Chapter 16 Amino acids, proteins, Flashcards
what is hemoglobin and myoglobin an example of?
proteins that transport oxygen in the blood
what is found in an amino acid?
central atom bonded to an ammonium group(NH3+) and a carboxylate group (COO-)
can amino acids be polar or non polar?
both
when is an amino acid nonpolar?
when the R group is H, alkyl, or aromatic (ex: attached to benzine ring or chain of carboxyl groups)
when is an amino acid polar?
when the R group is an alcohol, a thiol, or an amide (ex: anything with Oxygen or SH or O=C-NH2 at the end)
what is sickle-cell anemia caused by? What does it cause to happen?
an abnormality in one of the subunits (an amino acid) of the hemoglobin protein. This changes the shape of the blood cell to change form like a sickle shape, leaving it unable to adequately transport oxygen
what building blocks are proteins made of?
amino acids
are nonpolar amino acids water soluble? what’s the name for this?
no; hydrophobic
are polar amino acids water soluble? what’s the name for this?
yes; hydrophilic
what makes a polar amino acid neutral, acidic, or basic?
Neutral: contains neutrally charged ions in the R group of the amino acid
Acidic: contains negatively charged oxygen in the R group of the amino acid (a carboxylic acid)
Basic: contains positively charged Nitrogen in the R group of the amino acid (an amine)
are the alpha amino acids chiral or achiral?
all a-amino acids are chiral with exception for glycine
how do you tell if you are looking at the L or D enantiomer of a amino acid?
L: NH3+ appears on the left
D: NH3+ appears on the right
what are essential amino acids?
amino acids that cannot be produced in the body and need to come from our diet
what are examples of foods that contain complete proteins of all the essential amino acids?
meat, milk, eggs and fish
what are examples of foods that contain incomplete proteins of only some of the essential amino acids?
grains, beans, and nuts
amino acids can exist as positive ion or negative ion, how would you know which is it?
positive ion: if a solution is more acidic; lower pH than its pI
negative ion: if a solution is more basic; higher pH than its pI
what is the definition of pI?
Isoelectric point: when an amino acid with positive and negative charges is overall neutral in charge
would this have a pH higher or lower than 6?
lower than 6
what is another name for peptide bonds?
amide bonds
what is a peptide?
linking of two or more amino acids via peptide (amide) bonds
Where does a peptide (amide) bond form?
between one amino acid’s COO- group and another amino acid’s NH3+ group
gets ride of a water molecule (one oxygen from the COO- and two hydrogens from the NH3+)
what is the name of two/three/four amino acids bonded by peptide bonds?
dipeptides
tripeptides
tetrapeptides