Transcript Metabolism and Energy

Metabolism
Photosynthesis
Cellular Respiration
Chapters 8-10
Metabolism and Energy
 Metabolism
 Catabolism
 Anabolism
 Bioenergetics
 Energy
 Kinetic
 Heat/Thermal
 Light Energy
 Potential
 Chemical
Organisms are energy
transformers!
Metabolism and Energy
 Metabolism
Organisms are energy
transformers!
 Metabolic pathway begins with a
specific molecule, which is then
altered in a series of defined steps
leading to a specific product
 Each step is catalyzed by a
specific enzyme
Metabolism and Energy
 Metabolism
Organisms are energy
transformers!
 Catabolism
 Energy released (helps to drive
anabolic pathways).
 Ex: cellular respiration
 sugar put in to the body is broken
down to do work in the cell
(movement, active transport, etc).
Metabolism and Energy
 Metabolism
Organisms are energy
transformers!
 Catabolism
 Anabolism
 sometimes called biosynthetic
pathways-
 Ex: synthesis of a protein from
amino acids.
 Energy required/absorbed.
Metabolism and Energy
 Metabolism
 Catabolism
Organisms are energy
transformers!
 Anabolism
 Bioenergetics
 the study of how energy flows through
living systems.
Metabolism and Energy
 Metabolism
 Catabolism
 Anabolism
Organisms are energy
transformers!
 Bioenergetics
 Energy
 the capacity to cause change.
 Some forms of energy can be used to do
work- or move matter against opposing
forces
 Ex: (friction and gravity)
 Ability to rearrange a collection of
matter
Metabolism and Energy
 Energy
Organisms are energy
transformers!
 Kinetic
 Relative motion of objects
 moving objects can perform
work by imparting motion to
other matter.
 Ex: Moving water through a dam
turns turbines, moving bowling
ball knocks over pins
Metabolism and Energy
Organisms are energy
transformers!
 Energy
 Kinetic
 Heat/Thermal
 comes from the movement of
atoms or molecules associated
with kinetic energy
Metabolism and Energy
Organisms are energy
transformers!
 Energy
 Kinetic
 Heat/Thermal
 Light Energy
Type of energy that can be harnessed
to perform work
Ex. Powering Photosynthesis
Metabolism and Energy
 Kinetic
Organisms are energy
transformers!
 Heat/Thermal
 Light Energy
 Potential
 Non-kinetic energy
 because of location or
structure, height, chemical
bonds, etc.
Metabolism and Energy
 Kinetic
 Heat/Thermal
 Light Energy
Organisms are energy
transformers!
 Potential
 Chemical
 the potential energy available for
release by a reaction.
 Ex: Glucose is high in chemical
energy and the process of
glycolysis breaks it down. As bonds
are broken, energy is released, but
bonds also reform to make new
molecules, thus it uses some
energy.
Metabolism and Energy
Organisms are energy
transformers!
All original energy comes
from light.
(photosynthesis- primary
producer- consumerwho changes it from
chemical to kinetic and
releases thermal.
Thermodynamics
 What is Thermodynamics?
Thermodynamics
 The energy transformations that occur in a
collection of matter
Thermodynamics
 Thermodynamics
 System vs. Surroundings
 Isolated System vs. Open System
 First Law of Thermodynamics
Thermodynamics
 Two Laws of Thermodynamics govern
energy exchange:
 First Law of Thermodynamics
 Second Law of Thermodynamics
Thermodynamics
 Two Laws of Thermodynamics govern
energy exchange:
 First Law of Thermodynamics
 energy cannot be created or destroy Only transferred or transformed
 Known as Principle of conservation of energy
Thermodynamics
 Second Law of Thermodynamics
 During energy transfer, some energy
become unusable energy (unavailable to
do work)
 Entropy (S) – Measure of disorder or
randomness
Thermodynamics
 So, What is the Second Law of
Thermodynamics?
 Every energy transfer or transformation increases
the entropy of the universe
Thermodynamics
 Spontaneous (Energetically Favorable) vs.
Nonspontaneous Processes
 Leads to the second way we state the 2nd Law
of Thermodynamics:
 For a process to occur spontaneously, it must
increase the entropy of the universe
Think-Pair-Share
 How does the second law of
thermodynamics help explain the diffusion
of a substance across a membrane?
 If you place a teaspoon of sugar in the
bottom of a glass of water, it will dissolve
completely over time. Left longer,
eventually the water will disappear and the
sugar crystals will reappear. Explain these
observations in terms of entropy.
Gibbs Free Energy
 Free Energy
 Portion of system’s energy that can perform work when
temp and pressure are uniform throughout system
 ΔG = free energy of a system

-ΔG = spontaneous reaction

+ΔG = nonspontaneous reaction

ΔG = 0 = Dead Cell (can do no work)
ΔG = ΔH – TΔS
ΔG = ΔGfinal – ΔGinitial
 Enthalpy
Gibbs Free Energy
ΔG = ΔH – TΔS
ΔG = ΔGfinal – ΔGinitial
 ΔH = he change in the system’s enthalpy
 What is enthalpy?
