Unit B11: Cell Biology Unit B11: Cell Biology (Enzymes)(Enzymes)Authored by Michelle ChomaAuthored by Michelle Choma©©

Students who have fully met the prescribed learning outcomes Students who have fully met the prescribed learning outcomes (PLO’s) are able to:(PLO’s) are able to:

Analyze the roles of enzymes in Analyze the roles of enzymes in biochemical reactions.biochemical reactions.

• explain the following terms: explain the following terms: metabolism, enzyme, substrate, metabolism, enzyme, substrate, coenzyme, activation energy.coenzyme, activation energy.

• use graphs to identify the role of use graphs to identify the role of enzymes in lowering the activation enzymes in lowering the activation energy of a biochemical reactionenergy of a biochemical reaction

PLO’s continuedPLO’s continued

explain models of enzymatic action explain models of enzymatic action (e.g., induced fit).(e.g., induced fit).

differentiate between the roles of differentiate between the roles of enzymes and co-enzymes in biochemical enzymes and co-enzymes in biochemical reactions.reactions.

identify the role of vitamins as identify the role of vitamins as coenzymes.coenzymes.

PLO’s continuedPLO’s continued apply knowledge of proteins to explain apply knowledge of proteins to explain

the effects on enzyme activity of pH, the effects on enzyme activity of pH, temperature, substrate concentration, temperature, substrate concentration, enzyme concentration, competitive enzyme concentration, competitive inhibitors, and non-competitive inhibitors, and non-competitive inhibitors including heavy metals.inhibitors including heavy metals.

devise an experiment using the devise an experiment using the scientific method (e.g., to investigate scientific method (e.g., to investigate the activity of enzymes). Liver catalase the activity of enzymes). Liver catalase experiment!experiment!

And lastly!!And lastly!!

identify the thyroid the source gland identify the thyroid the source gland for thyroxin and relate the function of for thyroxin and relate the function of thyroxin to metabolism thyroxin to metabolism

Terms to KnowTerms to Know

Metabolism:Metabolism: Describes the constantly occurring Describes the constantly occurring

chemical reactions in a cell necessary for chemical reactions in a cell necessary for life. life. E.g., the chemical reactions involved in the E.g., the chemical reactions involved in the

processes of cellular respiration, DNA processes of cellular respiration, DNA replication, protein synthesis, dehydration replication, protein synthesis, dehydration synthesis and hydrolysis, chemical digestion, synthesis and hydrolysis, chemical digestion, intracellular digestion, Ointracellular digestion, O22/CO/CO22 transport, etc. transport, etc. ALL require molecules called ALL require molecules called enzymesenzymes. .

MetabolismMetabolism

In metabolism some substances are In metabolism some substances are broken down/hydrolyzedbroken down/hydrolyzed to yield to yield energy for vital processes while other energy for vital processes while other substances, necessary for life, are substances, necessary for life, are synthesizedsynthesized---- this require ---- this require enzymesenzymes! !

Enzymes (Enzymes (EE):):

ProteinProtein molecules molecules (recall 3º shape), (recall 3º shape), which which speedspeed up the up the rate of a chemical rate of a chemical reaction without reaction without being used up in being used up in the process (a the process (a catalyst). Enzymes catalyst). Enzymes lowerlower the the Energy Energy of Activationof Activation..

EnzymesEnzymes

Enzymes contain an Enzymes contain an active siteactive site which which interacts with the substrate to produce the interacts with the substrate to produce the end products (see diagram, “induced fit” end products (see diagram, “induced fit” model). model).

With some exceptions, enzymes end in With some exceptions, enzymes end in ““asease”” and are named according to the and are named according to the substrate they interact with, substrate they interact with, e.g. malte.g. maltasease is the enzyme that breaks down is the enzyme that breaks down

the substrate maltose. the substrate maltose.

