neaville's biology-ch.19

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