 Total energy
 ΔS = change in system’s entropy
 T = absolute Temperature in Kelvin
Gibbs Free Energy
 Endergonic vs. Exergonic Reactions
+ΔG
Non-Spontaneous
-ΔG
Spontaneous
Warm Up Exercise
 Glow in the dark necklaces are snapped in
a way that allows two chemicals to mix and
they glow. Is this an endergonic or
exergonic reaction? Explain.
 In simple diffusion, H+ ions move to an equal
concentration on both sides of a cell
membrane. In cotransport, H+ ions are
pumped across a membrane to create a
concentration gradient. Which situation
allows the H+ ions to perform work in the
system?
ATP and Cellular Work
 Three Types of Work
 Chemical
 Transport
 Mechanical
 Energy Coupling
 Phosphorylated
Intermediate
ATP Hydrolysis
 kh
ATP and Cellular Work
ATP Cycle
 The body regenerates 10 million molecules
of ATP per second per cell!
Flashback
 Name the four major
macromolecules and their monomers.
Enzymes
 Enzymes- biological catalyst
 Substrates
Enzymes
 Activation Energy (EA)
Enzymes
 Enzymes catalyze reactions by lowering the
activation energy.
Enzymes
 Enzyme + Substrate = Enzyme-Substrate Complex
Enzyme
+
Substrate(s)
EnzymeSubstrate
Complex
Enzyme
+
Product(s)
Enzymes
 Active Site
 Induced Fit
Warm Up Exercise
 Explain the affect that enzymes have on
activation energy.
 What is a substrate?
 Describe what is meant by induced fit.
Effects of Environment
 Temperature
 pH
 Concentration of Enzyme
 Concentration of Substrate
Enzymes
 Cofactors
 Coenzyme
Enzyme Action
 Competitive Inhibitors
 Noncompetitive Inhibitors
Allosteric Regulation
Cooperativity
 Cooperativity
Feedback Inhibition
Warm Up Exercise
 Explain the difference between competitive
and noncompetitive inhibitors
 Describe the negative feedback
demonstrated by ATP/ADP.
Cellular Respiration
Cellular Respiration
 Cell respiration is a catabolic pathway.
 Aerobic Cellular Respiration
 Anaerobic Cellular Respiration (aka:
Fermentation)
Redox Reactions
 Reduction vs. Oxidation
 Why are carbs and fats the best molecules
for energy?
 Why must glucose be broken down in a
series of steps rather than one quick
reaction?
Electron Transport
 Dehydrogenase- removes electrons from
glucose (or other substrate) transferring them
to its coenzyme (NAD+) which is reduced to
NADH. (NADH = potential energy)
 NAD+ (nicotinamide adenine dinucleotide)-
an electron carrier.
 Cycles between NAD+ and NADH
NAD to NADH
Electron Transport
 As glucose is broken down (in many small
reactions) electrons are shuttled (by NADH)
down the Electron Transport Chain (ETC).
 Ultimately, oxygen is the final electron
acceptor.
Warm Up Exercise
 What is the function of NAD+?
 Explain the terms oxidation and reduction.
 What is the difference between aerobic
and anaerobic respiration?
Stages of Respiration
 Glycolysis (in cytoplasm)- can occur with
our without oxygen.
 Pyruvate Oxidation (in mitochondria)
 Citric Acid Cycle (in mitochondria)
 Oxidative Phosphorylation: Electron
Transport Chain and Chemiosmosis (in the
outer membrane of the mitochondria)
Stages of Respiration
 asdklf
ADP to ATP
 Oxidative Phosphorylation- inorganic
phosphate is added to ADP to produce ATP.
 Occurs in ETC and chemiosmosis.
 Substrate-Level Phosphorylation- an enzyme
transfers a phosphate group from a
substrate molecule to ADP to form ATP.
 Occurs in glycolysis and citric acid cycle.
 Substrate = an organic molecule generated
as an intermediate in glycolysis.
 kjh
Warm Up Exercise
 Without using your notes, name the four
major processes of cellular respiration and
where in the cell they occur.
 Explain the difference between oxidative
and substrate-level phosphorylation.
Oxidative Phosphorylation
 Pyruvate enters mitochondria (via active
transport) and is converted to Acetyl CoA
Citric Acid/
Kreb’s Cycle
Citric Acid/Kreb’s Cycle
 Acetyl CoA (from oxidative phosphorylation)
enters the Citric Acid cycle and combines
with oxaloacetate to form citrate, the
ionized form of citric acid.
Warm Up Exercise
 Walk through the Kreb’s cycle, stating the
reactants and the products and where they
came from, or go to
ETC
 Cytochromes-
electron carriers
in ETC. They are
proteins with a
Heme group
attached.
 Represent a
series of redox
reactions.
Chemiosmosis
 Chemiosmosis- energy
coupling mechanism
that uses H+ gradient to
drive cellular work.
 ATP Synthase- enzyme
that makes ATP from
ADP in the inner
membrane of
mitochondria.
Chemiosmosis
 Proton Motive Force- the H+ gradient that
results from the pumping of H+ ions from the
matrix of the mitochondria to the
intermembrane space.
 kjh
Energy Totals
 Kh;
Warm Up
-Cell Resp Challenge Why does NADH have more energy than
FADH2?
