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BMB461: CH 2
Aqueous solutions, pH, & Buffers
9
Biochemistry
Undergraduate 3
09/22/2010

Additional Biochemistry Flashcards

 


 

Cards

Term
[image]
Definition

polar, covalently bonded atoms

 

weakens electrostatic interactions due to high dielectric constant

 

2 long pairs of e-

 

forms hydrogen bonds (is a H bond donor & acceptor)

 

Term

Hydrogen Bonding

 

direction?

electrostatic : covalent ?

 

Other properties?

Definition

highly directional (linear is strongest)

 

90% electrostatic/10% covalent

 

High melting pt, boiling pt, heat of vaporization

 

Water can form 4 H bonds @ once, bc H bonds are dynamic (constantly breaking & forming)

Term

Hydrophobic Effects

 

Important in Protein folding & lipid-lipid interaction

 

 

 

 

(Polarity)

Definition

Not caused by hydrophobic molecules interacting strongly, but by water interacting strongly!!

 

Water binds strongly to itself, loss of entropy due to ordering.

 

Hydrophobic interactions are a factor in micelle formation

 

Decreases surface area when nonpolar molecules are clumped.

Term

[ concentration ] high or low, inside or outside?

 

Isotonic

 

 

Hypertonic

 

 

Hypotonic

Definition
[image]
Term
p H
Definition

Kw = [H+][OH-] = 1*10^(-14)

Increase in [H] causes decrease in [OH]

 

pH = log (1/[H+]) = -log [H+]

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

 

1 pH unit = 10 times [H+]

 

Term

Strong Acids

 

Strong Bases

Definition

Ionize completely in aqueous solution

 

Mineral acids (HCl, HNO3, H2SO4)

 

Bases (NaOH, KOH)

Term

Weak acids

 

Weak bases

Definition

do not ionize completely

 

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

 

pKa = -log Ka

 

Increasing Ka = Increasing Acid strength = Decreasing Base strength

Term

Polar

 

Nonpolar

 

Amphipathic

Definition

Polar: central atom, surrounding atoms are *the same*, hydrophillic.  SH2, NH3

 

Nonpolar: no central atom, hydrophobic, no charges.  N2, O=O

 

Amphipathic: contains both polar & nonpolar regions

Term
How to chose a Buffer
Definition
the one with the pKa closest to desired pH
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