$A$ lubricant,mucin in saliva,is made up of:

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

Which of the following is the most abundant protein in the animals?

The antibodies in our body are complex $ \dots $.

What is the quaternary structure of a protein?

Identify the mismatched pair regarding amino acid properties.