PROGRAMS in the Tron universe (or should we say "multiuniverse", since we're dealing with an alternate Earth and its digital counterpart) are alive and conscious. Their appearances mirror that of the ones who wrote them by effect of a "QUANTUM RESONANCE" phenomenon running inbetween the "Real World" (the alternate Earth) and the "Digital World".

TRON Legacy reveals us that it's not just their mere and skin-deep appearances. They have inner functions mirroring ours (they breath "digital air" for instance, or can drink energy or feel sensations by touch) and even a human-like GENETIC CODE embedded into their "digital essence".

Only difference is that they are made of code (digital essence), despite being shaped into anthropomorphic beings featuring digital inner functions and a digital D.N.A sequence embedded into their "essence".

TRON has a D.N.A.
CLU has a D.N.A.
YORI has a D.N.A.
RAM has a D.N.A.
CLU II has a D.N.A.

... and so on.

Each Program has a digital D.N.A. mirroring the human D.N.A. Period. Kevin Flynn even hinted so to Alan Bradley (Alan reported his textual words to Sam at the beginning of the Legacy movie). Kevin confirmed Alan's report later, when explaining the ISOS's history and nature to Sam.

This digital D.N.A. can be exposed via their Identity Disc, which is a "vehicle" to depict their inner essence.

Quorra - and any other ISO - is special and different from common Programs because her digital D.N.A. features a TRIPLE helix, and not a regular double helix.