Ch. 4 Flashcards
(20 cards)
What is the isoelectric point (pI)?
pH at which the amino acid has no net charge
How does isoelectric focusing work?
Primary structure
Amino acid sequence
Secondary structure
H bonds among backbone atoms
Tertiary structure
All 4 types of interactions between R groups
Quaternary structure
All 4 types of interactions between R groups to join more than
What do beta sheets look like?
When are alpha helices favored?
When are beta sheets favored?
What is a zwitterion?
An electrically neutral but dipolar molecule that contains both positive and negative charges
Practice question: Which type of structure can have all types of interactions and involves multiple polypeptides?
Quaternary
Practice question: For a titration curve of histidine (pKa alpha amino is 9, pKa for alpha carboxyl is 2, and its R group is pKa 6), how many moles of OH would you need to fully deprotonate it?
3
Practice question: Calculate the pI of histidine (pKa alpha amino is 9, pKa for alpha carboxyl is 2, and its R group is pKa 6).
7.5
Practice question: For an amino acid with 2 titratable protons, how many moles of base do you need to obtain a zwitter ion?
1
Practice question: Consider an alpha helix. Which amino acid pair cannot be within 3-4 amino acids of each other?
Asp and glue
Practice question: Which amino acid makes disulfide bridges?
Cysteine
Practice question: Secondary structure involves ___.
H bonds
Practice question: Which amino acid is never found in alpha helices?
Pro
Practice question: Which level of structure never has covalent bonds?
Secondary
Practice question: Which level of structure involves multiple amino termini and carboxyl termini in R group-R group interactions?
Quaternary
