Question

model 3 - protein structure (part b)
tertiary structure
quaternary structure
three polypeptide chains
protein structure
a. four types of bonds or interactions are shown. label them with the following terms.
disulfide - bridge
hydrophobic interactions
hydrogen bond
ionic bond
b. describe the part of the amino acid that participates in these interactions.
c. how does your answer in part b differ from the bonds that stabilize the secondary structure?

1. what type of functional groups or atoms would need to be present in the r - groups for hydrogen bonding to occur between two amino acids in a protein chain?
2. what type of functional groups or atoms would need to be present in the r - groups for hydrophobic interactions to occur between two amino acids in a protein chain?
3. how many polypeptide chains are shown in the tertiary protein structure in model 3?

just one

1. many proteins, but not all, have a fourth level of structure termed quaternary structure.

a. how many polypeptide chains are shown in the quaternary structure of the protein in model 3?
3
b. what types of bonds and interactions hold the quaternary structure in place?

• hydrogen bonds
• ionic bonds
• hydrophobic interactions

Explanation:

Step1: Identify bond - labeling task

For part a, match the bond - type terms to the bonds in the model.

Step2: Analyze amino - acid parts for interactions

In part b, the R - groups of amino acids participate in these non - peptide bond interactions.

Step3: Compare with secondary structure bonds

For part c, secondary structure is stabilized by hydrogen bonds between backbone atoms, while these are R - group interactions.

Step4: Determine functional groups for hydrogen bonding

For question 17, functional groups like hydroxyl (-OH), amino (-NH₂) or amido (-CONH₂) in R - groups can participate in hydrogen bonding.

Step5: Determine functional groups for hydrophobic interactions

For question 18, non - polar functional groups like alkyl groups in R - groups lead to hydrophobic interactions.

Step6: Count polypeptide chains in quaternary structure

For question 20a, as seen in the model, there are 3 polypeptide chains in the quaternary structure.

Step7: List bond types in quaternary structure

For question 20b, hydrogen bonds, ionic bonds and hydrophobic interactions hold the quaternary structure in place.

Answer:

a. Match the terms to the bonds in the model as per their structure (disulfide bridge is a covalent S - S bond, hydrogen bond is a weak bond between H and electronegative atom, ionic bond is between charged groups, hydrophobic interactions are between non - polar groups).
b. The R - groups of amino acids participate in these interactions.
c. Secondary structure is stabilized by hydrogen bonds between backbone atoms (N - H and C=O), while these interactions involve R - groups.

1. Hydroxyl (-OH), amino (-NH₂), amido (-CONH₂) etc.
2. Non - polar alkyl groups.
3. One
4. a. Three

b. Hydrogen bonds, ionic bonds, hydrophobic interactions.