Metabolism Photosynthesis Cellular Respiration

MetabolismPhotosynthesis

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 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 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).




sometimes called biosynthetic pathways- Ex: synthesis of a protein from

amino acids. Energy required/absorbed.




Bioenergetics the study of how energy flows through

living systems.


Metabolism and Energy Metabolism

Catabolism Anabolism

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



Energy 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



Energy Kinetic

Heat/Thermal comes from the movement of

atoms or molecules associated with kinetic energy



Energy Kinetic

Heat/Thermal Light Energy

Type of energy that can be harnessed to perform work

Ex. Powering Photosynthesis



Kinetic 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

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.




All original energy comes from light. (photosynthesis-

primary producer- consumer- who 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 – TΔSΔG = ΔGfinal – ΔGinitial

Enthalpy

Gibbs Free EnergyΔG = 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 -ΔG

Non-Spontaneous 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 Enzyme- Enzyme + Substrate +Substrate(s) Complex 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

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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.

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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.

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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 Spectrumand Action Spectrum

Photosystems Photosystem

s- 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/

location 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)

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Metabolism Photosynthesis Cellular Respiration