Question

Some of the strongest biological structures (e.g., beaks and claws) are made of many molecules of the protein keratin. What else is true of structures made of keratin?

(a) Disulfide bridges bind the proteins together.
(b) Each protein is a single long alpha helix.
(c) Hair is another example.
(d) Both (a) and (b).
(e), (b), and (c)."

Answer 1

Keratin is a fibrous protein forming strong biological materials such as beaks, claws, and hair. Disulfide bridges provide integrity and elasticity, and hair is another example of a keratinous structure.

Step-by-step explanation:

Structures made of keratin are significant in the biological world due to their strength and resilience. Keratin is a fibrous protein that forms strong biological materials such as beaks, claws, and hair.

Two characteristics of structures made of keratin are:

1. Disulfide bridges - These covalent bonds, also known as disulfide bonds, form between the sulfur atoms of cysteine residues in keratin proteins. They contribute to the integrity and elasticity of keratinous structures.
   
2. Hair is another common example of a structure composed of keratin. Like beaks and claws, it is made up of fibrous proteins, which contributes to its strength and flexibility.

Each keratin protein is not simply a single long alpha helix; instead, alpha-helices are components of the protein. These helices are extensively cross-linked with disulfide bonds, which enable keratin to maintain structural integrity and elasticity.