Chapter 8: Energy and Metabolism Flashcards by Hannah Tarr

Oxidation and Reduction Reactions

REVIEW DRAWN IMAGE

“OIL-RIG”: “Oxidation is loss” of electrons, “Reduction is gain” of electrons

Reduction is gain, because when atoms gain an electron, the charge is lowered since electrons carry negative charge!

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First Law of Thermodynamics

energy is conserved; cannot be created or destroyed, only transferred and transformed; Chemical reactions involving energy transformations at molecular level; should consider amount of energy static, just changes

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Second Law of Thermodynamics

the total entropy always increases in a system that includes the surroundings as well as the products of the reaction

Chemical reactions results in products with:
 Less ordered energy
 Less usable energy

 Energy has to be put back into this to go from the disordered to ordered state

Example: heat loss(normally not managed)

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Entropy

 Thought of as disorder, energy not available to do work

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Enthalpy

the potential energy of the molecule(heat content) in chemical bonds

Includes potential energy in the bonds of the molecule, plus the effect of the molecule’s kinetic energy(movement) on the pressure and volume of its surroundings

When a reaction releases heat, it is exothermic(products have less potential energy than the reactants)

When heat is taken up, it is endothermic(generating products that have higher potential energy than the reactants)

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Entropy and its relationship to heat loss

when the products of a chemical reaction become less ordered than the reactant molecules = Entropy increases

Every energy transfer increases the entropy of universe due to loss of usable energy (specific system has to be put into place to capture that loss energy efficiently)

Energy transfer has amount of energy lost in the form of unusable heat energy

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Open System

energy can be accessed by consumers; Energy can be transferred between the system and its surroundings(matter and environment involved in energy transfers

In thermodynamics, open systems allow energy to enter and leave

Examples: earth, plants, animals

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Potential energy

energy that is stored in position or configuration

Examples: chemical gradients, energy in chemical bonds

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Potential energy

energy that is stored in position or configuration; stored in chemical bonds

Examples: chemical gradients, energy in chemical bonds

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Kinetic Energy

energy of motion

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Compare Kinetic Energy and Potential Energy

kinetic energy represents energy currently being used while potential energy represents store energy that is not is use, but will be used later

Kinetic energy is objects in motion while potential energy is stationary and has not moved yet

A car driving vs a car stopped at the top of a hill; Clothes stack falling over vs clothing sitting in a dresser; An arrow flying vs a bow pulled back before firing the arrow

when stored energy in chemical bonds are broken, it can be accessed to be used in kinetic energy

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Endergonic reactions

a nonspontaneous reaction that requires energy input to occur

 Photosynthesis, protein synthesis
 Active transport

Energy is supplied from reactant to get product

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Exergonic reaction

spontaneous reaction(does not need outside energy to cause reaction)

Example: Facilitated diffusion, Passive transport, cellular respiration, combustion

Energy is released from reactant to get product

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Compare Endergonic vs Exergonic Reactions

endergonic reactions require input of energy, energy being supplied for product; while exergonic reactions release energy to get product, does not need outside energy

both describe movement of energy

note that a reaction is endergonic in one direction and exergonic in the other

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Gibbs Free Energy

determines whether a reaction is spontaneous or requires added energy to proceed

Based on enthalpy and entropy:

When the change in free energy is negative, it can proceed without energy input, spontaneous(EXERGONIC REACTION! Reaction releases heat/increases entropy)

When the change in free energy is positive, it needs an input of energy to occur(ENDERGONIC REACTION! Absorbing heat/decreases entropy)

STUDY AND DRAW CHARTS TO REMEMBER THIS

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Activation Energy

STUDY/DRAW IMAGE TO HELP

hill you must get over for activation energy to proceed; has reactants state, transition state, and Products state

Transition State: Breaks apart chemical bonds to reorganize them into a product; To proceed a chemical bond has to break and others have to form(Must collide at specific orientation and with certain amount of force to pass through transition stage; note this does not always occur for every reaction out there)

Higher concentration & higher temp = higher reaction rate/ number of collisions

Structure of ATP

DRAWN IMAGE TO HELP
should include phosphate groups, ribose, and Adenine
stores energy in high phosphate bonds; Phosphate groups have negative charges from oxygen, creating a high potential energy that is stored; ATP will break off a phosphate group to release the energy stored from 2 of the phosphate groups; energy made available to cells to perform functions

What do we do when the “hill” becomes too high but we must get over that hill in activation energy process?