EnzymesEnzymes

Every reaction requires a Every reaction requires a specificspecific enzyme and undergoes the following enzyme and undergoes the following enzymatic reaction:enzymatic reaction:

EE + + SS ES ComplexES Complex E E + + PPEnzyme + Substrate Enzyme + Substrate Enzyme-Substrate Complex Enzyme-Substrate Complex Enzyme + Enzyme +

ProductProduct

http://www.bbc.co.uk/schools/gcsebitesizhttp://www.bbc.co.uk/schools/gcsebitesize/teachers/biology/activities.shtmle/teachers/biology/activities.shtml

(Animation of enzyme reaction) (Animation of enzyme reaction)

EnzymesEnzymes

Every enzyme typically speeds up Every enzyme typically speeds up only one particular reaction only one particular reaction i.e. very specific to one enzyme i.e. very specific to one enzyme

catalyzing a particular reaction.catalyzing a particular reaction. A hypothetical metabolic pathway is A hypothetical metabolic pathway is

shown below:shown below:

EnzymesEnzymes

Reactions occur in a Reactions occur in a sequencesequence and a and a specific enzymespecific enzyme catalyzescatalyzes eacheach step. step.

Intermediates can be used as Intermediates can be used as starting points for other pathways. starting points for other pathways. E.g. "E.g. "CC" can be used to produce "" can be used to produce "DD" but " but

can also be used to produce "can also be used to produce "FF".".

EnzymesEnzymes

Another look at this…..Another look at this…..

Substrates (Substrates (SS))

The The reactantsreactants in an enzymatic reaction; in an enzymatic reaction; molecules that react with enzymes. molecules that react with enzymes.

MaltMaltasease + H+ H22O + O + MaltoseMaltose Glucose-Glucose-Glucose-MaltGlucose-Maltasease ComplexComplex GlucoseGlucose + + GlucoseGlucose + + MaltMaltasease

EE + H + H22O + O + SS ES ComplexES Complex P P + + EE

Co-enzymesCo-enzymes

Non-proteinNon-protein, organic molecules , organic molecules synthesized from synthesized from vitaminsvitamins that help that help enzymes combine with the substrate.enzymes combine with the substrate. E.g. NAD (nicotidamide adenine E.g. NAD (nicotidamide adenine

dinucleotide) contains niacin, vitamin dinucleotide) contains niacin, vitamin B1; FAD contains vitamin B12.B1; FAD contains vitamin B12.

See B11, role of vitamins for See B11, role of vitamins for specifics.specifics.

Energy of Activation:Energy of Activation:

Reaction proceeds to a product when Reaction proceeds to a product when required energy exists.required energy exists.

For reactions to take place, energy For reactions to take place, energy must be absorbed by the reactants in must be absorbed by the reactants in order to break the bonds. Initial order to break the bonds. Initial investment of energy to start the investment of energy to start the reaction is known as reaction is known as EaEa (energy of (energy of activation)activation)

See following graph of See following graph of Time vs. Time vs. Energy LevelEnergy Level..

Energy of ActivationEnergy of Activation

Heat speeds up the reaction but heat kills Heat speeds up the reaction but heat kills cells, so organisms must use an cells, so organisms must use an alternative, a catalyst, i.e. enzymes.alternative, a catalyst, i.e. enzymes.

Enzymes, which are proteins, speed up a Enzymes, which are proteins, speed up a reaction by reaction by lowering thelowering the EaEa that is that is necessary to start a reaction. necessary to start a reaction.

Compare the ECompare the Eaa of an enzyme catalyzed of an enzyme catalyzed reaction and non-enzyme catalyzed reaction and non-enzyme catalyzed reaction on the previous graph.reaction on the previous graph.

““Induced Fit” Model of Induced Fit” Model of Enzymatic ActionEnzymatic Action

IntroductionIntroduction Enzymes have a 3º structure (recall a Enzymes have a 3º structure (recall a

3-D shape held together by covalent, 3-D shape held together by covalent, ionic, hydrogen and peptide bonds).ionic, hydrogen and peptide bonds).

