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).



Metabolism Catabolism Anabolism

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

amino acids.

Energy required/absorbed.



Metabolism Catabolism Anabolism

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 EnergyType 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 – TΔS

ΔG = 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

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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.


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.

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.

Energy Totals

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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

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

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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

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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)

Metabolism Photosynthesis Cellular Respiration

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