water and buffers Flashcards
resists pH change
buffers
what is the pH range of blood?
7.35-7.45
what is the abundant buffer in human body?
bicarbonate (carbonic acid)
this is the most abundant component of every cell
water
everything that happens in cells, even reactions buried deep inside enzymes, away from water, is influenced by
water’s chemistry
needed in catabolic processes
water
this dissolves salts
water
electrolyte are dissolved what?
dissolved ions
uric acid forms what?
oxalates
is a measure of the tendency of an atom to attract a bonding pair of electrons
electronegativity
electronegativity follows this trend
periodic trend
this is the relative “pull” of nuclei for outer shell electrons
electronegativity
these electrons are responsible for bonding
valence electrons
nonmetal have what charges?
negative charges
what elements have the highest electronegativity?
F, O, N, Cl
it is the most commonly used electronegativity values
pauling scale
the most electronegative element
fluorine (4.0)
the least electronegative elements
cesium and francium (0.7)
unlike charges
attraction
water is a what molecule?
polar molecule
water is a polar molecule because charges are distributed around it _____, not ______
unevenly; symmetically
CO2 is a what molecule?
nonpolar, but has polar bonds
μ=0
molecular dipole of CO2
if same force (both sides) for the pull of nuclei then it is
nonpolar
to break the hydrogen bonds (H bonds), what do you need to do?
heat
which is greater in size? cation or anion?
anion
nadadagdagan ng electron
anion (negative)
namimigay ng electron
cation (positive)
what is the meaning of this δ-?
partial negative
what is the meaning of this δ+?
partial positive
the uneven charge distribution in the water molecule makes it ____ and form _____ BONDS
dipolar; hydrogen bonds
this dipole is bonding from the atoms
bond dipoles
entire molecule bonding
molecular dipole
the water molecule has wide ___ shape (the HO-H angle is ____) with ____ sharing of electrons between the oxygen and the hydrogen atoms.
V; 104.3°; uneven
____ is described as a SOLVENT because of its ability to dissolve many, but not all, molecules
water
they are soluble in water
polar molecules and ionic compounds
they are soluble in oils and fats
nonpolar molecules
t or f: all nitrates are soluble in water
true
any process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions) through gaining or losing electrons
ionization
AgNO3 + H2O -> Ag + NO3(aq) + Cl
AgCl(s)
alcohol is ____scopic
hygroscopic
Oil, which is _____, separates from water when mixed with it. Sodium chloride, which ____, and ethanol, which is ____, can both dissolve in water.
nonpolar; ionizes; polar
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
true ka jan
____ solubility uses the like dissolves like rule
covalent
substances with the same type of polarity will be ______ in one another
soluble
compounds with differing polarities will be ____ in one another
insoluble
describes substances that interact well with water and dissolve in it
hydrophilic
refers to materials that are non-polar and do not dissolve in water
hydrophobic
nonpolar hydrocarbons (hexane); lipids (fats and cholesterol)
hydrophobic
ionic compounds, polar organic compounds, weak acids, sugars
hydrophilic
refers to compounds that have both (hydrophilic and hydrophobic) properties
amphiphilic
____, for example are AMPHIPHILIC, containing a long, ____ and a _____
soaps; nonpolar aliphatic tail; head that ionizes
the ______ PORTIONS of the soap ions associate with each other and exclude water
nonpolar
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
micelles; nonpolar; polar
other amphiphilic substances
membrane lipids
types of membrane lipids
glycerophospholipids and sphingolipids
liposome has how many layers?