The portion of the enzyme involved The portion of the enzyme involved in a reaction is the in a reaction is the active siteactive site. .

Every enzyme undergoes the Every enzyme undergoes the following reaction:following reaction:

E + S E + S ES Complex ES Complex E + P E + P

Induced Fit TheoryInduced Fit Theory

Induced Fit theory explains how an Induced Fit theory explains how an enzyme must have the correct shape enzyme must have the correct shape to fit substrate. A change in shape & to fit substrate. A change in shape & temporary bonding occurs between temporary bonding occurs between the E & S. After the reaction takes the E & S. After the reaction takes place, the product no longer fits on place, the product no longer fits on the enzyme, and is freed. The the enzyme, and is freed. The enzyme returns to original shape so enzyme returns to original shape so that it can be used again. that it can be used again.

Steps of the Induced Fit Steps of the Induced Fit TheoryTheory

1.) 1.) Active siteActive site of enzyme has a of enzyme has a unique unique shapeshape and is induced to undergo a and is induced to undergo a slight alteration to fit tighter with the slight alteration to fit tighter with the substratesubstrate and produce an and produce an ES complexES complex

2.) Changed shape of active site 2.) Changed shape of active site disrupts the temporary bonds, disrupts the temporary bonds, promotes the reaction, and the product promotes the reaction, and the product no longer fits and is released.no longer fits and is released.

Steps of the Induced Fit Steps of the Induced Fit TheoryTheory

3.) Active site returns to its original 3.) Active site returns to its original state in order to lower the state in order to lower the energy of energy of activationactivation and is ready to accept and is ready to accept another substrate.another substrate.

Dehydration Synthesis of Dehydration Synthesis of MonomersMonomers

Hydrolysis of a PolymerHydrolysis of a Polymer

Co-enzymes and VitaminsCo-enzymes and Vitamins

Many reactions require a non-protein Many reactions require a non-protein molecule or a metal ion to function molecule or a metal ion to function properly.properly.

Co-enzymes are Co-enzymes are non-proteinnon-protein, organic , organic molecules that molecules that bindbind to enzymes to to enzymes to help enzymes combine with the help enzymes combine with the substrate.substrate.

Co-enzymes/vitaminsCo-enzymes/vitamins

Co-enzymes are synthesized from Co-enzymes are synthesized from vitaminsvitamins. . E.g. Co-enzyme NAD contains niacin, E.g. Co-enzyme NAD contains niacin,

vitamin B1. (NAD+ functions in vitamin B1. (NAD+ functions in cellular respirationcellular respiration by carrying two by carrying two electronselectrons from one reaction site to from one reaction site to another in the cytoplasm and another in the cytoplasm and mitochondria, i.e. NAD+ + 2H ® NADH mitochondria, i.e. NAD+ + 2H ® NADH + H++ H+))

Enzymatic Reaction with a Co-Enzymatic Reaction with a Co-enzyme:enzyme:

Effects on Enzyme ActivityEffects on Enzyme Activity

IntroductionIntroduction Enzyme action occurs when the Enzyme action occurs when the

enzyme and substrate collide. enzyme and substrate collide. During the collision the substrate During the collision the substrate slots into the active site of the slots into the active site of the enzyme.enzyme.

Collisions happen because of the Collisions happen because of the rapid random movement of rapid random movement of molecules in liquids.molecules in liquids.

Factors affecting the rateFactors affecting the rate

The following factors affect the The following factors affect the rate of rate of enzyme activityenzyme activity and therefore the and therefore the amount of products produced: amount of products produced: pHpH temperature temperature [substrate] [substrate] [enzyme] [enzyme] competitive inhibitors competitive inhibitors non-competitive inhibitors, e.g. heavy metals non-competitive inhibitors, e.g. heavy metals

pHpH

Each enzyme has an Each enzyme has an optimum pHoptimum pH that maintains the 3º shape (and its that maintains the 3º shape (and its active site!).active site!).