 Explain the idea of energy coupling that
occurs in chemiosmosis.
 What element (atom) helps to pull electrons
down the ETC?
 How many total ATPs are produced per
molecule of glucose in aerobic respiration?
Alternatives to
Aerobic Respiration
 Anaerobic Respiration- uses ETC with a
different final electron receptor (besides
oxygen)
 Fermentation- no ETC. Glycolysis followed
by a fermentation process.
 Two main types: Alcoholic and Lactic Acid
Fermentation
 Alcoholic Fermentation- pyruvate is
converted to acetaldehyde then to ethanol
(ethyl alcohol). CO2 byproduct.
Fermentation
 Lactic Acid Fermentation- pyruvate is
reduced by NADH to form lactate, with no
release of CO2.
Aerobic vs. Anaerobic
 Obligate Anaerobes-
organisms that cannot
survive in the presence
of oxygen.
 Carry out only
fermentation or
anaerobic respiration.
 Facultative Anaerobes-
organisms that can
survive using
fermentation or
respiration.
Warm Up Exercise
 A glucose-fed yeast cell is moved from an
aerobic environment to an anaerobic one.
How would its rate of glucose consumption
change if ATP were to be generated at the
same rate?
Photosynthesis
 Mesophyll-
tissue in the
interior of the
leaf. Where
chloroplasts
are found.
 Stomata-
microscopic
pores in the
leaf that allow
CO2 and O2
enter and exit.
Photosynthesis
 The O2 given off in photosynthesis comes
from H2O, not CO2.
Photosynthesis
 Light Reactions- solar energy is captured (by
chlorophyll in the thylakoids) and converted
into chemical energy (ATP and NADPH).
 Photophosphorylation- creates ATP through
the use of the ETC in the light reactions.
 Dark Reactions/Calvin Cycle- chemical
energy is used to make organic compounds
of food. (ie: glucose) Occurs in stroma.
 Carbon Fixation- CO2 (from air) is combined
with molecules present in chloroplast to form
organic molecules that are reduced to
carbohydrates. (w/NADPH)
Warm Up Exercise
Light Energy
 Photons- packets of light
energy.
 Pigments- substances that
absorb visible light.
 Chlorophyll a, chlorophyll b,
carotenoids.
 Spectrophotometer-
instrument that measures the
ability of a pigment to
absorb various wavelengths
of light.
Absorption Spectrum
and Action Spectrum
Photosystems
 Photosystems-
a reaction
center
complex
surrounded by
light harvesting
complexes
(pigment
molecules +
proteins).
 PS II (P680)
and PS I
(P700)
The Light Reactions
 Photon of light is absorbed by pigment
molecule in PS II exciting electrons.
 Electrons are passed along pigment
molecules in the light-harvesting complex, to
the reaction center complex, and ultimately
to the primary electron acceptor.
 Water molecule is split into 2 e-, 2 H+ and O.
These e- are transferred back to P680 and
H+ is released to lumen of thylakoid. O
combines with O from previous water
splitting to release O2.
The Light Reactions
 Electrons are passed from primary electron
acceptor in PS II down the ETC to PS I. As
electrons pass through the ETC, ATP is
generated.
 Meanwhile, PS I has absorbed light, excited
electrons, that are assed on to P700 and to
primary electron acceptor, leaving p700
without electrons.
 P700 accepts electrons from ETC (that came
from PS II).
The Light Reactions
 Excited electrons are passed from primary
electron acceptor of PS I through a second
ETC.
 Electrons move through a protein called
ferredoxin and to NADP+ reductase, where
they are accepted by NADPH. This stores
the energy of the electrons into a form that
can be transferred to the Calvin Cycle.
(No chemiosmosis, thus no ATP in this ETC)
The Light Reactions
 j
Warm Up Exercise
 What are the main pigments in chloroplasts?
Cyclic Electron Flow
 Cyclic Electron Flow- electrons take an
alternative pathway that uses PS I but not PS II.
Differences in ETC
 Type of
phosphorylation
 Where electrons
come from
 Where energy
comes from
 Direction/locatio
n of H+ pumping
Light Reactions
 kjh
Calvin Cycle
 CO2 enters the Calvin Cycle from the light
reactions and exits as sugar.
 The carbohydrate produced in the Calvin
Cycle is not actually glucose, but a 3-carbon
sugar called G3P.
 To synthesize 1 molecule of G3P, the process
has to happen 3x fixing 3 molecules of CO2.
 Expends 9 ATP and 6 NADH.
Calvin Cycle
 1: Carbon Fixation- CO2 is attached to 5-C
molecule (ribulose bisphosphate- RuBP) to form a
6-C molecule. Enzyme: Rubisco.
 2: Reduction- molecule from phase 1 is reduced
(by NADPH) to become 6 molecules of
glyceraldehyde 3-phosphate (G3P). One G3P is
released.
 3: Regeneration of CO2 Acceptor (RuBP)- other 5
molecules of G3P are rearranged to create 3
more CO2 acceptors (RuBP)