Single Celled OrganismsSingle Celled OrganismsPlants & AnimalsPlants & Animals are are multi-celled organismsmulti-celled organisms..– Most cells depend on the other cells in the body to Most cells depend on the other cells in the body to

survive survive (eg: muscle cells require blood cells to bring O(eg: muscle cells require blood cells to bring O22

and remove COand remove CO22))

– Specialized cells carry out their tasks in the Specialized cells carry out their tasks in the organism efficiently, organism efficiently, but cannot carry out all the but cannot carry out all the tasks necessary to survive independentlytasks necessary to survive independently..

Most organisms are single celled organisms– Make up most of the biomass on earth.– By far earth’s dominant life form!

The Protistssingle celled organisms with a nucleus and some other organelles. – Most have mitochondria (cellular respiration)– some may have chloroplasts (photosynthesis)– eg: amoebas, algae

– May be beneficial (algae produces much of the O2 in our atmosphere)

– Some can cause disease (amoebic dysentery, malaria)

amoeba

Bacteriasingle celled organisms without nuclei or other organelles. – First life form to evolve on earth.– Found everywhere and often very

abundant.– Many are mobile

Beneficial uses: – breakdown dead plants and animals– make yogurt– some can photosynthesize

Some can cause disease– infections, strep throat, etc.– Bacterial disease can be treated by

antibiotics (eg: penicillin (mold))

VirusesBundles of DNA in a protein covering.– No nucleus, no organelles

Very small: 0.02-0.3 micrometers– Can only be seen by an electron

microscope

Are not alive.– Do not grow, do not use energy.– Reproduce by attaching to living cell,

injecting it’s DNA into cell. – Cell is forced to produce more viruses.

the flu, colds, warts are all caused by different viruses – (see page 350 for more examples)

Bacterial & Viral Diseases

Disease is fought by body’s immune system. – White blood cells and “antibodies” attack and eat harmful

viruses and bacteria by detecting their “antigens”.

Vaccine = mild form of disease causing bacteria or virus. – Body can successfully fight off vaccine, allows body to form

“antibodies” to fight off more deadly diseases that look similar.

Homework:Homework:Page 350 “Review 15.5” Questions 1-6