Singled-Celled Organisms

ProtistsBacteriaViruses

ProtistsEukaryotes – have a nucleusMost have mitochondria for cellular

respirationMost have chloroplasts to make

their own foodMost live in water

There are good protists and bad protists

 Good protists are able to create O2 through

photosynthesis Bad

protists cause disease in humans

Found in fresh water and ocean

No harmful effects on humans or environment

Bacteria

Smallest and simplest forms of life on the earth

Prokaryotes – do not have a nucleus Do not have most of the organellesHave only 1 DNA molecule which

controls their functions1 spoonful of garden soil may have

1010 bacteria

There are good bacteria and bad bacteria

 Good bacteria make oxygen and

nutrients for other plants and animals

Bad bacteria cause disease in

humans

Bacterial Disease

• Bacteria and Protists that cause disease are called Pathogens.

• Pathogens invade the body of other organism and interfere with the normal cell functions.

Neisseria gonorrhoeae

Salmonella enteriditis

Viruses

Lack most of the characteristics of living cells,therefore most scientists do not call them living cells

Do not move around by themselvesDo not use energyDo not growALL THEY DO IS REPRODUCE!Only have 1 piece of DNA with a

protective coating of protein

How viruses reproduce

• The virus invades another cell, that cell is called a host cell. The virus uses that host’s DNA to reproduce.

Influenza virus

Influenza virus

Herpes Virus

Herpes Virus

Hepatitis B virus causes both acute and chronic liver infections

Rotaviruses infect the lining of the intestine and cause diarrhea ,

especially in children.