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biochem lec > water and buffers > Flashcards

water and buffers Flashcards

1
Q

resists pH change

A

buffers

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2
Q

what is the pH range of blood?

A

7.35-7.45

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3
Q

what is the abundant buffer in human body?

A

bicarbonate (carbonic acid)

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4
Q

this is the most abundant component of every cell

A

water

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5
Q

everything that happens in cells, even reactions buried deep inside enzymes, away from water, is influenced by

A

water’s chemistry

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6
Q

needed in catabolic processes

A

water

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7
Q

this dissolves salts

A

water

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8
Q

electrolyte are dissolved what?

A

dissolved ions

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9
Q

uric acid forms what?

A

oxalates

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10
Q

is a measure of the tendency of an atom to attract a bonding pair of electrons

A

electronegativity

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11
Q

electronegativity follows this trend

A

periodic trend

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12
Q

this is the relative “pull” of nuclei for outer shell electrons

A

electronegativity

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13
Q

these electrons are responsible for bonding

A

valence electrons

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14
Q

nonmetal have what charges?

A

negative charges

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15
Q

what elements have the highest electronegativity?

A

F, O, N, Cl

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16
Q

it is the most commonly used electronegativity values

A

pauling scale

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17
Q

the most electronegative element

A

fluorine (4.0)

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18
Q

the least electronegative elements

A

cesium and francium (0.7)

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19
Q

unlike charges

A

attraction

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20
Q

water is a what molecule?

A

polar molecule

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21
Q

water is a polar molecule because charges are distributed around it _____, not ______

A

unevenly; symmetically

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22
Q

CO2 is a what molecule?

A

nonpolar, but has polar bonds

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23
Q

μ=0

A

molecular dipole of CO2

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24
Q

if same force (both sides) for the pull of nuclei then it is

A

nonpolar

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25
Q

to break the hydrogen bonds (H bonds), what do you need to do?

A

heat

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26
Q

which is greater in size? cation or anion?

A

anion

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27
Q

nadadagdagan ng electron

A

anion (negative)

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28
Q

namimigay ng electron

A

cation (positive)

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29
Q

what is the meaning of this δ-?

A

partial negative

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30
Q

what is the meaning of this δ+?

A

partial positive

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31
Q

the uneven charge distribution in the water molecule makes it ____ and form _____ BONDS

A

dipolar; hydrogen bonds

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32
Q

this dipole is bonding from the atoms

A

bond dipoles

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33
Q

entire molecule bonding

A

molecular dipole

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34
Q

the water molecule has wide ___ shape (the HO-H angle is ____) with ____ sharing of electrons between the oxygen and the hydrogen atoms.

A

V; 104.3°; uneven

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35
Q

____ is described as a SOLVENT because of its ability to dissolve many, but not all, molecules

A

water

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36
Q

they are soluble in water

A

polar molecules and ionic compounds

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37
Q

they are soluble in oils and fats

A

nonpolar molecules

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38
Q

t or f: all nitrates are soluble in water

A

true

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39
Q

any process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions) through gaining or losing electrons

A

ionization

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40
Q

AgNO3 + H2O -> Ag + NO3(aq) + Cl

A

AgCl(s)

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41
Q

alcohol is ____scopic

A

hygroscopic

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42
Q

Oil, which is _____, separates from water when mixed with it. Sodium chloride, which ____, and ethanol, which is ____, can both dissolve in water.

A

nonpolar; ionizes; polar

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43
Q

Ethanol’s solubility in water is crucial for brewers, winemakers, and distillers. If ethanol does not mix with water, there would be no wine, beer or spirits

A

true ka jan

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44
Q

____ solubility uses the like dissolves like rule

A

covalent

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45
Q

substances with the same type of polarity will be ______ in one another

A

soluble

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46
Q

compounds with differing polarities will be ____ in one another

A

insoluble

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47
Q

describes substances that interact well with water and dissolve in it

A

hydrophilic

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48
Q

refers to materials that are non-polar and do not dissolve in water

A

hydrophobic

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49
Q

nonpolar hydrocarbons (hexane); lipids (fats and cholesterol)

