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Biochem 3G03 > Chapter 2 - Aqueous Chemistry > Flashcards

Chapter 2 - Aqueous Chemistry Flashcards

1
Q

how much of the human body is water?

A

about 60%. most of it is intracellular water

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2
Q

is water polar or non-polar?

A

polar

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3
Q

geometry of water

A
  • tetrahedral geometry due to its electronic structure: oxygen positioned in centre while having 2 hydrogens in 2 corners, and the 2 unpaired electrons in the other 2 corners
  • sp3 hybridization
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4
Q

hydrogen bond

A
  • type of electrostatic force
  • neighbouring water molecules tend to orient themselves so that each partially positive hydrogen is aligned with a partially negative oxygen
  • these bonds also exist within a water molecule
  • each water molecule can participate in up to 4 hydrogen bonds with up to 4 other water molecules
  • lifetime of a hydrogen bond is 10^-12 seconds
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5
Q

why is the structure of water continually flickering?

A

this is because the lifetime of a hydrogen bond is very short (10^-12 seconds). this causes hydrogen bonds to flicker as they rotate and bend.

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6
Q

some properties of water

A

polar, highly cohesive, high surface tension

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7
Q

what do strong covalent bonds define?

A

basic molecular constitutions

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8
Q

what do weak non-covalent bonds define?

A

3D structures and molecular interactions

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9
Q

forces from strongest to weakest

A

covalent bond, ionic interaction, hydrogen bond, van Der waal forces

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10
Q

hydrogen donors

A

N-H, O-H, S-H

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11
Q

hydrogen acceptors

A

electronegative N, S, O atoms

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12
Q

electronegativity

A

measure of an atom’s affinity for electrons

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13
Q

in biological conditions, why are weak interactions more desirable/important than strong ones?

A
  • interactions that are too strong become permanent
  • this is not good for biological conditions as our biology is constantly changing
  • weaker bonds are easier to control and change
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14
Q

what are key players in hydrogen bonding in biomolecules?

A

hydroxyl group and amine group

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15
Q

types of electrostatic interactions

A

ionic interaction, hydrogen bonds, van Der Waals interactions, high dielectric constant

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16
Q

types of van Der Waals interactions

A

dipole-dipole, dipole-induced dipole, London dispersion forces (i.e. induced dipole-induced dipole)

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17
Q

the cumulative effect of small forces

A

individual small forces have minimal effect. but all of the small forces together are very important and have a great impact on the body.

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18
Q

dielectric constant

A

a measure of a solvent’s ability to diminish the electrostatic attractions between dissolved ions

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19
Q

what type of biological molecules are readily solubilized/

A

those that bear polar or ionic groups

20
Q

hydrophilic

A

water loving

21
Q

hydrophobic

A

water fearing

22
Q

what does the solvation process depend more on?

A
  • depends more on entropy
  • hydration of a non-polar molecule results in water molecules being unable to participate in hydrogen bonding
  • this decreases their freedom to move, resulting in a loss of entropy
23
Q

hydrophobic effect

A
  • exclusion of non-polar substances from an aqueous solution
  • entropy driven: there are no attractive forces holding the non-polar molecules together, rather they aggregate because they are driven out by the unfavourable entropy of hydrating non-polar molecules individually
24
Q

amphiphilic molecules

A

have both hydrophobic and hydrophilic components

25
Q

micelle

A
  • one tailed lipid
  • solvated surface and hydrophobic core
  • formed by amphiphilic molecules
26
Q

bilayer

A
  • two-tailed lipids

- prevents the diffusion of polar substances

27
Q

vesicle

A

lipid bilayer that closes up in order to eliminate its solvent-exposed edges

28
Q

ionic composition of intracellular fluids

A
  • K+ is present in the highest concentration

- Na+ and Cl- exists in small concentrations

29
Q

ionic composition of extracellular fluids

A
  • Na+ is present in the highest concentration
  • Cl- is present in relatively high concentration
  • K+ exists in small concentrations
30
Q

proton jumping

A

proton associated with one water molecule appears to jump rapidly through a network of hydrogen bonded water molecules

31
Q

Kw

A
  • ionization constant

- ionization constant of water is 10^-14 at 25C

32
Q

K

A
  • dissociation constant
  • specifies strength of an acid
  • in H2O ≤≥ H+ + OH-, K =([H+]*[OH-)]/[H2O]
33
Q

relationship between pH and [H+]

A

pH = -log[H+]

34
Q

relationship between [H+] and [OH-]

A

as one increases in concentration, the other decrease, and vice versa

35
Q

acid

A

substance that can donate a proton

36
Q

base

A

substance that can accept a proton

37
Q

relationship between pKa and Ka

A
  • pKa = -log Ka

- strong acids have Ka&raquo_space; 1 (i.e. they will deprotonate entirely)

38
Q

Henderson-hasselbalch equation

A

pH = pK + log [A-]/[HA]

39
Q

polypro tic acid

A

acid that had more than one acidic hydrogen. these acids will have multiple pKa values

40
Q

effective buffering capacity

A

within 1 pH unit of its pK

41
Q

le châtelier’s principle

A

change in concentration of one reactant will shift concentrations of other reactants in order to maintain equilibrium

42
Q

pH &laquo_space;pK

A

[HA]&raquo_space; [A-]

43
Q

pH&raquo_space; pK

A

[HA] &laquo_space;[A-]

44
Q

biological buffers

A

functional groups of proteins and phosphate groups can do this

45
Q

most important buffering system in the body

A
  • CO2 in the blood plasma
  • overall reaction: CO2 + H2O ≤≥ H+ + HCO3-
  • reason for its effectiveness is that it can not only buffer the excess H+ ions, but it can also eliminate them

Biochem 3G03 (3 decks)

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