Question

Select the chiral center(s) in threonine by clicking on the atom(s). (clicking on an atom will turn it green. if you make a mistake, click on the atom again to deselect it.)

Answer 1

Chiral center is the center where all the attached substituents are different. For example, a carbon is said to be chiral carbon if it is attached to four different substituents.

The structure of threonine is attached here.

The marked carbons are chiral carbons because they have all the 4 different substituents.