Protists include all unicellular and colonial eukaryotes except those of green and red algae. They are broadly divided into three groups - photosynthetic, slime moulds and protozoans. The protistan cells are typically eukaryotic having membrane bound organelles like mitochondria, chloroplasts, Golgi bodies, endoplasmic reticulum, nucleus etc. Nucleus is well defined. The genetic material is DNA, enclosed by nuclear envelope, complexed with proteins and organised into distinct chromosomes.