E.g. StomachE.g. Stomach pH ~ 2 - 3pH ~ 2 - 3

PepsinogenPepsinogen PepsinPepsin

(Inactive)(Inactive) (Active) (Active)

More Examples of pHMore Examples of pH

Small intestinesSmall intestines pH ~ 8.5 – 9pH ~ 8.5 – 9Peptidase, lipase, maltase, trypsin, Peptidase, lipase, maltase, trypsin,

pancreatic amylase pancreatic amylase etc.etc.

BloodBlood pH ~ 7.4 pH ~ 7.4 Carbonic anhydraseCarbonic anhydrase

MouthMouth pH ~ 7pH ~ 7Salivary amylaseSalivary amylase

pHpH

Deviations from optimum pH will Deviations from optimum pH will denaturedenature the enzyme (destroy the the enzyme (destroy the H-bonds, 3º structure and active H-bonds, 3º structure and active site). Loss of 3º structure and ability site). Loss of 3º structure and ability of active site to bond with the of active site to bond with the substrate; enzyme is inactive. substrate; enzyme is inactive. (Note: Denaturation is not usually (Note: Denaturation is not usually

reversible. Some denatured proteins do reversible. Some denatured proteins do renature when their normal pH renature when their normal pH conditions are restored.)conditions are restored.)

Interpreting Interpreting pH vs. Rate of pH vs. Rate of Enzyme ActivityEnzyme Activity graphs graphs::

Interpreting graphInterpreting graph

1.) Enzyme activity increases 1.) Enzyme activity increases with increasing pH until it with increasing pH until it reaches its reaches its optimum pHoptimum pH..

2.) Optimum pH (‘2.) Optimum pH (‘peak peak efficiencyefficiency’) helps to maintain 3º ’) helps to maintain 3º structure, i.e. H-bonds where the structure, i.e. H-bonds where the enzyme is enzyme is most activemost active and and therefore maximum ES therefore maximum ES complexes, P’s and rate of complexes, P’s and rate of enzyme activity. enzyme activity.

Interpreting Interpreting pH vs. Rate of pH vs. Rate of Enzyme ActivityEnzyme Activity graphs graphs::

3.) Further increase of pH 3.) Further increase of pH disrupts the H-bonds, changes disrupts the H-bonds, changes the 3º structure, and the 3º structure, and denaturationdenaturation occurs. Therefore occurs. Therefore fewer active sites are available fewer active sites are available for the reaction and fewer for the reaction and fewer complexes are formedcomplexes are formed

TemperatureTemperature

Each enzyme has an Each enzyme has an optimum optimum temperaturetemperature where maximum activity where maximum activity of ES complexes is achieved. E.g. the of ES complexes is achieved. E.g. the body’s optimum temperature is body’s optimum temperature is 37ºC37ºC. . (Recall from way back: changes in Tº will (Recall from way back: changes in Tº will

cause the speed of molecules/ molecular cause the speed of molecules/ molecular movement to increase/decrease & movement to increase/decrease & therefore molecular collisions)therefore molecular collisions)

TemperatureTemperature

Deviations from optimum Tº will affect Deviations from optimum Tº will affect enzyme activity rate and alter its shape.enzyme activity rate and alter its shape.

Too high of a temperature will cause Too high of a temperature will cause denaturationdenaturation where H-bonds break, lose where H-bonds break, lose it’s 3º structure & changes the shape. The it’s 3º structure & changes the shape. The enzyme no longer has an active site to enzyme no longer has an active site to bond with the substrate & is inactive. bond with the substrate & is inactive. (Note: Denaturation is not usually reversible. (Note: Denaturation is not usually reversible.

Some denatured proteins do renature when Some denatured proteins do renature when their normal temperature conditions are their normal temperature conditions are restored.)restored.)

