proteins- from sequence, to structure, to function

Question 1

what are general functions of proteins?

Answer 1

• enzymes
• structural proteins
• motor proteins
• receptors
• membrane transport proteins
• cytokines and hormones
• carrier proteins
• antibodies

Question 2

explain primary structure (1a)?

Answer 2

its when amino acids are joined by peptide bonds

its written from the N-terminus to the C-terminus

Question 3

explain secondary structure (2a)?

Answer 3

theres 3 types of secondary structure
-alpha helices
-beta pleated sheets
-loops and turns
the amount of rotation in the bonds depends on steric hindrance from the r-groups of amino acids

Question 4

explain tertiary structure of proteins (3a)?

Answer 4

its 3D folding of the secondary structural elements to give the final, native conformation
most proteins have about 30% of each beta-pleated sheets and alpha helixes

Question 5

what are the general rules about tertiary structure in proteins?

Answer 5

• helices and strands run across the protein
• turns and loops are usually at the edge
• the core is densely packed and water is excluded
• the core has some flexibility but the edges are much looser
• cytosolic proteins have polar r-groups on their surface
• membrane proteins have hydrophobic r-groups on their surface

Question 6

in tertiary structure, what are motifs and domains?

Answer 6

motifs-combinations of a few elements of secondary structure

domains-larger structures with discrete functions/activities

Question 7

why are motifs and domains important?

Answer 7

as they help in folding and provide stability to the protein

Question 8

explain quaternary structure (4a)?

Answer 8

it is bonding of multiple subunits to form a protein

Question 9

what is the name of the globular protein that forms fibrous supra-molecular structures?

Answer 9

alpha-tubulin