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Biology chapt 20

Biology Chapter 20

TermDefinition
virus Noncellular parasitic agent consisting of an outer capsid and an inner core of nucleic acid.
capsid Protective protein containing the genetic material of a virus.
bacteriophage Virus that infects bacteria.
lytic cycle Bacteriophage life cycle in which the virus takes over the operation of the bacterium immediately upon entering it and subsequently destroys the bacterium.
lysogenic cycle Bacteriophage life cycle in which the virus incorporates its DNA into that of a bacterium; occurs preliminary to the lytic cycle.
lysogenic cell Cell that contains a prophage (virus incorporated into DNA), which is replicated when the cell divides.
reverse transcriptase Viral enzyme found in retroviruses that is capable of converting their RNA genome into a DNA copy.
emerging viruses Newly identified viruses that are becoming more prominent, usually because they cause serious disease.
viroid Infectious strand of RNA devoid of a capsid and much smaller than a virus.
prion Infectious particle consisting of protein only and no nucleic acid.
neurodegenerative disease Disease, usually caused by a prion, virus, or bacterium, that damages or impairs the function of nervous tissue.prokaryote
prokaryote Organism that lacks the membrane-bound nucleus and the membranous organelles typical of eukaryotes.
binary fission Splitting of a parent cell into two daughter cells; serves as an asexual form of reproduction in bacteria.
conjugation Transfer of genetic material from one cell to another.
conjugation pilus (pl., conjugation pili) In a bacterium, elongated, hollow appendage used to transfer DNA to other cells.
transformation Taking up of extraneous genetic material from the environment by bacteria.
transduction Exchange of DNA between bacteria by means of a bacteriophage.
Bacteria (domain Bacteria) Are the more common type of prokaryote.
peptidoglycan Polysaccharide that contains short chains of amino acids; found in bacterial cell walls.
facultative anaerobes Are able to grow in either the presence or the absence of gaseous oxygen.
obligate anaerobes Are unable to grow in the presence of free oxygen.
photoautotrophs Organism able to synthesize organic molecules by using carbon dioxide as the carbon source and sunlight as the energy source.
chemoautotroph Organism able to synthesize organic molecules by using carbon dioxide as the carbon source and the oxidation of an inorganic substance (such as hydrogen sulfide) as the energy source.
chemoheterotroph Organism that is unable to produce its own organic molecules and therefore requires organic nutrients in its diet.
saprotroph Organism that secretes digestive enzymes and absorbs the resulting nutrients back across the plasma membrane.
mutualism Symbiotic relationship in which both species benefit in terms of growth and reproduction.
commensalism Symbiotic relationship in which one species is benefited, and the other is neither harmed nor benefited.
parasitism Symbiotic relationship in which one species (the parasite) benefits in terms of growth and reproduction to the detriment of the other species (the host).
pathogen Disease-causing agent, such as viruses, parasitic bacteria, fungi, and animals.
endospore Spore formed within a cell; certain bacteria form endospores.
Cyanobacteria (pl., cyanobacteria) Photosynthetic bacterium that contains chlorophyll and releases oxygen; formerly called a blue-greeen alga.
lichen Symbiotic relationship between certain fungi and either cyanobacteria or algae, in which the fungi possibly provide inorganic food or water and the algae or cyanobacteria provide organic food.
Archaea (domain Archaea) Were considered to be a unique group of bacteria.
methanogen Type of archaean that lives in oxygen-free habitats, such as swamps, and releases methane gas.
halophile Type of archaean that lives in extremely salty habitats.
thermoacidophile Type of archaean that lives in hot, acidic, aquatic habitats, such as hot springs or near hydrothermal vents.
Created by: Haleyannestes