lecture 3 Flashcards
amino acid, protein and enzymes
what way does genetic information flow
from DDNA, to RNA, to protein
what nitrogenous bases do nucleotides include
adenine, guanine, cytosine, thymine
what is a zwitterion
an amino acid at pH 7.4, contains a positive negative charge but has a net charge of 0
what is a zwitterionic structure
two groups that are accepting/donating H+
if H has a lower pKa what does it form
H+ is lost first therefore forms a zwitterion
what is a chiral carbon
a carbon that is bonded to 4 different groups
what steroisomers does a chiral carbon result in
D-amino acids and L-amino acids, they are mirror images of each other (enantiomers)
what are the four amino acid classifications
Aliphatic R groups, aromatic R groups, Polar uncharged R groups and polar charged R groups
list four features of aliphatic R groups
Carbon chains, non-polar (no electronegative atoms), hydrophobic, cluster together inside the protein avoiding aqueous environment (3D structure)
list four features of aromatic R groups
Double bonded carbon rings, Non-polar, Hydrophobic, cluster together inside protein (3D structure)
list four features of Polar, uncharged R groups
contains an electronegative heteroatom (N<O or S), hydrophilic - cluster together on the exterior of a protein , the heteroatoms participate in hydrogen bonding with water, cysteine - forms disulfide bridges with other cysteines
list three features of polar, charged R groups
positive or negative charge, hydrophilic, participate in hydrogen bonding
amino acid activation
energy is required to activate amino acids for binding to tRNA. amino acid and adenosine triphosphate (ATP) bind to enzyme to form the activated amino acid
what is a peptide bond
a bond formed when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing H20
what is an alpha helix
a sequence of amino acids in a protein that makes up DNA. has a tightly coiled polypeptide structure