Interpreting Interpreting Temperature vs. Temperature vs. Rate of EnzymeRate of Enzyme ActivityActivity

graphsgraphs::

37

Temperature Vs. Time for OTemperature Vs. Time for O22 ProductionProduction

About the graphAbout the graph

1.) Enzyme activity increases with 1.) Enzyme activity increases with increasing temperature; increasing temperature; movement/collisions of enzyme and movement/collisions of enzyme and substrate molecules increases and substrate molecules increases and more active sites are more active sites are filledfilled until it until it reaches the reaches the optimum optimum temperaturetemperature..

About the graphAbout the graph

2.)2.) Maximum rate of reaction, Maximum rate of reaction, maximum ES complexes formed at maximum ES complexes formed at optimum temperatureoptimum temperature..

3.) Enzyme activity decreases with 3.) Enzyme activity decreases with increasing temperature as H-bonds increasing temperature as H-bonds break, alters the 3º structure and break, alters the 3º structure and denaturationdenaturation occurs, loss of active occurs, loss of active sites, fewer ES complexes; enzyme is sites, fewer ES complexes; enzyme is inactive.inactive.

[Substrate][Substrate]

Interpreting Interpreting Substrate Substrate Concentration vs. Rate of Concentration vs. Rate of EnzymeEnzyme ActivityActivity graph: graph:

About the About the SubstrateSubstrate graph graph

1.) Enzyme activity increases as 1.) Enzyme activity increases as [substrate][substrate] increases and reaction rate increases to a increases and reaction rate increases to a point.point.

2.) Enzyme activity slows down and levels 2.) Enzyme activity slows down and levels off reaching the off reaching the maximum ratemaximum rate. The . The substrate exceeds the number of enzymes substrate exceeds the number of enzymes and active sites are all and active sites are all occupiedoccupied..

E.g. All maltase activity sites are in E.g. All maltase activity sites are in use.use.

Note:Note: Adding more enzymes (see ‘3’ in graph Adding more enzymes (see ‘3’ in graph above) will further increase the rate of enzyme above) will further increase the rate of enzyme activity as there are more available enzymes and activity as there are more available enzymes and active sites for the substrate.active sites for the substrate.

[Enzyme][Enzyme]

About the About the EnzymeEnzyme graph graph

Reaction rate increases as [enzyme] Reaction rate increases as [enzyme] increases (to the same increasing increases (to the same increasing [substrate]). The same amount of [substrate]). The same amount of products will be produced.products will be produced.

Competitive InhibitorCompetitive Inhibitor

Chemicals that have the same shape as Chemicals that have the same shape as the substrate and will the substrate and will competecompete for the for the active site.active site.

Enzyme cannot react with the “look-a-Enzyme cannot react with the “look-a-like”. This effectively reduces the [of like”. This effectively reduces the [of available enzyme] and inhibits/decreases available enzyme] and inhibits/decreases the reaction.the reaction.

The effect of competitive inhibitors can be The effect of competitive inhibitors can be overcome by increasing the [substrate]. overcome by increasing the [substrate].

Uses---the good, the bad & the Uses---the good, the bad & the ugly!ugly!

Inhibitors are used by many metabolic pathways, Inhibitors are used by many metabolic pathways, for feedback inhibition of products on early stages for feedback inhibition of products on early stages of the pathway to modulate enzyme activity, e.g. of the pathway to modulate enzyme activity, e.g. cellular respiration in the mitochondria cristae cellular respiration in the mitochondria cristae (malonic acid competing for succinic (malonic acid competing for succinic dehydrogenase dehydrogenase

Many medicines are enzyme inhibitors, e.g. sulfa Many medicines are enzyme inhibitors, e.g. sulfa drugs, penicillin to block metabolic pathways of drugs, penicillin to block metabolic pathways of pathogenic bacteria, kidney stone medication, anti-pathogenic bacteria, kidney stone medication, anti-HIV drugs, cancer chemotherapy and even viagra!HIV drugs, cancer chemotherapy and even viagra!

Others can be toxic & poisonous, e.g. deadly nerve Others can be toxic & poisonous, e.g. deadly nerve gas, hydrogen cyanide (competes for cytochrome gas, hydrogen cyanide (competes for cytochrome oxidase), insecticides (parathion, DFP)….oxidase), insecticides (parathion, DFP)….

