Proteins

Question 1

Dipeptide

Answer 1

2 amino acids

Question 2

Tripeptide

Answer 2

3 amino acids

Question 3

Oligopeptides

Answer 3

4-20 aa’s

Question 4

Formation of peptide bond (mechanism)

Answer 4

Step 1: Nucleophilic attack of deprotonated amino group on carboxilic acid forming tetrahedral intermediate

Step 2: Proton transfer to the leaving group (OH ->H₂O)

Step 3: Water leaves to form new planar amide bond

Question 5

Resonance of the peptide bond

Answer 5

The carboxilic acid C has double bond character between O and N molecules, preventing free rotation between these atoms

Question 6

What is the preferred structural conformation of the peptide bond?

Answer 6

trans conformation

Question 7

Proteases

Answer 7

Cleave peptide bonds in between certain amino acid residues

i.e trypsin cleaves between Lys and Arg

Question 8

Primary structure

Answer 8

The primary structure is the sequence of amino acids that make up a protein

Each protein has its own primary structure

Question 9

Central Dogma of Molecular Biology

Answer 9

DNA –>(transcription) RNA–> (Translation) Proteins

Question 10

Backbone of polypeptide (how to string together tetramer)

Answer 10

N-terminus –> C-terminus

N-(Alpha C)-(Carbonyl C)-N-(Alpha C)-(Carbonyl C)-N…

Question 11

Polyampholyte

Answer 11

Macromolecules containing both acidic and basic groups. polypeptides are polyampholytes in that they are able to donate protons at certain pH values.