Energy Is Often Defined As The Ability To Do

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Energy is often defined as the ability to dowork.Pair up and list as many forms of energy asyou ound.Gravitational energy.Kinetic energy (energy of motion).Thermal energy (heat energy).Potential energy.

Potential energy is the energy something has basedon its position in the universe.A stretched elastic band has potential energy.A rock held up in the air has potential energy basedon its position.

Chemical energy is type of potential energy.It is the form energy that powers all of the chemicalreactions life processes that take place inside the cellsof all living organisms.The chemical energy contained in any givenmolecule, is found within the bonds that hold theatoms together.

This chemical energy is found in the foods we eat,and it provides our cells with the energy they need tosurvive.The energy is actually found within a few types ofhigh energy bonds that make up the carbs, lipids,and proteins we eat.The chemical energy stored in the bonds between thecarbon, hydrogen and oxygen atoms of these foodswe eat, provide us the energy we need to carry outall of life’s processes.

Chemical Energy and Food

Endothermic (Endergonic) reactions requireenergy (low energy reactants converted to highenergy products).Two examples include; cooking an egg and theelectrolysis of water.H2OH2 O2If the energy required to break the bonds in thereactants is greater than the energy given off bythe formation of the bonds in the products thenthe reaction is endothermic.

The major biochemicalendothermic reaction that occurswithin plants.Photosynthesis involves the breakdown of water molecules withtheir hydrogen atoms beingtransferred to carbon atoms tomake organic molecules likeglucose.6CO2 6 H2OC6H12O6 6O2

Exothermic (Exergonic) reactions releaseenergy (high energy reactants converted to lowenergy products).Examples include burning anything (wood,paper, a candle, gasoline, hydrogen gas.H2 O2H2OIf the energy given off by the formation of thebonds in the products is greater than theenergy required to break the bonds in thereactants then the reaction is exothermic.

The major biochemical exothermic reaction thatoccurs within our bodies.Energy rich molecules like glucose are broken downinside the mitochondria releasing their energy.The process is called cellular respiration.C6H12O6 6O26CO2 6 H2O

The same equation describes theburning of glucose, and the sameamount of free energy is released.If your task was to explode a stick ofdynamite in this room right nowwithout killing us all how wouldyou do it? Pair up and discuss a plan.The achievement of mitochondria istheir ability to release the energy ofglucose in small, discrete steps so thatsome of the energy can be trapped inATP(adenosine triphosphate).

The unit of measure for energy is a calorie (cal).It is defined as the amount of energy required towarm 1 gram of water 1 degree Celsius. Therefore 1kilocalorie (kcal) is the amount of heat needed towarm 1000 grams or 1 liter of water 1 degree Celsius.However, when dealing with calories found in food,things get a little confusing.On product labels, calories is written with a capital"C" and actually represents one thousand calories or1 kcal.

Therefore if 1cup of cereal issaid to contain150 Calories itactually contains150 000 caloriesor 150 kcal, butbecause societyand the foodindustry usesCalories (withthe capital C) itis reported as150 Cal.

Catalysts are chemicals that control the rate or speedof chemical reactions.The catalysts themselves are not changed in theprocess, they are simple used to help chemicalreactions occur.

Enzymes are special protein catalysts that controlthe rates of reactions that occur in living cells.Usually this means allowing the reactions to occur atlower “safer” temperatures for the cell.There are thousands of different enzyme in thehuman body, each designed to catalyze a particularreaction.

Enzymes Involved in DNA Replication1) DNA Polymerase2) DNA LigaseEnzymes Involved in Protein Synthesis1) RNA PolymeraseEnzymes Involved in Recombinant DNA1) Restriction Enzymes2) DNA LigaseEnzymes Involved in DNA Typing1) Restriction Enzymes

Enzymes can be thought of as either“molecular scissors”, that cut larger moleculesin half, like a restriction enzyme cuts up DNA,or a set of “molecular hands” that hold smallermolecules together at proper angles until theyare glued or bonded to form a larger molecule.

The activation energy is the energy required toinitiate a chemical reaction.Enzymes bind temporarily to one or more of thereactants of the reaction they catalyze.In doing so, they lower the amount of activationenergy needed and thus speed up the reaction.

