Explain why viroids can only infect and damage plant cells, but not animal cells. explain why viroids can only infect and damage plant cells, but not animal cells. plant cells contain a rna polymerase that can copy rna can animal cells do not. the genome of plant cells is made of rna while animal cells have a dna genome. animal cells contain rna polymerase that can copy rna and plant cells do not. although both types of cells contain rna, viroids recognize a specific receptor on the surface of plant cells.