Chemical anomalies in globular cluster red giant stars and the "second parameter" problem

We present the evolution of low mass and low metallicity RGB models computed under the assumption of deep mixing between the convective envelope and the hydrogen burning shell. We discuss the helium enrichment of the envelope which is necessary or allowed to achieve or to keep consistency with the observations, and conclude on the possible connection between chemical anomalies in red giants and the horizontal branch morphology in globular clusters.