prevent already disabled checkbox from being checked when click on checkAll

Below is the code i am using for check all the check boxes.

jQuery("#checkAll").on('click',function() { // bulk checked
            var status = this.checked;
            jQuery(".selectRow").each( function() {
                jQuery(this).prop("checked",status);
            });
        });

But already disabled checkbox is also checked when i click on CheckAll link. How to stop already disabled checkbox from being checked when click on checkAll link? Any help would be greatly appreciated.