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Biochemistry Basics Flashcards

1
Q

what are the two relevant forms of energy in chemistry?

A

kinetic energy (movement of molecules) and potential energy (energy stored in chemical bonds)

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2
Q

First Law of Thermodynamics/Law of Conservation of Energy

A

The energy of the universe is constant; if the energy of a system decreases, the energy of the system must increase and vice versa

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3
Q

Second Law of Thermodynamics

A

Entropy (disorder) of the universe tends to increase; spontaneous reactions tend to increase the disorder of the universe

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4
Q

entropy

A

S, disorder

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5
Q

enthalpy

A

H, bond energy, delta H=delta E+(P*delta V)

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6
Q

spontaneous

A

delta G is negative, reaction is favourable, occur without a net addition of energy and have energy to spare

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7
Q

non-spontaneous

A

delta G is positive, reaction is unfavourable, requires energy input

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8
Q

exergonic

A

energy exits the system, describes reactions with negative change in free energy

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9
Q

endergonic

A

reaction requires energy input, describes reactions with positive change in free energy

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10
Q

how are endergonic reactions completed in the body?

A

by reaction coupling to exergonic reactions

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11
Q

exothermic

A

reactions with a negative change in enthalpy, releases heat into the surroundings

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12
Q

endothermic

A

reactions with a positive change in enthalpy, requires input of heat from the surroundings

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13
Q

in which direction of free energy does a system always move?

A

towards lowest free energy

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14
Q

what does the value of delta free energy depend on?

A

the concentration of reactants and products

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15
Q

delta G naught=

A

standard free energy with all reactants and products at 1M concentration

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16
Q

delta G naught prime=

A

1M concentration of all solutes except H+ and a pH of 7, standardized for human physiological conditions

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17
Q

what is the formula for delta G naught prime?

A

= -RTlnKeq’

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18
Q

what is the formula for delta G (real life)?

A

=delta G naught prime + RTlnQ

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19
Q

equilibrium

A

the point where the rate of reaction in the forward direction equals the rate of reaction in the reverse direction

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20
Q

if a system in equilibrium is disturbed (ex. by adding excess reactant or product), will the value of K change?

A

no, but the value of Q will change

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21
Q

what are the two factors that determine whether a reaction will occur spontaneously (negative free energy change) in the cell?

A

1) the intrinsic properties of the reactants and products (K)
2) the concentration of reactants and products (RTlnQ)

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22
Q

do all spontaneous reactions occur rapidly?

A

no, spontaneous means a reaction is energetically favourable (thermodynamics) but says nothing about rate of reaction (kinetics)

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23
Q

does free energy change depend on the reaction pathway?

A

no, it is only a measurement of the difference in free energy between reactants and products

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24
Q

chemical kinetics

A

the study of reaction rates

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25
why are some spontaneous (thermodynamically favourable) reactions slow to proceed or do not proceed at all?
because of a large activation energy barrier
26
transition state (TS)
unstable state that all reactions proceed through, takes large amounts of energy to produce
27
activation energy Ea
the energy required to produce the transition state
28
what is the barrier that prevents many reactions from proceeding (even thermodynamically favourable ones)?
activation energy
29
what determines the kinetics of a reaction?
activation energy
30
catalyst
lowers the activation energy of a reaction without changing the free energy change by stabilizing the transition state, it is regenerated with each reaction cycle
31
enzymes
biological catalysts that lower Ea without changing delta G
32
what kind of role do catalysts (enzymes) have?
a kinetic role, NOT a thermodynamic one
33
photosynthesis
the process by which plants store energy from the sun in the bond energy of carbohydrates
34
photoautotrophs
generate energy from light to make their own food ex. plants
35
chemoheterotrophs
use energy of food/chemicals produced by other living things ex. humans
36
oxidation
loss of electrons
37
reduction
gain of electrons
38
what determines whether a molecule is oxidized or reduced?
it depends on the other atoms that they are bound to
39
what is indicative of oxidation reactions?
gain of oxygen atoms, loss of hydrogen atoms, loss of electrons
40
what is indicative of reduction reactions?
loss of oxygen atoms, gain of hydrogen atoms, gain of electrons
41
redox pair
describes the pair resulting from oxidation/reduction; when one atom gets reduced, another one must be oxidized
42
catabolism
the process of breaking down molecules
43
anabolism
the process of building up molecules
44
what is the term to describe the process of extracting energy from glucose to produce CO2 and H2O?
oxidative catabolism
45
are anabolic processes generally reductive or oxidative?
reductive
46
Bronsted-Lowry acid
proton donors
47
Bronsted-Lowry base
proton acceptors
48
Lewis acid
electron-pair acceptors
49
Lewis base
electron-pair base
50
what is the relationship between acid-ionization constant Ka and acidity?
the larger the Ka, the stronger the acid; the smaller the Ka, the weaker the acid
51
what is the relationship between base-ionization constant Kb and basicity?
the larger the Kb, the stronger the base; the smaller the Kb, the weaker the base
52
polyprotic
molecules with more than one proton to donate
53
amphoteric
substances that can act as either an acid or a base
54
evertime a polyprotic acid donates a proton, what is the effect on acidity of the resulting species?
the resulting species will be a weaker acid than its predecessor
55
low pH means:
higher [H+] and the solution is acidic
56
high pH means:
lower [H+] and the solution is basic
57
what is the relationship between pKa and acidity?
lower pKa = stronger acid
58
what is the relationship between pKb and basicity
lower pKb=stronger base
59
buffer
a solution that resists changing pH when a small amount of acid or base is added
60
what does a buffer consist of?
presence of a weak acid and its conjugate base (or weak base and its conjugate acid) in roughly equal concentrations
61
what is the most important buffer system in our blood plasma?
the bicarbonate buffer system: H2CO3--->H+ + HCO3-

MCAT-BIOCHEMISTRY (3 decks)

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