COLLEGE PHYSICS

Chapter # Chapter TitlePowerPoint Image Slideshow

BIOLOGY

Chapter 6 METABOLISMPowerPoint Image Slideshow

Figure 8.1Metabolism

Figure 6.2

• Energy from the sun.

• Plants photosynthesis

• Herbivores eat those plants

• Carnivores eat the herbivores

• Decomposers digest plant and animal

matter

• Energy lost as heat

Figure 6.4

• This tree shows the evolution of the various branches of life.

• The vertical dimension is time.

• Early life forms (blue) used anaerobic metabolism

Figure 8.UN01

Enzyme 1 Enzyme 2 Enzyme 3

Reaction 1 Reaction 2 Reaction 3ProductStarting

molecule

A B C D

Metabolism & metabolic pathways

Anabolism

Catabolism

Catabolism• Break down

• Complex simple

• Releases NRG

Anabolism

• Builds up

• Simple Complex

• Requires NRG

Bioenergetics

• Energy transformations

in living organisms

Energy = capacity to cause

change

Energy Forms

Potential Energy

• Stored energy

– Capacity to do work

• Due to:

– Location

– Bond arrangement

Energy Forms

Kinetic Energy

• Energy of motion

• Work energy

• Releases heat

Figure 6.8

• Examples of endergonic processes (ones that require energy) and exergonic processes (ones that release energy).

Figure 8.2A diver has more potentialenergy on the platformthan in the water.

Diving convertspotential energy tokinetic energy.

Climbing up converts the kineticenergy of muscle movementto potential energy.

A diver has less potentialenergy in the waterthan on the platform.

Energy Transformations

Potential Kinetic

Figure 8.3

(a) First law of thermodynamics (b) Second law of thermodynamics

Chemicalenergy

Heat

ThermodynamicsEnergy transformations in matter

Matter system

Universe surroundings

Figure 8.3a (a) First law of thermodynamics

Chemicalenergy

Conservation of energy

Figure 8.3b(b) Second law of thermodynamicsTransformation ineffincient

Heat

Figure 6.11

• Energy transferred from one system to another and transformed from one form to another.

Figure 6.12 – Order & Disorder

• Entropy is a measure of randomness or disorder in a system.

• Gases have higher entropy than liquids, and liquids have higher entropy than solids.

Temperature & Entropy

Temperature

Entr

opy

boiling

meltingsolid

liquid

gas

Gibb’s Free Energy

• (∆G) = change in free energy during a process

• (∆H) = change in enthalpy, or change in total energy

• (∆S) = change in entropy

• (T) = temperature in Kelvin

• Only processes with a negative ∆G are spontaneous

• Spontaneous processes can be harnessed to perform work

∆G = ∆H – T∆S

Figure 8.5

• More free energy (higher G)• Less stable• Greater work capacity

In a spontaneous change• The free energy of the system

decreases (G 0)• The system becomes more

stable• The released free energy can

be harnessed to do work

• Less free energy (lower G)• More stable• Less work capacity

(a) Gravitational motion (b) Diffusion (c) Chemical reaction

Free energy = energy capable of work

• Measure instability

Figure 8.6a

(a) Exergonic reaction: energy released, spontaneous

Reactants

Energy

Products

Progress of the reaction

Amount of energy

released(G 0)

Fre

e e

ne

rgy

Free Energy and Metabolism

Figure 8.6b

(b) Endergonic reaction: energy required, nonspontaneous

Reactants

Energy

Products

Amount of energy

required(G 0)

Progress of the reaction

Fre

e e

ne

rgy

Free Energy and Metabolism

Figure 8.7

(a) An isolated hydroelectric system

(b) An open hydro-electric system

(c) A multistep open hydroelectric system

G 0

G 0

G 0G 0

G 0

G 0

Equilibrium and Metabolism

Figure 8.8

(a) The structure of ATP

Phosphate groups

Adenine

Ribose

Adenosine triphosphate (ATP)