Competitive InhibitorsCompetitive Inhibitors

EE + + II EIEI ComplexComplex No Reaction or fewer No Reaction or fewer productsproducts

Competitive InhibitorCompetitive Inhibitor-E.g. In the following metabolic pathway:

E1 E2 E3

A B C D competitive inhibitor

If a If a competitive inhibitorcompetitive inhibitor for for enzyme enzyme E2E2 was added to the above was added to the above metabolic pathway, the reaction rate metabolic pathway, the reaction rate would would decreasedecrease & & less of productsless of products C C and D would be producedand D would be produced

Competitive InhibitorCompetitive Inhibitor

Interesting tidbitsInteresting tidbits

Medical info for poisoning:Medical info for poisoning: Ethanol & bad methanol or bad ethanol Ethanol & bad methanol or bad ethanol

glycol (antifreeze)’ E + Bad I glycol (antifreeze)’ E + Bad I EI complex EI complex E + formaldehyde = blindness or oxalic E + formaldehyde = blindness or oxalic crystals in kidneys--ouch! They all crystals in kidneys--ouch! They all compete for alcohol dehydrogencompete for alcohol dehydrogenase. ase. Doctors give ethanol to methanol-poisoned Doctors give ethanol to methanol-poisoned or antifreeze victims---competes for active or antifreeze victims---competes for active site blocking formaldehyde product or site blocking formaldehyde product or kidney tissue damage by oxalic crystals!kidney tissue damage by oxalic crystals!

Non-Competitive Non-Competitive InhibitorInhibitor

Chemicals/inhibitors that bind to an Chemicals/inhibitors that bind to an enzyme at a place other than the enzyme at a place other than the active site, (i.e. ‘no competition at active site, (i.e. ‘no competition at the active site’), which changes the the active site’), which changes the active site so the substrate can’t active site so the substrate can’t bind and bind and slowsslows the reaction rate! the reaction rate!

Less and Less and less productless product produced. produced.

Important Note!!Important Note!!

Because there isn't Because there isn't any competition any competition involved between involved between the inhibitor and the inhibitor and the substrate, the substrate, increasing the increasing the substrate substrate concentration concentration won't help!won't help!

Inhibitor Effects on Rate of Inhibitor Effects on Rate of ReactionReaction

Heavy MetalsHeavy Metals

Heavy metals, e.g. Mercury (Hg), Lead Heavy metals, e.g. Mercury (Hg), Lead (Pb), Silver, Cadmium etc act like an “non- (Pb), Silver, Cadmium etc act like an “non- competitive inhibitor” and cause competitive inhibitor” and cause irreversible reactions.irreversible reactions.

Hg and Pb will cause enzymes to Hg and Pb will cause enzymes to denaturedenature..

DenaturationDenaturation alters the alters the 3º shape3º shape, the , the active siteactive site, the , the formation of ES complexesformation of ES complexes and the and the amount of productsamount of products formed, and formed, and therefore will alter the function of enzyme.therefore will alter the function of enzyme.

The The rate of rxnrate of rxn will will decreasedecrease and and less less productproduct produced. produced.

Interpreting Interpreting Addition of Heavy Addition of Heavy Metals vs. Rate of EnzymeMetals vs. Rate of Enzyme

ActivityActivity graph: graph:

Temp Vs. Heavy MetalTemp Vs. Heavy Metal

The graph above shows the addition The graph above shows the addition of Hg or Pb of Hg or Pb reducesreduces the amount of the amount of product produced over time; the rate product produced over time; the rate slows, lowers, decreases etc. (Note: if slows, lowers, decreases etc. (Note: if the graph becomes less steep, fewer the graph becomes less steep, fewer products are being produced per products are being produced per time unit)time unit)

Enzyme Activity LabsEnzyme Activity Labs

One molecule of catalase can break 40 million molecules of hydrogen peroxide each second. No wonder so many bubbles!!!