First an enzyme binds to the reactant(s), called thesubstrate.The active site of the enzyme is the area of theprotein that combines with the substrate.Successful binding of enzyme and substrate requiresthat the two molecules be able to approach eachother closely over a fairly broad surface.Thus the analogy that a substrate molecule binds itsenzyme like a key in a lock.

This requirement for complementarity in theconfiguration of substrate and enzyme explainsthe remarkable specificity of most enzymes.Generally, a given enzyme is able to catalyzeonly a single chemical reaction or, at most, afew reactions involving substrates sharing thesame general structure.Which substrate fitsthe yellow enzyme?

1.2.3.Some enzymes are involved in reactions wherelarger molecules are broken apart.These are often referred to as catabolic reactions.Digestive enzymes like amylase provide anexample.

Other enzymes are involved in reactions where twosmaller molecules are linked together. These areoften referred to as anabolic reactions.DNA Polymerase is an example.In this case, the enzyme holds the nucleotidestogether at the precise angle needed for a bond toform between them. CZD5xsOKres

5 general factors affect the rate of enzymeactivity.1) Temperature2) pH3) Concentration of substrate molecules4) Inhibitors (competitive and non-competitive)5) Feedback loops

Who is this?Why is Goldilocks like anenzyme?Enzymes are likeGoldilocks they prefer it notto hot not to cold .but justright.The activity of enzymes isstrongly affected bytemperature.

1) Temperature If the temperature is above or below the optimalrange for a given enzyme, the enzyme activitydecreases sharply.What is the optimal temperature for the blueenzyme? And the pink one?

The activity of enzymes is also affected by pH.If the pH is above or below the optimal range for a givenenzyme, the enzyme activity decreases sharply.What is the optimal pH for Pepsin?Where in the body do you think pepsin is active?What is the optimal pH for Amylase?

Enzyme activity can also be affected by the concentrationof the substrate molecules. Generally the greater theconcentration of the substrate molecules, the greater thenumber of collisions, the greater the rate of reaction.However, once the concentration of the substratemolecules exceeds the concentration of the enzymemolecules, the rate levels off due to a lack of enzymebinding sites.

Pair up and B.S. why the rate of the reaction levels off in theHigh [S] section (which stands for high concentration ofsubstrate)?

The necessity for a close, if brief, fit betweenenzyme and substrate explains thephenomenon of inhibition.There are two types of inhibitors.a) Competitiveb) Non-competitive

a) Competitive inhibitors have shapes very similar to thatof the substrate. They “compete” with the substrate forthe activation sites of enzymes and thus “get in the way”of the reaction.b) Non-competitive inhibitors have the ability to bind tothe “back end” of the enzyme (called the allosteric site)which changes the shape of the active site of the enzymeso it can no longer bind to the substrate. PILzvT3spCQ

There are 2 types of feedback loops.a) Feedback Inhibitionb) Precursor ActivationMetabolic pathways are a series of chemical reactionsof which work sort of like an assembly line toproduce a certain end product.

If the product of a metabolic pathway begins toaccumulate within the cell, it is wasteful for thecell to continue to make that product.In fact it might even be toxic for the cell toproduce any more of that final end product asthe levels of that end product might be out ofthe tolerable range.Feedback inhibition uses enzymes, and theiramazing ability to change shape, to slow downor stop a metabolic pathway.

It does this by binding to theenzyme’s allosteric site,which in turn alters theenzyme’s activation site,and actually degrades the“fit” of the enzymesubstrate complex.Thus further production ofthe enzyme is halted.

If the initial substrate of a metabolic pathwaybegins to accumulate within the cell, it isusually in the cells best interest to use up thesubstrate and not continue to leave it “layingaround”.In fact it might even be toxic for the cell to havethis excess material present as the levels of thatmaterial might be out of the tolerable range.Precursor activation uses enzymes, and theiramazing ability to change shape, to speed up ametabolic pathway.

It does this by binding tothe enzyme’s allostericsite, which in turn altersthe enzyme’s activationsite, and actuallyimproves the “fit” of theenzyme-substratecomplex.Thus speedingproduction of theenzyme is halted. (seeleft diagram)

In the case of feedback inhibition and precursoractivation, the activity of the enzyme is beingregulated by a molecule which is not itssubstrate.In these cases, the regulator molecule binds tothe enzyme at a different site than the one towhich the substrate binds.When the regulator binds to its site, it alters theshape of the enzyme so that its activity ischanged. This is called an allosteric effect.

a) Feedback Inhibition – slow the pathway down.“Apply the brakes”b) Precursor Activation – speed the pathway up.“Step on the gas”

Which diagram (the left or the right) depictsFeedback Inhibition?Which diagram (the left or the right) depictsPrecursor Activation ?

