Chapter 1 Single celled organisms and viruses.


Most living things are too small to observe.  They are called microorganisms-made of one cell. Cell is a basic unit of all living things.

Kingdoms- groups of organisms

Living things increase in size

Binary Fission- way that single-celled organisms reproduce, one cell becomes two.

All living things need energy, materials, and living space

Viruses are not alive.  They do not grow and do not take on energy.  They are able to reproduce by taking over a cell and use it to make new viruses.

Virus has genetic material enclosed in a protein shell.

Bacteria-simplest life on Earth, found in nearly every environment.  One cell without nucleus, reproduces by binary fission. 

Helpful Bacteria

Harmful Bacteria

Break down the matter in dead bodies/soil

Cause disease: invade and poison the cells

Break down sewage


Make nitrogen needed for plants



Archea-single-celled , share characteristics with plants and animals

Methanogens-live in swamps, marshes, guts of animals.  Die when exposed to oxygen.

Halophiles-salty lakes and ponds, die without salt

Thermophiles-hot and cold temps.


Viruses share characteristics with living things, but they are not living organisms

They come in many shapes and sizes

Capsid-protective protein where genetic material is stored

Viruses use living cells to get their DNA copied and reproduce.They do not grow and do not respond to changes in their environment. 

Hosts cells-cells that viruses infect to reproduce

Steps that viruses use to make new viruses:

Attachment-stick to a host cell

Injection-DNA is injected into the host cell

Production-new viruses are produced

Assembly- parts assemble into new viruses

Release-host cell breaks, new viruses are release.

Protists-most complex single-celled organisms with nuclei found on Earth. Most protists are single-celled.  Most diverse of all the kingdoms. 


Algae-plantlike protist, producers, obtain energy from sun.