amino acids info Flashcards
what is the glue that holds amino acids together
alpha carbon
alpha carbon is bonded to four groups…
amino group (-NH2), carboxyl group (-cooh), a hydrogen atom, and a unique side chan (-r)
all amino acids are chiral except for
glycine
human body only uses what kind of amino acids (L or D)
L-amino acids
L-amino acids
point to the lect in a fischer projection
the amino group is a base that is
typically protonated in the environment of the cell (NH^+)
the carboxylic acid functional group is typically
deprotonated in the aqueous environment of the cell, giving it a negative charge (COO-)
ions whose charges cancel out, producing a molecule with net neutral charge
zwitterions
amino acids whose R-groups contain non-aromatic hydrocarbon chains
non-polar alipathic
amino acids whose R-groups contain aromatic rings, except for histidine
non-polar aromatic
amino acids that can be either charged or uncharged
polar amino acids
amino acids with acidic residues (aspartic and glutamic acid) have an additional BLANK charge (aside from the one at their C-terminus) at physiological ph
negative
amino acids with basic residues (lysine and arginine) have an additional BLANK charge (aside from the one at their N-terminus) at physiological ph
positive
what amino acid is neutral at physiological ph
histidine
if glycine or proline are added into a protein, they will often
destabilize (break down) local alpha-helical secondary structure
what amino acids are targets of phosphorylation
serine, threonine, and tyrosine
addition of a negatively charged phosphate to a molecule, which often changes the structure or function of that molecule
phosphorylation
what amino acids can mimic the presence of a phosphate group
aspartic acid and glutamic acid
cysteine is sometimes able to produce covalent BLANK bonds with other cysteine residues, holding together the subunits of a polypeptide
disulfide
basic and acidic residues can interact to form BLANK due to other attractive positive and negative charges
salt bridges
a covalent BLANK bond can form between the sulfur-containing R groups of two cysteine molecules
disulfide bond
disulfide bonds form between cysteine residues under BLANK conditions
oxidizing (high ph)
disulfide bonds can be broken under BLANK conditions
reducing (low ph)
a molecule composed of two or more amino acids
peptide
the bond connecting together the two amino acids
peptide bond
when an amino group of one amino acid nucleophilically attacks the carboxyl group carbon of another amino acid. linking the two molecules together and releasing a water molecule, what happens
a peptide bond forms
when a peptide bond is formed, the amino and carboxyl group have been transformed into an
amide
peptide bond formation(condensation) is endergonic or exergonic?
endergonic (needs energy)
peptide bond can only be broken by BLANK
hydrolysis
peptide bonds are cleaved with the addition of a water molecule
hydrolysis
peptide bond breaking (hydrolysis) is endergonic or exergonic
exergonic (releases energy)