Energy Storage andTransformation ATP (Adenosine Triphosphate) is a nucleotidethat performs many essential roles in the cell.Besides pairing with thymine in DNA (A pairswith T), adenosine can be modified to play thecrucial role of energy provider for cells. ATP isthe major energy currency of the cell, providingthe energy for most of the energy-consumingactivities of the cell.The ATP molecule is like a “molecularrechargeable battery” that can be charged anddischarged over and over again.

Most anabolic reactions in the cell are powered byATP.a) assembly of amino acids into proteinsb) assembly of nucleotides into DNA and RNAc) synthesis of polysaccharides such as glycogen andstarchd) synthesis of triglyceridesOther cell processes that are powered by ATP include:a) Active transportb) Nerve impulsesc) Maintenance of cell volume by removing excesswaterd) Muscle contractionse) Beating of cilia and flagella

In the cytoplasm duringglycolysisIn mitochondria duringcellular respirationIn chloroplasts duringphotosynthesis

The energy is stored in the bonds that hold thethird phosphate group onto the ATP molecule.

ATP is the high energy form of the molecule.When the third phosphate group of ATP isremoved, energy is released.The exact amount depends on the conditions,but on average 7.3 kcal per mole is released.With the third phosphate removed, we nolonger call the molecule ATP, it is now calledADP or adenosine diphosphate.

The chemical equation that represents this release ofenergy is as follows.ATP H2O ADP P (energy)

ADP is the low energy form of the molecule.It can be charged back up into ATP by having thethird phosphate added back into position.To do this, the same amount of energy must beconsumed. Again, the exact amount depends on theconditions, but on average 7.3 kcal per mole isrequired.With the third phosphate back in position, we nolonger call the molecule ADP, it is now called ATP oradenosine triphosphate.This process of adding a phosphate group to amolecule is called phosphorylation.

The chemical equation that represents thisrelease of energy is as follows.ADP P (energy) ATP H2O

Photosynthesis Sunlight plays a muchlarger role in oursustenance than we mayexpect.All the food we eat andall the fossil fuel we useis a product ofphotosynthesis, which isthe process that convertsenergy in sunlight tochemical forms ofenergy that can be usedby biological systems.

Photosynthesis The word equation is as follows:carbon dioxide water --- glucose oxygenThe balanced chemical equation is as follows:6CO2 6 H2O --- C6H12O6 6O2

Leaves and Leaf Structure Plants are the only photosynthetic organisms to haveleaves (although not all plants have leaves).A leaf may be viewed as a solar collector crammedfull of photosynthetic cells.There are two important types of conductive tissuein plant cells.Xylem – carry water from the roots to the leaves.Phloem – carry glucose from the leaves to the rest ofthe plant.

Xylem and Phloem

The Leaf The raw materials of photosynthesis, water andcarbon dioxide, enter the cells of the leaf, and theproducts of photosynthesis, sugar and oxygen, leavethe leaf.

Stomata The stomata is the opening in the leaf in which thecarbon dioxide enters the leaf and the oxygen exits.The stomata opening is controlled by two beanshaped guard cells.

Light Light travels in waves. Different wavelengths oflight are perceived by us as different colors.White light is separated into the different colors oflight by passing it through a prism or water drops ina rain cloud.

Perceived Color Why is a shirt red?Why is a shirt blue?We perceive objectsto be the color theyare because of thelight they reflect.Why is a shirt black?Why is a shirt white?

Chlorophyll A pigment is any substance that absorbs light.The color of the pigment comes from thewavelengths of light reflected (in other words, thosenot absorbed).Chlorophyll is the green pigment common to allphotosynthetic cells. It absorbs all wavelengths ofvisible light except green, which it reflects to bedetected by our eyes.

Spectrometer A spectrometer is used to measure which wavelengthsof light are absorbed by a given pigment.As we would expect, chlorophyll absorbs most colorsof light except green which it reflects.

