Objectives

!  Describe the general characteristics and environmental role of protists

!  Describe the general characteristics of bacteria

!  Describe the general characteristics of viruses

!  Differentiate between DNA and RNA viruses

More than meets the eye! !  There is more biodiversity than we can

see with the naked eye. !  The study of organisms that cannot be

seen with the naked eye is called Microbiology

!  Three major types of organisms: !  Protists !  Bacteria !  Viruses

Meet the protists! !  Protists are:

!  Eukaryotes !  Autotrophs or Heterotrophs !  Unicellular or Colonial

!  Types of protists !  Animal-like - heterotrophs

!  Examples: Trichomonas, amoeba, paramecium

!  Plant-like – have chloroplasts, so autotrophs !  Examples: Euglena, diatoms, algae

!  Fungus-like – decomposers, so heterotrophs !  Examples: Slimemolds, watermolds

Why protists? !  Environmental role of protists:

!  Producers: convert carbon dioxide to oxygen !  Some parasitic

!  Example: Plasmodium (the cause of malaria) !  Decomposers: recycle nutrients !  Base of aquatic food chains

!  Example: zooplankton

Hello, Bacteria! !  There are 3 main shapes of

bacteria: !  Bacilli: These are rod-

shaped bacteria. !  Cocci: These are sphere-

shaped bacteria. !  Streptococci are chains of cocci

bacteria. !  Staphylococci are clusters of

cocci bacteria.

!  Spirilla: These are spiral-shaped bacteria.

Characteristics of Bacteria !  Most bacteria have certain commonalities.

!  Most bacteria have a cell wall (like plant cells.) !  Just like every other type of cell, bacteria cells have a

cell membrane and cytoplasm. !  Bacteria do NOT have a membrane-bound nucleus,

but have a nucloid region where DNA is stored. !  Like all living things, bacteria need a food source for

energy, however, some are autotrophs and others are heterotrophs.

!  Bacteria have the ability to replicate, but do not undergo mitosis.

!  One way that scientists identify bacteria is by peptidoglycan !  Present = gram-positive; Absent = gram-negative

Is there good bacteria? !  Yes! Some bacteria are good for:

!  Providing oxygen (producers) !  Recycling nutrients (decomposers) !  Food production (Example: yogurt) !  Nitrogen fixation (Example: Rhizobium) !  Medicine (Some archaeabacteria)

!  Bacteria even have a mutualistic relationship with humans! !  Escheria coli lives in our guts and helps us to

digest!

I am Virus! !  A virus is a nonliving particle that is made

up of nucleic acid and either a protein coat or a lipoprotein coat.

!  Viruses are classified by whether they contain DNA or RNA (double or single stranded), by their protein coat (capsid), and whether or not they have a bilipid membrane (envelope.) !  A virus made up of RNA is considered a

retrovirus (Example: AIDS) !  Viruses can replicate, but require a host cell

in order to do so.

Not Living?!? !  Viruses are not alive because:

!  They are not made up of cells !  They rely on the host cell for respiration,

nutrition, and reproduction !  They do not grow !  Do not react to the environment

!  But viruses are able to evolve!

Viral Replication !   Viruses enter the host

cell and introduce the RNA or DNA.

!   That genetic material is inserted into the genetic material of the host cell.

!   Once the genetic material has been altered, transcription and translation will occur in the cell using the new “infected” DNA or RNA.

Common Viral Diseases

Objectives !  Describe the general characteristics and

environmental role of protists

!  Describe the general characteristics of bacteria

!  Describe the general characteristics of viruses

!  Differentiate between DNA and RNA viruses