What type of structure do fibrous proteins possess?

Find the correct option for the sequence given below:
$(1)$ Alanine $\rightarrow$ Valine
$(2)$ Asparagine $\rightarrow$ . . . . . .
$(3)$ Aspartic acid $\rightarrow$ Glutamic acid
$(4)$ Arginine $\rightarrow$ Histidine

Based on which group do the properties and types of amino acids differ?

Cysteine and methionine are amino acids containing $........$.

Which of the following is the correct structure of the amino acid cysteine?

Amino acids are those which...