Final answer:
An intact T-cell receptor has six complementarity-determining regions (CDRs), with three CDRs on each of the two chains, that contribute to the antigen-binding site.
Step-by-step explanation:
The T-cell receptor (TCR) is comprised of two chains, each having a variable region that is essential for antigen binding. There are three complementarity-determining regions (CDRs) on each chain within the variable regions. These CDRs are hypervariable regions that contribute to the formation of the antigen-binding site. Therefore, an intact T-cell receptor has a total of 6 CDRs that determine its antigenic specificity, with three on each of the two chains (α and β chains).