We use the constituent quark model to extract polarized parton distributions and finally polarized nucleon structure function. Due to limited experimental data which do not cover whole (x,Q2) plane and to increase the reliability of the fitting, we employ the Jacobi orthogonal polynomials expansion. It will be possible to extract the polarized structure functions for Helium, using the convolution of the nucleon polarized structure functions with the light cone moment distribution. The results are in good agreement with available experimental data and some theoretical models.

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