lecture 1 & 2: review; AA structure and properties Flashcards
ΔG < 0 :
ΔG > 0 :
ΔG = 0 :
ΔG < 0 : spontaneous fwd rxn [exergonic]
ΔG > 0 : non- spontaneous [endergonic]
ΔG = 0 : system at equilibrium
diffusion is driven by _____
diffusion is driven by enthalpy
what between water molecules contribute to favorable/ unfavorable ΔH?
H-bonding between water molecules contribute to favorable ΔH
hydrophobic effect
tendency of non-polar molecules to self-associate in water
driving force of the hydrophobic effect
increased solvent entropy
fixed charges are present in ___ and ___
fixed charges are present in proteins and membranes
charged groups essential for (3)
- stabilizing protein and membrane structure
- solubilizing proteins in water
- recognition of substrates by enzymes
____ acids completely dissociate in water while ___ acids only partially dissociate
strong acids completely dissociate in water while weak acids only partially dissociate
pH = pKa :
pH»_space; pKa :
pH «_space;pKa :
pH = pKa : [A-] = [HA]
pH»_space; pKa : [A-]»_space; [HA]
pH «_space;pKa : [A-] «_space;[HA]
HH equation relates pH to ____ through the ___ term to its _____ through the ____
HH equation relates pH to the intrinsic strength of the acid through the pKa term to its fractional ionization through the [A-]/[HA] term
when pH is far from pKa, the buffer solution will be ____ and can’t act as a buffer
when pH is far from pKa, the buffer solution will be fully protonated and can’t act as a buffer
zwitterion
both (+) and (-) charges at neutral pH
only (L/ D) stereoisomers of amino acids are found in protiens
only L stereoisomers of amino acids are found in protiens
non-polar [hydrophobic] amino acids (5)
- glycine
- alanine
- valine
- leucine
- isoleucine
amino acids often found in the hydrophobic core of proteins [inside/ not exposed to water] (3)
- leucine
- isoleucine
- valine
amino acids that may be found either inside or outside proteins [more able to tolerate water] (2)
- alanine
- glycine
as side chains of aliphatic amino acids increase, they become more/ less hydrophobic
as the side chains increase they become more hydrophobic
which amino acids can be used to calculate the concentration of protiens? (4)
- aromatic amino acids
- phenylalanine
- tyrosine
- tryptophan
phenylalanine is (highly/ not) hydrophobic
phenylalanine is highly hydrophobic
polar amino acids usually found on proteins surface (3)
- serine
- cysteine
- threonine
non-polar amino acid usually buried in the protein (1)
- methionine
proline (is/is not) hydrophobic and is found ____
proline is hydrophobic but is found near the proteins surface
cysteine undergoes a ___ rxn to form a disulfide bond with another cysteine
cysteine undergoes an oxidation rxn to form a disulfide bond with another cysteine
purpose of the disulfide bonds between cysteines
the disulfide bonds between cysteines stabilize the 3D structure of some proteins