The organellesresponsible forphotosynthesis are thechloroplasts. Insidethe chloroplasts arethylakoids, thestructural units ofphotosynthesis.Thylakoids are stackedlike pancakes intostacks known as grana.The space surroundingthe grana is referred toas the stroma.Chloroplasts

Photosynthesis –The Steps Photosynthesises is a two-step process.Step 1The Light Reaction – takes place inside thethylakoids.Step 2The Carbon Fixation Cycle – takes place in thestroma.

Step 1 The Light Reaction This takes place in side the thylakoid.In the Light Dependent Processes light strikeschlorophyll in such a way as to excite electrons to ahigher energy state.In a series of reactions (along the ETS) the energy isconverted into ATP and NADPH.Water is split in the process, releasing oxygen as aby-product of the reaction.The ATP and NADPH provide the energy and someof the matter for the Carbon Fixation Cycle.

Thylakoids Inside a Chloroplast

The Thylakoid and the Light Reaction

Energy from light is absorbed by a chlorophyllcomplex at PSII and an electron is pumped down onesite along the ETS.To replace the missing electron, PSII steals anelectron from water (water is the electron loser)splitting the water into H ions and O.The oxygen pair up forming O2 and are given off aswaste.The H ions (called protons) are left to build upinside the thylakoid and help increase the protongradient across the thylakoid membrane.The electron from the water is passed along the ETSlike a hot potato from one electron acceptor to theother.

Along its travels down the ETS the "excited" electronis used to pump H across the membrane into thethylakoid also helping increase the proton gradient.When the electron reaches PSI it is re-energized byanother unit (photon) of light.This time the excited electron is used to reduceNADP turning it into NADPH (here one might saythe electron hops into the electron taxi cab calledNADPH).The proton gradient gives ATPase the energy toconvert ADP into ATP (this is calledphotophosphoralation - in other words convertingADP into ATP).The end result is NADPH and ATP are produced.

Step 2 Carbon Fixation Cycle In the carbon fixation cycle carbon dioxide from theatmosphere (or water for aquatic organisms) iscaptured and modified by the addition of hydrogento form carbohydrates such as glucose.The incorporation of carbon dioxide into organiccompounds is known as carbon fixation.The energy for the carbon fixation cycle comes fromthe light reaction on the form of ATP and NADPH.

The Stroma Inside a Chloroplast

The Carbon Fixation Cycle

Step 2 Carbon Fixation Cycle The 2 products of the light reaction (ATP andNADPH) are now used to drive the carbonfixation cycle.The ATP releases its energy and the NADPHdrops off the electrons and protons (H ) itpicked up from water in the light reaction.The carbon fixation cycle starts as 3 CO2molecules enter the stroma and are grabbed bythe enzyme RuBisCo and each is added to a 5carbon chain.

Step 2 Carbon Fixation Cycle Through a series of reactions and shuffling ofatoms, 6 molecules of glyceraldehyde 3phosphate (G3P) are produced.One G3P is removed and the other 5 G3P arereshuffled and used to regenerate the cycle.The end result is G3P which is a 3 carbon chainthat can be thought of as a half a sugar.Two turns of the cycle are therefore required toproduce 1 sugar molecule.

Summary of Photosynthesis

Cellular Respiration Cellular respiration is the process of oxidizing foodmolecules, like glucose, to carbon dioxide andwater.The energy released is trapped in the form of ATPfor use by all the energy consuming activities of thecell.The word equation is as follows:Glucose oxygen --- carbon dioxide waterThe balanced chemical equation is as follows:C6H12O6 6O2 ---- 6CO2 6 H2O

Cellular Respiration

Cellular Respiration The process occurs in three stages:Glycolysis – splitting of glucose in half into two ½sugars called pyruvate.The Transition Step – technically known as the“Formation of Acetyl Coenzyme A” is a mini-stepthat occurs between steps 1 and 2. Here pyruvate isconverted into Acetyl CoA.Citric Acid Cycle (Kreb's Cycle) – the furtherbreakdown Acetyl CoA into CO2.Electron Transport System – majority of the ATPproduction - high energy NADH and FADH2 are"cashed in" to ATP.

Cellular Respiration Overview

The Stages of Cellular Respiration

Step 1 Glycolysis

Step 1 Glycolysis Glycolysis occurs in the cytoplasm.Glycolysis is the metabolic process in which a6-carbon glucose is split into two 3-carbonpyruvate molecules.A net of 2 ATP and 2 NADH are produced forevery glucose broken down.Glycolysis is not technically a part of cellularrespiration but we will refer to it as step 1 of 3.

