Chapter 1, Amino Acids Flashcards
Which amino acids cluster on the surface of membrane proteins?
Nonpolar
Which amino acids cluster on the surface of soluble proteins?
Polar
The sulfhydryl groups (SH) of cysteine molecules can become oxidized to form _________, a dimer of cysteines. This molecule contains a covalent disulfide bond (S-S).
cystine
Which amino acids have hydroxyl groups (OH) which can form hydrogen bonds?
Serine, Threonine, and Tyrosine
Both the carbonyl and the amide group of which two uncharged polar amino acids can also participate in hydrogen bonding?
Asparagine and Glutamine
What type of bonds are formed in an oxidative reaction in which 2 H atoms of the sulfhydryl (thiol) groups are transferred to an acceptor molecule?
Disulfide bonds
Disulfide bonds are considered strong _________ bonds.
covalent
Acidic side chains are ionized or “charged” at pH 7. Aspartic acid and glutamic acid are called __________ and _________ respectively in an ionized state.
aspartate and glutamate
Histones are used to bind DNA. Which two amino acids are found in histones?
Histidine and Lysine
What is the most basic (alkaline) amino acid?
Arginine
Amino acids can be biochemically altered to produce non-amino acids such as dopamine (epinephrine and norepinephrine) and melanin. T3 and T4, which are thyroid hormones associated with metabolic rate can also be produced. All of these are synthesized from what amino acid?
tyrosine
Serotonin, which functions as a neurotransmitter as well as in platelets and also in intestinal mucosa, is synthesized from what amino acid?
*Popularly thought to contribute to feelings of well-being and happiness.
tryptophan
Melatonin (sleep cycle), a pineal gland hormone, is synthesized from what non-amino acid derivative which is derived from tryptophan?
serotonin
Penicillin is bio-synthesized by the condensation of which two amino acids?
cysteine and valine
Histamine, which is a bioactive mediator, is formed from what amino acid?
histidine
Creatine is a high-energy compound that can be used by the muscle when phosphorylated. It is synthesized from what two amino acids among other biochemicals?
glycine and arginine
One widely accepted scale or hydrophobicity (how hydrophobic something is) ranks which amino acids as the most and least hydrophobic?
Most Hydrophobic - isoleucine
Least Hydrophobic - arginine
Because proline has a side chain that forms a 5-member ring whose structure imparts stiffness and can cause bending of the peptide chain, proline is also considered what?
an imino acid
The bond structure between them is the same, but the geometric positioning of the atoms and the functional groups is different.
stereoisomers
What is the only amino acid that is achiral? (Has two H’s)
glycine
Biologically based synthesis produces only one enantiomeric form, the (D or L)-amino acid.
L-amino acid, It’s safe to say that all amino acids are L- except for glycine which is neither.
Which amino acids (D or L) occur in bacterial cell walls and in peptide antibiotics?
D-amino acids
Chemically based in vitro synthesis produces ________ mixtures, which are equal amounts of both the L- and the D- enantiomers.
racemic
Umami is a meaty-like taste, generally associated with the taste of the modified amino acid ________ ________ or _ _ _.
monosodium glutamate or MSG
Volatile sulfur compounds (VSC) are formed by breakdown of sulfur containing peptides and proteins by bacteria inhabiting the oral cavity which leads to halitosis (male oral odor or “bad breath”). The offending amino acids in these peptides and proteins would be those that contain sulphur which are…?
MC – Sulf
methionine and cysteine
Which non-standard amino acid is a form of cysteine and what has it changed?
Selenocysteine
*instead of sulfur, molecule has atom of selenium
Which non-standard amino acid is similar in structure to lysine, but has an added ring? What is the ring? Where is it found?
Pyrrolysine
- has an added pyrroline ring
- found only in Archaea and also a single bacterium
Which two proteinogenic modified amino acids are essential for the stabilization of collagen?
Hydroxyproline (hyp) and Hydroxylysine (hyl)
What proteinogenic modified amino acid is found in blood clotting factors and also in bone? *The carboxylation of this amino acid requires what vitamin?
Gamma-carboxyglutamate (Gla)
*Vitamin K