Energy

Inorganicphosphate

Adenosine diphosphate (ADP)

(b) The hydrolysis of ATP

ATP powers cellular work

3 main kinds of cellular work:

Chemical/Transport/Mechanical

Lowers energy state

Figure 8.10Transport protein Solute

ATP

P P i

P iADP

P iADPATPATP

Solute transported

Vesicle Cytoskeletal track

Motor protein Protein andvesicle moved

(b) Mechanical work: ATP binds noncovalently to motorproteins and then is hydrolyzed.

(a) Transport work: ATP phosphorylates transport proteins.

Phosphorylation

Figure 8.11

Energy from

catabolism (exergonic,

energy-releasing

processes)

Energy for cellular

work (endergonic,

energy-consuming

processes)

ATP

ADP P i

H2O

ATP cycle

General Enzyme Characteristics

• Biological catalysts

– Increases chemical reactions

• How enzymes work?

– Lower activation energy

– Decrease amt of energy needed to get reaction going

Figure 8.12

Transition state

Reactants

Products

Progress of the reaction

Fre

e e

ne

rgy EA

G O

A B

C D

A B

C D

A B

C D

Decreasing activation energy

Figure 6.15

Course ofreactionwithoutenzyme

EA

without

enzyme EA withenzymeis lower

Course ofreactionwith enzyme

Reactants

Products

G is unaffectedby enzyme

Progress of the reaction

Fre

e e

ne

rgy

Figure 8.14

Substrate

Active site

Enzyme Enzyme-substratecomplex

(a) (b)

Specificity

resuable

Substrates

Substrates enter active site.

Enzyme-substratecomplex

Substrates are heldin active site by weakinteractions.

12

Enzyme

Activesite

Induced fit

Figure 6.16

Substrates

Substrates enter active site.

Enzyme-substratecomplex

Substrates are heldin active site by weakinteractions.

Active site canlower EA and speedup a reaction.

12

3

Substrates areconverted toproducts.

4

Enzyme

Activesite

Figure 6.16

Substrates

Substrates enter active site.

Enzyme-substratecomplex

Enzyme

Products

Substrates are heldin active site by weakinteractions.

Active site canlower EA and speedup a reaction.

Activesite is

availablefor two new

substratemolecules.

Products arereleased.

Substrates areconverted toproducts.

12

3

45

6

Figure 6.16

Figure 6.16Enzyme + substrate ES complex NZ + product(s)

• Induced fit

Figure 8.16a

Optimal temperature fortypical human enzyme (37°C)

Optimal temperature forenzyme of thermophilic

(heat-tolerant)bacteria (77°C)

Temperature (°C)

(a) Optimal temperature for two enzymes

Ra

te o

f re

ac

tio

n

120100806040200

Environmental Conditions (Temperature)

Factors Affect Enzyme Activity

Figure 8.16b

Rate

of

reac

tio

n

0 1 2 3 4 5 6 7 8 9 10pH

(b) Optimal pH for two enzymes

Optimal pH for pepsin(stomachenzyme)

Optimal pH for trypsin(intestinal

enzyme)

Factors Affect Enzyme Activity

Environmental Conditions (pH)

Factors Affect Enzyme ActivityEnvironmental Conditions (Ionic concentration)

• Temperature

– Cooking?

– Refrigeration?

• pH

• Ionic concentration

How can you use this to preserve

your food items from

microorganism that could spoil

your meal?

