2X
2X
2X
6
7
8
9
Electron Transport Chain
Electron transport chain is
also known as the electron
transport system (ETS).
It is a series of membrane
associated electron
carriers involved in
transporting electrons
produced during
biochemical reactions that
make ATP.
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The two sources of energy
available to living
organisms: oxidation-
reduction redox reactions
and photosynthesis.

Citric Acid Cycle
Citric acid cycle is also
called the tricarboxylic
acid cycle (TCA).
So there are four metabolic
pathways involved in
carbohydrate catabolism
and ATP production.
TCA is involved in the conversion of
carbohydrates, fats and proteins into
carbon dioxide, water and energy.
The four pathways are: TCA
cycle, glycolysis, pyruvate
oxidation, and respiratory
chain.
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TCA cycle is a series of
enzyme catalyzed reactions
that use oxygen as part of
cellular respiration.
The Krebs Cycle
The products of the first turn
of the TCA cycle are 1 GTP, 3
NADH, 1 FADH2 and 2CO2.
2 Acetyl-CoA molecules are
made from every glucose
molecule so two turns of the
TCA cycle are required for
every glucose moleculeevery glucose molecule.
That’s right so at the end of
all the cycles the total
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y
products per glucose
molecule is: 2 GTP, 6 NADH,
2 FADH2 and 4 CO2.

Oxidative Phosphorylation = 32 ATP
This is a schematic of a
mitochondria. Look
closely at its various
membranes. And theOxidative phosphorylation
creates a proton gradient that location of the TCA.creates a proton gradient that
is used to generate the 32 ATP.
NADH and FADH2 from TCA
cycle unload their electrons
and pass them to the
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and pass them to the
membrane bound protein
machines I, II, III, IV.
The electrons are passed down an electron transport
chain to oxygen as the final electron acceptor.
TCA & ETC
Mitochondria
In eukaryotes TCA / ETC cycle
takes place in the mitochondria.
In prokaryotes the TCA cycle
occurs in the cytoplasm.
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The cycle requires the
presence of oxygen.
Intermediates can also act as a
precursors to many other
biosynthetic pathways.
Lost intermediates are
replenished by anaplerotic
reactions.

Summary: Aerobic Respiration
Glycolysis Krebs Cycle
Oxidative
Phosphorylation
1. Glucose is
b k d
1. Acetyl CoA
li
1. NADH and
FADHbroken down
into pyruvate.
2. Energy
Production
Total: 2 ATP.
runs a cyclic
reaction
which
produces
NADH and
FADH2
2. CO2 is
produced as
FADH2 pass
electrons down
chain which
pumps H+ to
create gradient.
2. H+ gradient
flows to power
ATP synthase.
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waste.
3. Energy
Production
Total: 2 ATP.
3. Energy
Production Total:
32 ATP.
Anaerobic Respiration
Anaerobic respiration occurs when there is an
energy requirement but no oxygen.
Anaerobic respiration runs glycolysis repeatedly.
Step 1: Glycolysis is the entry point
and produces 2 ATP.
Glycolysis
Anaerobic respiration runs glycolysis repeatedly.
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Step 2: Fermentation regenerates
reactants needed for the glycolysis
reaction to proceed again.
Fermentation

Fermentation
Fermentation is respiration under
anaerobic conditions with no
external electron acceptor.
Fermentation does not have to be
in an anaerobic environment.
Yeast cells even in the presence of
oxygen, prefer fermentation top yg , p
oxidative phosphorylation if
sugars are available.
Sugars are the
common
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common
substrate of
fermentation and
typical products
are: ethanol,
lactic acid and
hydrogen.
In muscle under
intense exercise
with no external
electron
acceptors lactic
acid is produced.
Summary: Anaerobic Respiration
Glycolysis Fermentation
1. Glucose is 1. Pyruvate is
broken down
into pyruvate.
2. Production of
2 ATP.
used to
regenerate
intermediates
of glycolysis.
2. Glycolysis
begins anew.
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ATP Production Totals
Aerobic Respiration vs. Anaerobic Respiration.
ATP MadeAerobic
2+ Krebs Cycle
Glycolysis 2
= Grand Total 36
+ 32+ Oxidative Phosphorylation
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0+ Fermentation
ATP Made
Glycolysis 2
= Grand Total 2
Anaerobic
Question: Review
An exergonic reaction _______
energy.
___________releases
endergonic
______ reactions are energy
i ___________
___________
endergonic
glycolysis
consuming.
Glycolysis, TCA cycle,
oxidative decarboxylation of
pyruvate and oxidative
Glucose is broken down into
pyruvate in what pathway?
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___________Cellular Respirationpyruvate, and oxidative
phosphorylation.
____ a set of metabolic
pathways that require energy
to build complex molecules
from simple one.
___________Anabolism

The steps of aerobicThe steps of aerobic
Metabolism is all of
the chemical
Metabolism is all of
the chemical
The steps of
anaerobic respiration
are: glycolysis and
lactic acid
The steps of
anaerobic respiration
are: glycolysis and
lactic acid
Learning Summary
Cellular respiration powers theCellular respiration powers the
The steps of aerobic
respiration are:
glycolysis, the Krebs
Cycle, and oxidative
phosphorylation.
The steps of aerobic
respiration are:
glycolysis, the Krebs
Cycle, and oxidative
phosphorylation.
reactions in a cell
and thus the entire
organism.
reactions in a cell
and thus the entire
organism.
lactic acid
fermentation.
Anaerobic respiration
does not produce
much ATP.
lactic acid
fermentation.
Anaerobic respiration
does not produce
much ATP.
Anabolism is the constructionAnabolism is the construction
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Cellular respiration powers the
cell by producing ATP from the
breakdown of sugar. Aerobic
respiration occurs when there
is oxygen whereas anaerobic
is not.
Cellular respiration powers the
cell by producing ATP from the
breakdown of sugar. Aerobic
is oxygen whereas anaerobic
is not.
Anabolism is the construction
of complex molecules
whereas catabolism is the
molecules. Anabolism
requires energy whereas
catabolism releases energy.
Anabolism is the construction
of complex molecules
whereas catabolism is the
molecules. Anabolism
requires energy whereas
catabolism releases energy.
Congratulations
You have successfully completed
the core tutorial
Metabolism and Cellular
Respiration
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Respiration

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Metabolism & Cellular Respiration

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