ReviewReview

Which line represents an enzyme-catalyzed reaction?

Experimental Design Using Experimental Design Using the Scientific Methodthe Scientific Method

Review the following terms associated Review the following terms associated with Experimental Design: with Experimental Design:

conclusionconclusion dependent variable dependent variable independent variableindependent variable control group control group experimental group procedureexperimental group procedure

control control hypothesis sample hypothesis sample sizesize theorytheory validity validity reliability reliability

Experimental DesignExperimental Design

It is It is importantimportant you preview the you preview the “Experimental Design Question” at:“Experimental Design Question” at:

http://www.bced.gov.bc.ca/exams/http://www.bced.gov.bc.ca/exams/specs/grade12/bi/specs/grade12/bi/07_experimental_design.pdf07_experimental_design.pdf

Steps of the Scientific MethodSteps of the Scientific Method

Observe the natural world and pose a Observe the natural world and pose a clear clear statementstatement of a question. of a question.

Research information related to the question.Research information related to the question. Formulate a Formulate a hypothesishypothesis, i.e. an educated guess or , i.e. an educated guess or

testable answer to the question. (This is done testable answer to the question. (This is done through knowledge, experience, insight through knowledge, experience, insight imagination etc.) imagination etc.)

Design a Design a controlled experimentcontrolled experiment ( (experimental experimental group set-upgroup set-up plus plus control group set-upcontrol group set-up) that is ) that is repeatable in order to test the hypothesis.repeatable in order to test the hypothesis.

Collect, record and analyze data, which will either Collect, record and analyze data, which will either support or reject the hypothesis.support or reject the hypothesis.

Report the results; form a conclusion Report the results; form a conclusion

Effects of Thyroxin on Effects of Thyroxin on MetabolismMetabolism

ThyroxinThyroxin

Thyroxin (Thyroxin (proteinprotein hormonehormone) is ) is produced by the produced by the thyroid glandthyroid gland that that lies at the base of the neck on either lies at the base of the neck on either side of the trachea. side of the trachea.

Plays a role in regulating the body’s Plays a role in regulating the body’s metabolismmetabolism and influences heart and influences heart rate, BP, body To, breathing rate, rate, BP, body To, breathing rate, growth, development etc.growth, development etc.

ThyroxinThyroxin

Thyroid gland accumulates Thyroid gland accumulates iodineiodine by by active transportactive transport in order to produce in order to produce thyroxinthyroxin (Recall B9). It is secreted (Recall B9). It is secreted into the blood stream and affects the into the blood stream and affects the rate of metabolism of the body cells rate of metabolism of the body cells by attaching to by attaching to receptor proteinsreceptor proteins on on the CM.the CM.

ThyroxinThyroxin

ThyroxinThyroxin secretion is regulated by secretion is regulated by the the hypothalamushypothalamus and and anterior anterior pituitarypituitary through a through a negative negative feedback loop/ mechanismfeedback loop/ mechanism.. (Note:(Note: Negative feedback Negative feedback occurs when occurs when

the hormone product of a gland affects the hormone product of a gland affects the hypothalamus or pituitary gland in the hypothalamus or pituitary gland in order to order to inhibitinhibit further release of a further release of a hormone.) See flow diagram…hormone.) See flow diagram…

Feedback loopFeedback loop

ThyroidThyroid

Functions:Functions: Stimulates cells to Stimulates cells to metabolize metabolize

glucoseglucose, therefore more energy is , therefore more energy is produced, and at a faster rate.produced, and at a faster rate.

Increases the Increases the uptake of oxygenuptake of oxygen needed for oxidation of glucose for needed for oxidation of glucose for cell respiration.cell respiration.

