Campbell Biology- Chapter 27

peptidoglycan

A protein-carbohydrate compound that makes the cell walls of bacteria rigid

gram stain

A staining method that distinguishes between two different kinds of bacterial cell walls.

gram positive

Describing the group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell wall of gram-negative bacteria. Gram-positive bacteria are usually less toxic than gram-negative bacteria.

gram negative

Describing the group of bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan than the cell wall of gram-positive bacteria. Gram-negative bacteria are often more toxic than gram-positive bacteria.

flagellum

a long, hairlike structure that grows out of a cell and enables the cell to move

plasmids

The smalll, circular segments of DNA that are found in bacteria and that stay sparate from the bacterial chromosomes; used in genetic engineering.

endospores

A thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions

transformation

modification of a cell or bacterium by the uptake and incorporation of exogenous DNA

transduction

the process of transfering genetic material from one cell to another by a plasmid or bacteriophage

conjugation

form of sexual reproduction in which paramecia and some prokaryotes exchange genetic information

Obligate aerobes

organisms that require a constant supply of oxygen in order to live

Obligate anaerobes

organisms that cannot live where molecular oxygen is present

anaerobic respiration

Respiration that does not require oxygen

nitrogen fixation

the assimilation of atmospheric nitrogen by soil bacteria and its release for plant use on the death of the bacteria

extremophiles

organisms that survive in extreme environments

extreme thermophiles

Archaebacteria that live in extermely hot environments, such as hydrothermal vents under the ocean

extreme halophiles

Archaebacteria that live in very salty environments, such as the Dead Sea

decomposers

organisms that break down wastes and dead organisms and return raw materials to the environment

symbiosis

relationship in which two species live closely together

host

an animal or plant that nourishes and supports a parasite

symbiont

The smaller participant in a symbiotic relationship, living in or on the host.

mutualism

symbiotic relationship in which both species benefit from the relationship

commensalism

the relation between two different kinds of organisms when one receives benefits from the other without damaging it

parasitism

the relation between two different kinds of organisms in which one receives benefits from the other by causing damage to it (usually not fatal damage)

parasite

an organism that lives in or on another organism; one who lives off another person

pathogens

microbes that cause disease

endotoxins

toxic substances made of lipids and carbohydrates associated with the outer membrane of gram-negative bacteria

exotoxins

toxic substances that bacteria secrete into their environment

bioremediation

the use of living organisms to detoxify and restore polluted and degraded ecosystems

photoautotrophy

use light energy and carbon dioxide to craete energy rich carbon compounds

chemoautotrophy

use inorganic compounds to fix carbon from carbon dioxide

chemoheterotrophy

organisms that use chemicals as a source of energy, and organic compounds as a source of carbon

photoheterotrophy

use of organic compounds as a carbon source during bacterial photosynthesis