Use enzymes! They are catalysts will lower activation energy; they are like shortcuts

having a binding site/active site pocket for reactants to fit into, and the reactants/substrates

Enzymes catalyze RX to occur faster: Bring molecules into closer proximity for it to be more likely a reaction will proceed

Example of an Enzyme

glucokinase, which promotes a transfer between glucose and phosphate by lowering activation energy

Cofactors

organic molecules, like NAD+ and FAD, to make reactions proceed in activation energy

Example: CoA

Competitive Inhibition

Has regulatory molecule that binds to an active enzyme site to prevent enzyme from doing its job; will not break when attached to enzyme

Regulatory molecules are in a competition with substrates that want to bind to perform a chemical reaction; interferes with substrate binding

Reactions proceeding vary from being outcompeted(substrates can outcompete regulatory molecules to bind and produce chemical reaction; regulatory molecules can outcompete substrates to prevent a chemical reaction)

Feedback inhibition

DRAWN IMAGE TO HELP!
DRAWN IMAGE TO HELP!

Enzymes activity inhibited by enzyme’s end product; Turning process on and off beneficia

involves use of reaction product to regulate its own further production

Enzymes activity inhibited by enzyme’s end product; Regulates how much enzyme end product is produced; Turning process on and off beneficial

A substrate attaching to its first enzyme/the first allosteric binding site, can become a molecule that attaches to a second enzyme, and create a second molecule

This process can be repeated until reaching a certain goal/end product that produces a regulatory molecule for the 1st allosteric binding site

Allosteric binding results in feedback inhibition, 1st enzyme cannot bind substrate until the end product regulatory molecule wears out/decreases/ needs more substrated to bind for organism to function

Catabolism

breaking down of macromolecules into their constituent monomers so we can release energy; an exergonic process

Example: food we eat will be broken down into their molecule and into monomers to synthesize our own monomers; create ATP in order to store for later(note some energy is lost)

Anabolism

synonymous with biosynthesis, building up aspect of macromolecules in metabolism

Examples seen in photosynthesis

Induced Fit of an enzyme

Example of glucokinase:  DRAWN IMAGE ATP and glucose bind to the active site of an enzyme and change its shape(an induced fit) Induced fit reorients substrates and bind them closer together at the active site to be closer in activation energy/to lower it

Benefits of a Transition State in Activation Energy

More likely to happen because of induced fit pulls substrates tighter together Transition state NEEDED to break chemical bonds to be individual atoms from covalent atoms(for reaction to proceed (enzymes can possibly lower activation energy to form new substance)

Explain how enzymes lower activation energy

Enzymes bring substrates into closer proximity to be more likely to make it through the transition state of activation energy

Describe how enzymes are optimized for function in specific environments

Enzymes have optimal conditions they can exist in and can vary from organism to organism, Has range that is optimal Environmental effects of enzymes: All have optimal conditions they live in, varies for organisms Temperature effects enzymes: cooler areas put activity at lower range while warmer puts them at increasing rate until reaching the range is properly works at(goes out of range); does not function properly outside of range Humans can be sensitive to quick temp change

Explain how enzymes can be regulated

Competitive inhibition. Noncompetitive (allosteric) inhibition or activation; Explanation of both above and in IMAGES role of phosphorylation?

Role of phosphorylation

addition of phosphate to an organic molecule; carried out by an enzyme Example: addition of phosphate to ADP to create ATP(Enzymes like phosphofructokinase and others add phosphate groups from high energy substrates to ADP, yielding ATP) Example: glucose being introduced to phosphate group, CoA

Metabolic Pathways

series of chemical reactions that takes starting molecule and modifies it(step by step) through multiple intermediates, eventually yielding a product Metabolism composed of synthesis (anabolism) and degradation(catabolism)

Describe 3 ways enzymes can function together

Sequential, Branching, and Feedback Inhibition Note that multiple enzymes needed in metabolic pathways for accurate and efficient conversion of substrates into end products!!!!!!!

Sequential Reactions

In some metabolic pathways, the enzymes work in a linear sequence, with the product of one reaction serving as the substrate for the next reaction. This is a common mechanism in carbohydrate and lipid metabolism.

Branching Pathways

In other metabolic pathways, multiple enzymes can work in parallel pathways that converge to produce the final product. This allows for multiple starting substrates to be converted into the same end product.

Feedback Inhibition

Enzymes in metabolic pathways can also work together through feedback inhibition, a mechanism where the end product of a pathway acts as an inhibitor of an earlier enzyme in the pathway. This ensures that the pathway produces only the required amount of end product and prevents overproduction.

Examples of Metabolism

Example: metabolism of sugar; IMAGE sugars major energy source Example is photosynthesis producing sugars Explain feedback inhibition: Great example of metabolic pathway!!

Compare catabolism and anabolism

IMAGE IN NOTES FOR EXAMPLE! note that “useful forms of energy” is 1st law of thermodynamics and “lost heat” is the second law