A

hydrophobic

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50
Q

ionic compounds, polar organic compounds, weak acids, sugars

A

hydrophilic

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51
Q

refers to compounds that have both (hydrophilic and hydrophobic) properties

A

amphiphilic

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52
Q

____, for example are AMPHIPHILIC, containing a long, ____ and a _____

A

soaps; nonpolar aliphatic tail; head that ionizes

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53
Q

the ______ PORTIONS of the soap ions associate with each other and exclude water

A

nonpolar

54
Q

the result is that the soap ions arrange themselves as _____ with the _____ PORTIONS on the interior of the structure away from water and the ____ PORTIONS on the outside interacting with water

A

micelles; nonpolar; polar

55
Q

other amphiphilic substances

A

membrane lipids

56
Q

types of membrane lipids

A

glycerophospholipids and sphingolipids

57
Q

liposome has how many layers?

A

two layers

58
Q

the interaction of the polar heads with water returns the water to its more disordered state. this increase in disorder, or ______, drives the formation of micelles

A

entropy

59
Q

the same forces drive glycerophospholipids and sphingolipids to spontaneously form ____

A

lipid bilayers

60
Q

_____ portions of the molecules interact with each other to exclude _____

A

nonpolar; water

61
Q

_____ portions arrange themselves on the outsides of the bilayer

A

polar

62
Q

another example is seen in the folding of _____PROTEINS in the cytoplasm

A

globular

63
Q

____ amino acids are found in the _____ portion of the protein (water excluded)

A

nonpolar; interior

64
Q

interaction of the nonpolar amino acids turns out to be a driving force for the folding of proteins as they are being made in an aqueous solution

A

trulalu

65
Q

these tiny charges (δ+ and δ-) result in formation of _____, which occur when the partial positive charge of a hydrogen atom is attracted to the partial negative of another molecule

A

hydrogen bonds

66
Q

in water, that means the _____ of one water molecule is attracted to the _____ of another

A

hydrogen; oxygen

67
Q

since water is an _____ molecule, it means also that the charges are ______

A

asymmetrical; asymmetrical

68
Q

such an uneven distribution is what makes a _____

A

dipole

69
Q

are important for interactions with other dipolar molecules and for dissolving ionic substances

A

dipolar molecules

70
Q

the _____ BONDS in biochemistry are very important and cannot be overemphasized

A

hydrogen

71
Q

proton acceptor

A

base

72
Q

proton donor

A

acid

73
Q

t or f: hydrogen bonds are not exclusive to water

A

true

74
Q

they are important forces holding together macromolecules that include proteins and nucleic acids

A

hydrogen bonds

75
Q

these bonds occur within and between macromolecules

A

hydrogen bonds

76
Q

each hydrogen bond is relatively ____ (compared to a covalent bond) but collectively they can be quite ____

A

weak; strong

77
Q

occurs between bases in opposite strands of DNA is based on hydrogen bonds

A

complementary base pairing

78
Q

also play roles in binding of substrates to enzymes, catalysis, and protein-protein interaction, as well as other kinds of binding, such as protein-DNA, or antibody-antigen

A

hydrogen bonds

79
Q

hydrogen bonds are ____ than _____ bonds and their strength varies from very weak (___ kJ/mol) to fairly strong (___ kJ/mol)

A

weaker; covalent; 1-2; 29

80
Q

the farther apart the hydrogen bond distance is, the ____ the bond is

A

weaker

81
Q

hydrogen bonds only occur over relatively ____ distances (_____ Å)

A

short; 2.2-4.0

82
Q

covalent bonds are ___ to break

A

harder to break

83
Q

their weakness (hydrogen bonds), however, is actually quite beneficial for cells, particularly as regards ____

A

nucleic acids

84
Q

the strands of DNA, for example, must be separated over ____ stretches in the processes of _____ and the _______

A

short; replication; RNA synthesis

85
Q

the _____ represents the amount of heat that must be put into the system to break the bond – the larger the number, the _____ the strength of the bond

A

strength of the bond; greater

86
Q

hydrogen bonds are readily broken using ____

A

heat

87
Q

the _____, for example, requires breaking of H-bonds

A

boiling of water

88
Q

when a biological structure, such as a protein or a DNA molecule, is stabilized by hydrogen bonds, breaking those bonds ______ the structure and can result in ______ of the substance – loss of _____ and ____

A

destabilizes; denaturation; structure and function

89
Q

it is partly for this reason that most proteins and all DNAs lose their _____, or _____, structures when heated to boiling

