01. Molecular Structures — RNA & Proteins

Question 1

What are some secondary conformations of RNA?

Answer 1

• RNA molecules typically fold onto themselve; complementary sequences within strands
• G;U — non-Watson-Crick base pairing is possible
• Stem-loops and hairpin loops can form as a result:

Question 2

What are some tertiary conformations of RNA?

Answer 2

• Triple base pairing
• Coaxial rotations around non-base paired segments
• Pseudoknots around non-adjacent complementary regions
• A-minor, tetraloop

Question 3

What are some R-group properties?

Answer 3

• Enzymatic activity
• Charges
• H-bonding
• Modification sites

Question 4

What are the primary, secondary, and tertiary/quaternary structures of proteins?

Answer 4

1. Polypeptide
2. Alpha-helix or beta-pleated sheet
3. Protein

Question 5

Describe some posttranslational protein modifications. (Aside from ubiquitination).

Answer 5

• Phosphorylation
  
  • Regulatory
  • Transient removal or addition of a Pi to an enzyme (activation purposes)
  • Kinases — add Pi to the enzyme
  • Phosphorylase — transfers it back to ATP
• Sulfation
  
  • Permanent
• Acylation
  
  • Addition of acetyl group to N-terminus
• Glycosilation
  
  • Addition of various sugars
  • Useful for identification on cell surface
• Methylation
• Prenylation
  
  • Addition of fatty acids
• Vitamin C-Dependant
• Vitamin K-Dependant

Question 6

Describe ubiquitination.

Answer 6

• Ubiquitin protein is covalently added to a protein.
• Can mark it for transport (mono) or proteolysis (poly).
• Helps regulate protein stability.