FINAL - CH2 Flashcards by Taylor Nunes

Bioenergetics is defined as

energy conversion in biological

system

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Bioenergetics is the study of

the various types of energy transformations that occur in living organisms

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3 types of work:

Osmotic: Maintains varying [solute] across biological
membranes

Chemical: Biosynthesis and degradation of organic
molecules

Mechanical: Muscle contraction in animals

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Energy pathway:

Solar energy –> Photosynthesis –> Chemical energy –> Work (3 types)

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Homeostasis

Highly ordered steady state

Requires energy and delays equilibrium

Example: Living organisms

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Equilibrium

Homeostasis is no longer maintained.

Macromolecules tend to equilibrate to their surroundings.

Example: Non-living organisms

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Reduction

Gain of electrons

Increase in the number of hydrogens

Decrease in the number of bonds to oxygen***

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Oxidation

Loss of electrons

Decrease in the number of hydrogens

Increase in the number of oxygens***

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System

Collection of matter in a defined space

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Surroundings

All the space not included in the system

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Thermodynamics is the study of

the changes in energy that accompany events in the universe

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System + Surroundings =

Universe

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Open system

Matter and energy are freely exchanged with the

surroundings

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Closed system

Only energy is exchanged with the surroundings

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Isolated system

Neither matter nor energy is exchanged with the

surroundings

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First law of thermodynamics

Energy can be neither created nor destroyed only transformed from one form to another

ΔE = Efinal – Einitial

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Descriptions of Enthalpy

Exothermic:
Reaction releases heat

Has a –ΔH

Endothermic:
Reaction absorbs heat

Has a +ΔH

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2nd law of thermodynamics

spontaneous processes in the universe tend toward disorder in the absence of energy input

ΔSuniverse = ΔSsystem + ΔSsurroundings > 0

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At equilibrium,

ΔG = 0, the rate of formation of products and reactants is equal

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Gibbs Free Energy

ΔG

Amount of energy capable of doing work

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Exergonic vs. Endergonic Reactions

Exergonic: ΔG < 0, Reaction is overall favorable and spontaneous

Endergonic: ΔG > 0, Reaction is overall unfavorable and non-spontaneous

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Standard Free Energy Change

ΔG°

At standard conditions: 1 atm, 298 K, 1M

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Keq

A + B –> C + D

Keq = [C]eq [D]eq / [A]eq [B]eq

If Keq < 1, favors formation of reactants

If Keq > 1, favors formation of products

If Keq = 1, reaction is at equilibrium

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Biochemical Standard Conditions

ΔG°’

1 atm, 298 K, 1M
pH = 7
[H2O] = 55.5 M
Mg2+ = 1 mM

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A common coupling reaction

ATP hydrolysis

____ is a carrier of chemical energy

ATP

Energy charge

Cells regulate the EC between _____

0.7–0.9

In catabolic pathways Energy charge (EC) is _____

low

In anabolic pathways Energy charge (EC) is _____

high

Water is a ______ and a ______ in | biochemical reactions

solvent | reactant

Water is ___ of the weight of | most organism

70%

Angle in water molecules

104.5°

The typical lifetime of an H-bond is

1 x10^-12 s it is shorter as temperature increases

each water molecule can form ____ hydrogen bonds.

four

__________ occurs between the oxygen atom of one water and the hydrogen of another

electrostatic attraction

H-bonding is especially strong in water because

1. the O—H bond is very polar 2. there are 2 lone pairs on the O atom 3. Each H2O molecule can form four H bonds to other molecules

Important property of H2O

Ice has a lower density than water

Why is ice less dense than liquid water?

each water molecule interacts tetrahedrally with four other water molecules This creates a regular lattice structure, which causes ice to be less dense (expands)

__________ gives water its unusual | properties

Hydrogen bonding

The attraction between the partial electrical charges is | greatest when the three atoms involved lie in _____________

a straight line

Hydrophobic Effect

The tendency of water molecules to minimize their contact with hydrophobic molecules forming "cages"

Dialysis

Diffusion of solutes

Hemodialysis

Acts as an artificial kidney

reversible ionization

H2O --> H3O+ + OH-

Proton jumping:

the proton can rapidly jump from one water molecule to the next

pH + pOH

= 14

Conjugate Base:

base formed by the removal of a proton from an acid

Smaller Pka

Stronger acid

Larger Pka

Weaker acid

Smaller Ka

Weaker acid

Larger Ka

Stronger acid

[H+] [OH-] =

1 x 10^-14 = Kw

Water density

1000 g/L

MW of water

18 g/mol

Buffers

solutions that resist changes in pH upon addition of acid or base

maximum buffering “capacity”

near the pKa of the molecule ± 1 pH

Mass-action ratio

Q Keq = [C]i [D]i / [A]i [B]i

Removing _____ from the blood helps increase the pH

CO2

Removing ______ from the blood helps lower the pH

HCO3-

3 types of membranes

Plasma membrane Endomembranes Mito/Chlor membranes - required for life

Pka =

-log Ka