prokaryotes
unicellular organisms that lack a nucleus
bacilli
rod-shaped prokaryotes
spirilla
spiral and corkscrew-shaped prokayotes
chemoheterotrophs
takes in organic molecules for both energy and supply energy
photoheterotrophs
a smaller group of hetertrophic prokayotes
photoautotrophs
use light energy to convert carbon dioxide and water to carbon compounds and oxygen in a process similar to that used by green plants
chemoautotrophs
prokayotes can perform chemosynthesis that make organic carbon molecules from carbon dioxide
obligate aerobes
organisms that require a constant supply of oxygen in order to live
obligate anaerobes
they must live in the absence of oxygen
facultative anaerobes
the third group of bacteria can survive with or without oxygen which means the organisms are able to function in different ways
binary fission
when a bacterium has grown so that it has nearly doubled in size, it replicates its DNA and divides in half producing two identical daughter cells
endospore
formed when a bacterium produces a thick internal wall that encloses its DNA and a portion of it cytoplasm
nitrogen fixation
allows nitrogen atoms to continually cycle through the biosphere
viruses
particles of nucleic acid,protein,and in some cases lipids
capsid
a virus's protein coat which includes proteins that enable a virus to enter a host cell
bacteriophages
viruses that infect the bacteria
lytic infection
the host cell is lysed and destroyed
lysogenic infections
a virus integrates its DNA into the DNA of the host cell and the viral genetic information replicates along with the host cell's DNA
prophage
remains part of the DNA is called the host cell for many generations before becoming active
retroviruses
some viruses contain RNA as their genetic information
pathogens
disease-causing agents get all the attention
vaccine
preparation of weakened or killed pathogens
antibiotics
compounds that block the growth and reproduction of bacteria
viroids
single-stranded RNA molecules that have no surrounding capsids
prions
short for "protein infectious particles