A

native; folded

90
Q

for DNA molecules, denaturation results in ______ of the strands from each other

A

complete separation

91
Q

for most proteins, denaturation means loss of their _____ and with it, loss of the ____ they performed

A

characteristic three-dimensional structure; function

92
Q

t or f: Though a few proteins can readily reassume their original structure when the solution they are in is cooled, MOST CANT

A

trulalerls

93
Q

This is one of the reasons that we cook our food. Proteins are essential for life, so denaturation of _____ proteins results in death of any microorganisms contaminating the food

A

bacterial

94
Q

water can ionize to a slight
extent (___ M) to form ____ and ____

A

10^-7 M; H+ proton; OH- hydroxide

95
Q

Kw means?

A

equilibirum constant of water

96
Q

what is the autoionization constant for water at 25 degrees C?

A

Kw = [H+][OH-] (molar concentration) = 1.0 x 10^-14

97
Q

the _____ of a solution is measured with pH, which is the ____ log of the ____ concentration.

A

proton concentration; negative; proton

98
Q

formula for proton concentration

A

pH = -log [H+]

99
Q

__________ is measured with the pOH by the parallel equation

A

hydroxide concentration

100
Q

formula for hydroxide concentration

A

pOH = -log [OH-]

101
Q

Chemists use the term “_____” to refer to a substance which has protons that can dissociate when dissolved in water (PROTON ____)

A

acid; donor

102
Q

use the term “____” to refer to a substance that can absorb protons when dissolved in water (PROTON ______)

A

base; acceptor

103
Q

a type of acids that are able to donate only one proton

A

monoprotic acid

104
Q

a type of acids that are able to donate only two protons

A

diprotic acid

105
Q

a type of acids that are able to donate only three protons

A

triprotic acid

106
Q

______ acids dissociate completely when in aqueous solution

A

strong acids

107
Q

____ acids dissociate only slightly in aqueous solution

A

weak acids

108
Q

weak acids are critical for life because their affinity for protons causes them to behave like a ____

A

UPS

109
Q

We can think of weak acids as __________ within certain pH ranges, _________ protons as needed

A

Uninterruptible Proton Suppliers; providing or absorbing

110
Q

weak acids thus help to keep the _____ concentration (and thus the pH) of the solution they are in relatively _________

A

H+; constant

111
Q

pH level of milk

A

6.5

112
Q

can act as a buffer

A

milk

113
Q

an acid and a base which differ only by the presence or absence of a proton are called a ________

A

conjugate acid-base pair

114
Q

more hydrogen then it is a/an

A

acid

115
Q

adding hydroxide ions (by adding a strong base like NaOH) to the solution causes the H+ ions to react with OH- ions to make water. Consequently, the concentration of H+ ions would _____ and the pH would ________

A

go down; go up

116
Q

one way to determine the pH of a buffer is by using the ____________

A

Henderson–Hasselbalch equation

117
Q

Henderson– Hasselbalch equation

A

pH = pKa + log([A-]/[HA])

118
Q

The _____ is the _______ and is used to distinguish strong acids from weak acids. It is a measure of the strength of an acid

A

Ka; acid dissociation constant

119
Q

acid dissociation constant formula

A

Ka = [H+][A-]/[HA]

120
Q

strong acids have exceptionally _____ Ka values

A

high Ka values

121
Q

the Ka value is found by looking at the ___________ for the dissociation of the acid

A

equilibrium constant

122
Q

the higher the Ka, the ____ the acid dissociates

A

more the acid dissociates

123
Q

large values of Ka translate to _____ values of pKa

A

lower (inversely proportional with pKa)

124
Q

as a result, the lower the pKa value is for a given acid, the ______ the weak acid is

A

stronger

125
Q

strong Acids, like HCl, essentially have ____ pKa value.

A

no pKa value

126
Q

low pKa means

A

stronger weak acid

127
Q

high pKa means

A

weaker weak acid

128
Q

aspartic acid has how many regions?

A

three regions

129
Q

aspartic has how many possible charges?

A

four charges (+1, 0, -1, -2)

130
Q

How does one predict the charge for an amino acid at a given pH?

A

1) pH < pKa, proton on
2) pH > pKa, proton off

biochem lec (5 decks)

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