two layers
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
entropy
the same forces drive glycerophospholipids and sphingolipids to spontaneously form ____
lipid bilayers
_____ portions of the molecules interact with each other to exclude _____
nonpolar; water
_____ portions arrange themselves on the outsides of the bilayer
polar
another example is seen in the folding of _____PROTEINS in the cytoplasm
globular
____ amino acids are found in the _____ portion of the protein (water excluded)
nonpolar; interior
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
trulalu
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
hydrogen bonds
in water, that means the _____ of one water molecule is attracted to the _____ of another
hydrogen; oxygen
since water is an _____ molecule, it means also that the charges are ______
asymmetrical; asymmetrical
such an uneven distribution is what makes a _____
dipole
are important for interactions with other dipolar molecules and for dissolving ionic substances
dipolar molecules
the _____ BONDS in biochemistry are very important and cannot be overemphasized
hydrogen
proton acceptor
base
proton donor
acid
t or f: hydrogen bonds are not exclusive to water
true
they are important forces holding together macromolecules that include proteins and nucleic acids
hydrogen bonds
these bonds occur within and between macromolecules
hydrogen bonds
each hydrogen bond is relatively ____ (compared to a covalent bond) but collectively they can be quite ____
weak; strong
occurs between bases in opposite strands of DNA is based on hydrogen bonds
complementary base pairing
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
hydrogen bonds
hydrogen bonds are ____ than _____ bonds and their strength varies from very weak (___ kJ/mol) to fairly strong (___ kJ/mol)
weaker; covalent; 1-2; 29
the farther apart the hydrogen bond distance is, the ____ the bond is
weaker
hydrogen bonds only occur over relatively ____ distances (_____ Å)
short; 2.2-4.0
covalent bonds are ___ to break
harder to break
their weakness (hydrogen bonds), however, is actually quite beneficial for cells, particularly as regards ____
nucleic acids
the strands of DNA, for example, must be separated over ____ stretches in the processes of _____ and the _______
short; replication; RNA synthesis
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
strength of the bond; greater
hydrogen bonds are readily broken using ____
heat
the _____, for example, requires breaking of H-bonds
boiling of water
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 ____
destabilizes; denaturation; structure and function
it is partly for this reason that most proteins and all DNAs lose their _____, or _____, structures when heated to boiling
native; folded
for DNA molecules, denaturation results in ______ of the strands from each other
complete separation
for most proteins, denaturation means loss of their _____ and with it, loss of the ____ they performed
characteristic three-dimensional structure; function
t or f: Though a few proteins can readily reassume their original structure when the solution they are in is cooled, MOST CANT
trulalerls
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
bacterial
water can ionize to a slight
extent (___ M) to form ____ and ____
10^-7 M; H+ proton; OH- hydroxide
Kw means?
equilibirum constant of water
what is the autoionization constant for water at 25 degrees C?
Kw = [H+][OH-] (molar concentration) = 1.0 x 10^-14
the _____ of a solution is measured with pH, which is the ____ log of the ____ concentration.
proton concentration; negative; proton
formula for proton concentration
pH = -log [H+]
__________ is measured with the pOH by the parallel equation
hydroxide concentration
formula for hydroxide concentration
pOH = -log [OH-]
Chemists use the term “_____” to refer to a substance which has protons that can dissociate when dissolved in water (PROTON ____)
acid; donor
use the term “____” to refer to a substance that can absorb protons when dissolved in water (PROTON ______)
base; acceptor
a type of acids that are able to donate only one proton
monoprotic acid
a type of acids that are able to donate only two protons
diprotic acid
a type of acids that are able to donate only three protons
triprotic acid
______ acids dissociate completely when in aqueous solution
strong acids
____ acids dissociate only slightly in aqueous solution
weak acids
weak acids are critical for life because their affinity for protons causes them to behave like a ____
UPS
We can think of weak acids as __________ within certain pH ranges, _________ protons as needed
Uninterruptible Proton Suppliers; providing or absorbing
weak acids thus help to keep the _____ concentration (and thus the pH) of the solution they are in relatively _________
H+; constant
pH level of milk
6.5
can act as a buffer
milk
an acid and a base which differ only by the presence or absence of a proton are called a ________
conjugate acid-base pair
more hydrogen then it is a/an
acid
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 ________
go down; go up
one way to determine the pH of a buffer is by using the ____________
Henderson–Hasselbalch equation
Henderson– Hasselbalch equation
pH = pKa + log([A-]/[HA])
The _____ is the _______ and is used to distinguish strong acids from weak acids. It is a measure of the strength of an acid
Ka; acid dissociation constant
acid dissociation constant formula
Ka = [H+][A-]/[HA]
strong acids have exceptionally _____ Ka values
high Ka values
the Ka value is found by looking at the ___________ for the dissociation of the acid
equilibrium constant
the higher the Ka, the ____ the acid dissociates
more the acid dissociates
large values of Ka translate to _____ values of pKa
lower (inversely proportional with pKa)
as a result, the lower the pKa value is for a given acid, the ______ the weak acid is
stronger
strong Acids, like HCl, essentially have ____ pKa value.
no pKa value
low pKa means
stronger weak acid
high pKa means
weaker weak acid
aspartic acid has how many regions?
three regions
aspartic has how many possible charges?
four charges (+1, 0, -1, -2)
How does one predict the charge for an amino acid at a given pH?
1) pH < pKa, proton on
2) pH > pKa, proton off