Cretinism

WebsitesWebsites http://www.coolschool.ca/content/?http://www.coolschool.ca/content/?

op=simplelor&course=Biology%2012 op=simplelor&course=Biology%2012 (Unit 07) (Unit 07) ☺☺Scroll to Scroll to Lesson 01 – Lesson 05Lesson 01 – Lesson 05 (‘U07L01 – (‘U07L01 –

L05’)L05’) http://highered.mcgraw-hill.com/sites/http://highered.mcgraw-hill.com/sites/

0072421975/student_view0/chapter6/ (Mader’s 0072421975/student_view0/chapter6/ (Mader’s Student Edition Website Support for Chapter 6; Student Edition Website Support for Chapter 6; Essential Study Partner: Cells Unit/Metabolism/ Essential Study Partner: Cells Unit/Metabolism/ Enzymes) or… Enzymes) or… http://www.mhhe.com/biosci/genbio/espv2/data/chttp://www.mhhe.com/biosci/genbio/espv2/data/cells/004/index.html (Metabolism: Energy of ells/004/index.html (Metabolism: Energy of Activation & Enzymes)Activation & Enzymes)

WebsitesWebsites http://www.phschool.com/science/biology_place/http://www.phschool.com/science/biology_place/

index.html (The Biology Place; Go to Lab Bench, index.html (The Biology Place; Go to Lab Bench, click on ‘Lab 2: Enzyme Catalysis’)click on ‘Lab 2: Enzyme Catalysis’)

http://www.ekcsk12.org/science/aplabreview/http://www.ekcsk12.org/science/aplabreview/lab02.htm (Enzyme Catalysis Lab Review)lab02.htm (Enzyme Catalysis Lab Review)

http://www.bbc.co.uk/schools/gcsebitesize/http://www.bbc.co.uk/schools/gcsebitesize/biology/humansasorganisms/biology/humansasorganisms/0nutritiondigestionrev6.shtml (Enzyme0nutritiondigestionrev6.shtml (Enzyme

Review & Test)Review & Test) http://sps.k12.ar.us/massengale/pwpt_biology.htmhttp://sps.k12.ar.us/massengale/pwpt_biology.htm (Terrific power points on (Terrific power points on Scientific MethodScientific Method and and Identifying Controls & VariablesIdentifying Controls & Variables))

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ap1int.htm#biochem ap1int.htm#biochem ☺☺Check out the many topics & related articles. Check out the many topics & related articles. http://faculty.clintoncc.suny.edu/faculty/http://faculty.clintoncc.suny.edu/faculty/

Michael.Gregory/files/Bio%20101/BioMichael.Gregory/files/Bio%20101/Bio%20101%20Lectures/Energy/energy.htm%20101%20Lectures/Energy/energy.htm Enzyme Lecture and an enzyme lab at…Enzyme Lecture and an enzyme lab at…

http://faculty.clintoncc.suny.edu/faculty/http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20101/BioMichael.Gregory/files/Bio%20101/Bio%20101%20Laboratory/Enzymes/Enzymes.htm %20101%20Laboratory/Enzymes/Enzymes.htm

WebsitesWebsites http://www.phschool.com/science/biology_place/http://www.phschool.com/science/biology_place/

labbench/lab2/intro.htmllabbench/lab2/intro.html http://www.bbc.co.uk/education/asguru/biology/http://www.bbc.co.uk/education/asguru/biology/

02biologicalmolecules/01proteins/11enzymes/02biologicalmolecules/01proteins/11enzymes/index.shtmlindex.shtml

http://www.lewport.wnyric.org/jwanamaker/http://www.lewport.wnyric.org/jwanamaker/animations/Enzyme%20activity.html animations/Enzyme%20activity.html

http://www.chemsoc.org/networks/learnnet/cfb/http://www.chemsoc.org/networks/learnnet/cfb/enzymes.htmenzymes.htm

http://glencoe.mcgrawhill.com/sites/http://glencoe.mcgrawhill.com/sites/0078695104/student_view0/0078695104/student_view0/brain_pop_movies.htmlbrain_pop_movies.html (A cutie animated video (A cutie animated video on Scientific Method; practice quiz)on Scientific Method; practice quiz)