What is the relationship between proto-oncogenes and oncogenes? hints what is the relationship between proto-oncogenes and oncogenes? both are involved in arresting the cell cycle. oncogenes are mutant forms of proto-oncogenes. oncogenes are versions of proto-oncogenes that have been permanently switched off. both must be activated to halt cell division?

During crossing-over, a. genetic material is exchanged between nonsister chromatids, resulting in new combinations of alleles. b. nonsister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. c. one homologous chromosome of a tetrad is exchanged with another tetrad, resulting in new combinations of alleles. d. sister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. e. genetic material is exchanged between sister chromatids, resulting in new combinations of alleles.