BIOCHEM: WATER and pH

oxygen is more ____ than hydrogen

electronegative

water molecules form a ____ interaction, which is an asymmetric charge distribution

dipole

water’s strong dipole is responsible for its _______

high dielectric constant

water does not dissolve ______, _______ substances

non-ionic, non-polar

water can decrease the interaction between ions of different charges also called its _______

dielectric property

ions in water are called _____ aka loosened electricity because separating through dissolution frees them to act independently and carry their electrical charge around

electrolytes

who proposed that a solution’s electrical conductivity could be linked to the concentration of ions in the solution

Svante Arrhenius

the higher the electrolytes in a solution, the ____ it’s electrical conductivity (lower, higher)

higher

_____ are important for carrying electrical signals in your body

electrolytes

a ______ electrolyte is one that dissociates or breaks apart completely when dissolved in water and conducts electricity very well (e.g salts, strong acids and bases hydrochloric, sulfuric, and nitric acids; sodium and potassium hydroxide)

strong

_____ electrolytes only dissociate partially in dissolved water, so they’re only somewhat conductive; most of the solute’s molecules stay stuck together, remaining neutral(e.g acetic acid and ammonium hydroxide)

weak

alcohol and sugar are examples of _____ as they dissolve in water but don’t dissociate into ions

nonelectrolytes

Hydrogen peroxide is a ____ molecule, so it dissolves in water but a very ___ electrolyte; when it dissolves it tends to dissociate into a water molecule and a lone oxygen ion

polar, weak

1 mole of a compound = ______

6.022 × 10²3 atoms (16 grams)

molar concentration = _______

molarity

Molarity = ___________

amount of solute in moles divided by volume of solution in liters

Molality =

moles of solute divided by kilogram of solution

_______ Law: the strength of interaction between opoositely charged particles is inversely proportionate to the dielectric constant of the surrounding medium

Coulomb’s Law

water’s ______ and ____ enable water ti dissolve large quantities of charged compounds such as salts

strong dipole and high dielectric constant

water molecules form _________ bonds

weak hydrogen

water’s hydrogen bonds are _____ with a half-life of a few picoseconds

transient

rupture if a hydrogen bond in liquid water requires only about ___ kcal/mol

4.5

water can act as both ____ and ____

hydrogen donor and acceptor

water’s hydrogen bonds influences the physical properties of water and accounts for its ______, ______ and _______

high viscosity, surface tension, and boiling point

Property of water: ________________

Biomedical Significance:

Acts as a thermoregulator in the body,

Capillary action of blood and laminar flow thru vessels,

Provides the elastic property of the lungs,

Maintains cellular shape,

Allows movement of cellular components

high viscosity, surface tension, and boiling point

Property of water: ________________

Biomedical Signifcance:

Diluent for lab reagents without neutralizing the active substance

Allows enzyme-substrate interaction without interfering with the reactions (due to weak bonding forces)

Ionizes “salts” enabling their cellular functions

Dissolve many organic biomolecules

Property of water: __________

Biomedical Significance:

Stabilizes protein structures

Maintains helical structures of DNA

Disassociating property provides a neutral pH

Acts as a buffer system together with other biomolecules

alcohols, carboxylic acids, and amines can serves as both hydrogen acceptors and donors to form hydrogen bonds

water influences structures of _______

biomolecules

____ & ____ bonds stabilize biologic molecules

covalent and non-covalent

____ bonds hold molecules together

covalent

____ bonds stabilize molecular structures (e.g electrostatic forces, can der Waals forces, hydrogen bonding)

non-covalent

Water maintains the 3D structures of ____, ___, and ___

Amino acids and proteins (e.g Henoglobin proteins)

DNA helical structure

Cell membranes (via glycoproteins, phospholipids, and cholesterol)

bonds between the sugars and the phosphate group of the DNA structure are called _____

covalent bonds

____ are chemical species that forms bonds by donating an electron pair

nucleophiles

bonds between the nucleotides in the DNA structure are ______

hydrogen bonds

water is an excellent nucleophile because of its _______

two lone pairs of electrons

Water as a nucleophile cleaves amide, glycoside, or ester bonds that hold biopolymers together aka ______

hydrolysis

water molecules exhibit a slight but important tendency to _________

dissociate

the probability that a hydrigen exists as an ion in pure water is _____

1.8 × 10^9

1 mole of water = ___

18 g

the dissociation constant of water is ___

1.8 × 10^-16 mol/L

solutions are classified as acidic or basic based on their _______ relative to pure water

hydrogen ion concentration

pH is calculated as:

pH = -log[H+]

In the human body, both blood and the cytosol inside the cells have pH values close to _____

neutral

a/an _____ is a substance that increases the concentration of hydrogen ions

acid

a/an ___ raises pH by providing hydroxide

base

the strength of an acid is determined by how readily it disassociates to _______

generate H+

the strength of a base is determined by how readily it disassociates in a solution to ____

accept H+

many biochemicals are weak ____

acids

biological processes require a physiologic pH ____

7.4

biochemicals in cells and in the blood act as ____ to maintain pH

buffers

solutions of weak acids or bases and their conjugates exhibit _____; ability to resist a change in pH following addition of strong acid or base

buffering

a buffer can be created by mixing a ____ with its ____

weak acid, conjugate base

maximum buffering capacity occurs at

pH = pKa

__are proton donors and __are proton acceptors

acids, bases

__completely dissocuate into anions and protons even in strongly acidic solutions (low pH)

Strong acids

___dissociate only partially inacidic solutions

weak acids

___completely dissociated even at high pH

strong bases

HCl and H2SO4 are examples of ____

strong acids

KOH and NaOH are examples of ___

strong bases

the concentration of H+ or pH of a solution is demonstrated by the ____

Henderson-Hasselbalch equation

pH = pKa + log10 (base/acid)

Henderson-Hasselbalch equation

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

Dissociation constant

The rate at which ions separate and come together are equal or equilibrium

Dissociation constant

Strong acids have a kA of ____ (easily donate H+), while weak acids have a Ka of ___ because they do not readily donate H+

>1, <1

__ maintain the pH of a solution despite the addition of a strong acid or base

buffers

---

strongly dissociate (k) and accept H+

Basea

__ strongly disassociate (k) and readily gives off H+

acids

weak acid-conjugate base combinations, resist change most effectively when the desired pH falls within ___ unit or less of their pKa

± 1.0

weak acid-conjugate base combinations are ideal buffers because they typically have ____ concentration of H+ and A-

equal

______ produces CO2, the anhydride of carbonic acid, which if not buffered would produce severe acidosis

Oxidative metabolism

Maintenance of PH involves buffering by ____, ___, and ____ which accept or release protons to resist a change in pH

phosphate, bicarbonate, and proteins

most drugs are either __ or __

weak acids or weak bases

Acidic drugs release a proton causing a ____ to form

charged anion

Weak bases can also release a ___

H+

protonated form of basic drugs is usually ___ and the loss of a proton produces the ____ base

charged, uncharged

A drug passes through membranes more readily if it is __

uncharged

_ , _, _ whose second dissociation falls within the physiologic range are present in proteins and nucleic acids, most coenzymes, and most intermediary metabolites

carboxyl groups, amino groups, and phosphate esters

charge based separations such as __ and __ are also best understood in terms of the dissociation behavior of functional groups

electrophoresis and ion exchange chromatography