Factors Affect Enzyme Activity

Cofactors

– Inorganic

• Zn/Fe/Cu

Coenzymes

– Organic

• Vitamins (B12/B6)

• Binds to active site

– Stabilizes transition

state

Figure 8.17

(a) Normal binding (b) Competitive inhibition (c) Noncompetitiveinhibition

Substrate

Activesite

Enzyme

Competitiveinhibitor

Noncompetitiveinhibitor

Ex. ATP

Factors Affect Enzyme Activity

Ex. Aspirin, penicillin, nerve gases• Sulfonamide para-aminobenzoic aicd (PABA)

• Nucleic acid synthesis

Figure 8.17

(a) Normal binding (b) Competitive inhibition (c) Noncompetitiveinhibition

Substrate

Activesite

Enzyme

Competitiveinhibitor

Noncompetitiveinhibitor

Ex. ATP

Factors Affect Enzyme Activity

Ex. Aspirin, penicillin, nerve gases• Sulfonamide para-aminobenzoic aicd (PABA)

• Nucleic acid synthesis

Figure 8.18Two changed amino acids werefound near the active site.

Active site

Two changed amino acidswere found in the active site.

Two changed amino acidswere found on the surface.

Evolution of Enzymes

Figure 8.19a

Regulatory site (one of four)

(a) Allosteric activators and inhibitors

Allosteric enzymewith four subunits

Active site(one of four)

Active form

Activator

Stabilized active form

Oscillation

Nonfunctionalactive site

Inactive formInhibitor

Stabilized inactive form

Ex. Anti-anxiety drugs (Valium, Xanax, Ativan)

• Increase the activity of gamma aminobutyric acid (GABA)

Ex. Na+ activation of thrombin

Ea. AMP

Figure 8.19a

Regulatory site (one of four)

(a) Allosteric activators and inhibitors

Allosteric enzymewith four subunits

Active site(one of four)

Active form

Activator

Stabilized active form

Oscillation

Nonfunctionalactive site

Inactive formInhibitor

Stabilized inactive form

Ex. Strychnine glycine ® in CNS

Figure 6.17 – Competitive & noncompetitive Inhibition

Figure 6.18 Allosteric Inhibitors

• Competitive and noncompetitive inhibition affect the rate of reaction differently.

Competitive inhibitors affect the initial rate but do not affect the maximal rate, whereas

noncompetitive inhibitors affect the maximal rate.

Figure 6.18 Allosteric Inhibitors

Figure 8.19b

Inactive form

Substrate

Stabilized activeform

(b) Cooperativity: another type of allosteric activation

Hemoglobin

Figure 8.20

Caspase 1 Activesite

Substrate

SH SH

SH

Known active form Active form can

bind substrate

Allosteric

binding siteAllosteric

inhibitorHypothesis: allosteric

inhibitor locks enzyme

in inactive form

Caspase 1

Active form Allosterically

inhibited form

Inhibitor

Inactive form

EXPERIMENT

RESULTS

Known inactive form

Figure 8.20a

Caspase 1 Activesite

Substrate

SH SH

SH

Known active form Active form can

bind substrate

Allosteric

binding siteAllosteric

inhibitorHypothesis: allosteric

inhibitor locks enzyme

in inactive form

EXPERIMENT

Known inactive form

Figure 8.20b

Caspase 1

Active form Allosterically

inhibited form

Inhibitor

Inactive form

RESULTS

Figure 6.21 Feedback Inhibition

• An important regulatory mechanism in cells.

Figure 8.21

Active site

available

Isoleucine

used up by

cell

Feedback

inhibition

Active site of

enzyme 1 is

no longer able

to catalyze the

conversion

of threonine to

intermediate A;

pathway is

switched off. Isoleucine

binds to

allosteric

site.

Initial

substrate

(threonine)

Threonine

in active site

Enzyme 1

(threonine

deaminase)

Intermediate A

Intermediate B

Intermediate C

Intermediate D

Enzyme 2

Enzyme 3

Enzyme 4

Enzyme 5

End product

(isoleucine)

Feedback Inhibition

Figure 8.22

Mitochondria

The matrix containsenzymes in solution that

are involved in one stageof cellular respiration.

Enzymes for anotherstage of cellular

respiration areembedded in theinner membrane.

1 m