Chapter 3,17 Flashcards
(52 cards)
How does each amino acid differ from one another?
from the molecular structure of their R-group
why is the α carbon in glycine not asymmetrical?
glycine only has 3 unique groups
how does cysteine differ from other amino acids?
has a sulfhydryl functional group, can form disulphide bonds
what kind of turn can a protein with glycine make?
tight turns b/c of how small glycine is
what is special about proline’s shape?
R-group connects to amino group in backbone
what does proline do in proteins?
affects flexibility, found in permanently locked turns
what kind of bonds are between double bonded carbon and peptide bonds in polypeptides?
a partial double bond
why can’t peptide bonds rotate?
peptide bonds have 2nd resonance form, C=O and N-H reside in a single plane
what is the difference between proteins and polypeptides?
proteins - correctly folded
polypeptides - not correctly folded
what bonds are present in primary structures?
peptide bonds
what bonds are present in secondary structures?
hydrogen bonds between peptide backbones, which determine polypeptide orientation (a helices or b pleated sheets)
what bonds are present in tertiary structures?
ionic, hydrogen, and covalent bonds (such as disulfide bonds) between R-groups, as well as hydrophobic forces in nonpolar interior
what bonds are present in quaternary structures?
weak bonds
is a polypeptide’s primary structure disrupted when denatured?
No, peptide bonds are polar covalent, hard to break
how is a polypeptide’s primary structure read?
from amino end to carboxyl end
what is an α helix?
tightly twisted coil, stabilized by hydrogen bonds btwn an amino acid’s carbonyl group and an amino acid’s amino group 4 residues away
what is a β sheet?
pleated sheet stabilized by hydrogen bonds between carbonyl groups in one chain and amino groups in other chain
what is a tertiary structure?
protein’s 3D shape, made of several secondary structures, formed from weak bonds and interactions btwn R-groups
how is the ball-and-stick model useful for illustrating tertiary structures?
shows atoms and bonds
how is the ribbon model useful for illustrating tertiary structures?
shows a helices and b sheets of secondary structures in proteins
how is the space-filling model useful for illustrating tertiary structures?
shows actual size, shape, and contour of protein
the tertiary structure determines a protein’s function by:
contours and distribution of charge on outside
presence of cavities
what are functions of proteins?
enzymes, defense, storage, transport, hormonal, structural, contractile and motor, receptor and communication
what factors causes a protein to denature?
pH, temp, salt conc.
