Let's begin with the similarities
Both bacteria and protozoa are unicellular microscopic organisms. Let's take one example of each to understand the concept better
This is E. coli or Escherichia coli, the most extensively studied microorganism
It has been a model system for the study of bacterial metabolism, the cell division, cell
genetics and even we are synthesizing recombinant proteins inside this bacteria. And this is Paramecium, a well-known model organism of the C-lead group, that is widespread
in fresh water, brackish water or in marine environments. Difference number one regarding the cell structure
Bacteria are prokaryotes and belongs to the kingdom Monera according to the Vikington
classification proposed by Wittaker. So as you see prokaryotes means the genetic material is not surrounded by a membrane
Whereas protozoa are eukaryotes, they are having a two nucleus as you see this genetic
material is surrounded by a nuclear membrane and belongs to the kingdom Protista in Vikington classification
Difference number two. In the case of bacteria, nucleus and other membrane bound organelles are absent
Organs like endoplasmic reticulum called G. podes, mitochondria and etc are absent in bacteria
Whereas in a protozoa, it is a typical eukaryotic cell having all the membrane bound organelles
like ER, coli apparatus, mitochondria, etc. The third difference is regarding the size
Bacteria size ranges from 0.5 to 5 micrometer. It is comparatively smaller to protozoans
Whereas protozoans are large, typically ranging from 5 to 1000 micrometers. Bacteria are present in almost everywhere
They are found in diverse environments, soil, rock, water, hot seltzer springs and even
in Arctic snow. Bacteria that can thrive in hydro bridges are called as thermophiles
Some can tolerate high salinity, they are called as halophiles. Even in moon or Mars exploration, for the presence of life, what we are actually looking
is the presence of bacteria as it can possibly live in almost any condition
Whereas protozoans, they are basically aquatic, and they can live in fresh water, brackish
water or in marine environment. Regarding the mode of nutrition, bacteria are autotrophic, may be photosynthetic like
cyanobacteria or chemosynthetic like biobacillus, or may be heterotrophic, may be saprophytic
parasitic or symbiotic. Symbiotic lies rhizobium that lives in the root nodules of legumes, parasitic in many
organisms also. Whereas protozoans, the mode of nutrition is heterotrophic, the exception is in the
case of euclidna, they are photosynthetic with chloroplast and they are also heterotrophic
They can survive by consuming bacteria, yeast, fungi and algae, they are actually predators
Regarding the reproduction, bacteria, the normal method of reproduction is asexual reproduction
and that is by binary sequence. And there is a primitive form of sexual reproduction which is called as conjugation that is also
happening in bacteria during unbearable conditions. In the case of protozoans, protozoans can produce sexually or asexually sexual reproduction
by syngamy or sexual fusion of gametes, whereas asexual reproduction by budding and binary sequence
And finally, the role of bacteria in an ecosystem, they may be decomposers like bacillus, septalis
and pseudomonas fluorescens or maybe nitrogen fixers like acetobacter, clostridium. Some are pathogens like streptococcus pyogenes that cause strep throat or mycobacterium tuberculosis
that cause TB, so they are of medical importance also. They are disease causing in wide variety of organisms including humans
Whereas protozoans are, some are parasites like Entamoeba histolytica that leads in the
intestine causing intestinal illness, some are predators like paramecium that feeds on
other bacteria and fungus, small group life and etc. And some are pathogens like Plasmodium albitarum that causes Malaria, Taxoplasma gondii that
causes Taxoplasmosis, some are disease causing pathogens also. So, these are the differences between protozoans and bacteria
Hope you are clear. Take care. Stay blessed. Thank you so much
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