1When oxygen is present (aerobic conditions), mostorganisms will continue on to transition and steps 2and 3.Glycolysis – splitting of glucose in half into two ½sugars called pyruvate.

The Mitochondrion The mitochondrion is the power house of the cell.Steps 2 and 3 of aerobic cellular respiration occur inthe mitochondrion.There are 2 membranes inside the mitochondrion.Between the inner and outer membrane is theintermembrane space.The interior of the mitochondrion is called thematrix.

The Mitochondrion

The Transition Step Technically known as the “Formation of AcetylCoenzyme A”.Just as the pyruvate (a 3-carbon chain) enters themitochondria, each pyruvate is shortened by 1carbon forming two 2-carbon chains.

The Transition Step The carbons that are removed each form a carbondioxide and are released.The remaining two 2-carbon chains called AcetylCoA are ready to enter the mitochondrion for step 2.Two more NADH are produced in the process.

Step 2CitricAcidCycle

Step 2 Citric Acid Cycle One at a time, each of the two Acetyl Co-A (2-Cchains) is attached to a 4-C chain (oxaloacetic acid).The 2-C and 4-C make form a 6-carbon chain calledCitric acid (why it’s AKA as the Citric Acid Cycle).During the rest of the cycle, the atoms are shuffledaround, and the carbons that entered the cycle arereleased as carbon dioxide

Step 3 Electron Transport System

Step 3 Electron Transport System Whereas Citric Acid Cycle occurs in the matrix of themitochondrion, the Electron Transport System (ETS)is embedded in the membranes known as the cristae.In the ETS, the higher energy molecules produced inthe Citric Acid Cycle are cashed in, producing ATP.This is achieved by creating a proton gradient in theintermembrane space.

Step 3 Electron Transport System The NADH and FADH2 act like taxi cabs and droptheir electrons and protons off at the ETS (they areoxidized back into NAD and FAD ).The “dropped off” electrons travel along the ETSpumping “dropped off” protons (H ) into theintermembrane space building the proton pressure(gradient).

Step 3 Electron Transport System Eventually the electrons are picked up at the end ofthe ETS by an oxygen atom and join with 2 H toform water.Finally the proton pressure in the intermembranespace is relieved as the protons are released throughthe ATPsynthase back into the matrix, converting 36ADP into 36 ATP.

Step 3 Electron Transport System The process of generating ATP in this way istechnically referred to as oxidative phosphorylation.

Summary of Cellular Respiration

Summary of Cellular Respiration

Where do the 38 ATP Come From?ProcessGlycolysisNumber & Type ofEnergy RichMolecule1)2)TransitionKreb's Cycle1)1)2)3)Number of ATPProduced

Photosynthesis and Cellular Respiration

Anaerobic Pathways Without oxygen to accept the electrons the ETSbacks up as does the Citric Acid Cycle.Under these anaerobic conditions (the absenceof oxygen) pyruvic acid can be routed by theorganism into one of two pathways:1) lactic acid fermentation2) alcohol fermentation

Lactic acid Fermentation Many organisms will also ferment pyruvic acid intoother chemicals such as lactic acid.Humans ferment lactic acid in muscles where oxygenbecomes depleted, resulting in localized anaerobicconditions.

Alcohol Fermentation Is the formation of alcohol from sugar.Yeast, when under anaerobic conditions, convertglucose to pyruvic acid via the glycolysis pathways,then convert pyruvic acid into ethanol, a C-2compound.

Aerobic vs Anaerobic The ratio of ATP produced anaerobically Vsaerobically is 2:38 or 1:19 (per glucose).Anaerobically only the 2 ATP from glycolysisare gained, the two NADH produced inglycolysis require the ETS to be "cashed in" toATP.Instead, the NADH are oxidised (regenerated)to NAD with the energy being used to breakdown the pyruvate into lactate or ethanol.

Energy is often defined as the ability to do work. Pair up and list as many forms of energy as you can. Electrical. Chemical. Nuclear. Magnetic. Elastic. Sound. Gravitational energy. Kinetic energy (energy of motion). Thermal energy (heat energy). Potential energy. Potential energy

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