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Ch 19 & 27, Sources: Urry, L. A., Cain, M. L., Wasserman, S. A.,…
Ch 19 & 27
Replication
Host range:
limited number of species whose cells can be infected by a particular
Lytic Cycle:
type of phage replicative cycle resulting in the release of new phages by lysis of the host cell
Virulent Phage:
phage that replicates only by a lytic cycle
Lysogenic Cycle:
type of phage replicative cycle in which the viral genome becomes incorporated into the bacterial host chromosomes as a prophage; replicated along with the chromosomes and does not kill the host
Temperate Phage:
phage that is capable of replicating by either a lytic or lysogenic cycle
Prophage:
phage genome that has been inserted into a specific site on a bacterial chromosome
Restriction Enzymes:
endonuclease that recognizes and cuts DNA molecules foreign to a bacterium; the enzyme cuts at specific nucleotide sequences (restriction sites),
ex: EcoRI
Retrovirus:
RNA virus that replicates by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome
Reverse Transcriptase:
enzyme coded by certain viruses that uses RNA as a template for DNA synthesis
HIV (human immunodeficiency virus):
infectious agent that causes AIDS; HIV is a retrovirus
AIDS (acquired immunodeficiency syndrome):
symptoms and signs present during the late stages of HIV infection, defined by a specified reduction in the number of T cells and the appearance of characteristic secondary infections
Provirus:
viral genome that is permanently inserted into a host genome
Bacteria and Archaea
Adaptions Contributing to Prokaryotic Success
Peptidoglycan:
type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides
Gram Stain:
staining method that distinguishes between two different kinds of bacterial cell walls; may be used to help determine medical response to an infection
Gram-positive:
group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell wall of gram-negative; usually less toxic than gram-negative
Gram-negative:
bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan than the cell wall of gram-positive bacteria; more toxic
Capsule:
dense and well-defined layer of polysaccharide or protein that surrounds the cell wall and is sticky; enables it to adhere to substrates or other cells
Endospores:
thick-coated resistant cell produced by some bacterial cells when they are exposed to harsh conditions
Fimbria:
short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells
Pili:
a structure that links one cell to another at the start of conjugation
Taxis:
oriented movement toward or away from a stimulus
Nucleoid:
non-membrane-enclosed region in a prokaryotic cell where its chromosome is located
Plasmids:
circular, double-stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome; in DNA cloning, plasmids are used as vectors
Genetic Diversity in Prokaryotes
Transformation:
a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells; a change in genotype and phenotype due to the assimilation of external DNA by a cell
Transduction:
phages carry bacterial DNA from one bacterial cell to another
Conjugation:
prokaryotes - direct transfer of DNA between two cells that are temporarily joined; when the two cells are members of different species, it results in horizontal gene transfer. Ciliates - process which 2 cells exchange haploid micronuclei but do not reproduce
F Factor:
the DNA segment that confers the ability to form pili for conjugation and associated functions required for the transfer of DNA from donor to recipient
F Plasmid:
plasmid form of the f factor
R Plasmid:
bacterial plasmid carrying genes that confer resistance to certain antibiotics
Adaptations
Obligate Aerobe:
organism that requires oxygen for cellular respiration and cannot live without it
Obligate Anaerobe:
organism that carries out only fermentation or anaerobic respiration; cannot use oxygen and in fact may be poisoned by it,
ex: fungi, archaea
Anaerobic Respiration:
catabolic pathway in which inorganic molecules other than oxygen accept electrons at the "downhill" end of electron transport chains
Facultative Anaerobe:
organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present,
ex: salmonella
Nitrogen Fixation:
conversion of atmospheric nitrogen to ammonia; biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants
Heterocyst:
specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria; also called a heterocyte
Biofilms:
surface-coating of one or more species of unicellular organisms that engage in metabolic cooperation; most known biofilms are formed by prokaryotes
Lineages
Extremophiles:
organism that lives in environmental conditions so extreme that few other species can survive there; include extreme halophiles and extreme thermophiles
Extreme Halophile:
organism that lives in a highly saline environment, such as the Great Salt Lake or the Dead Sea
Extreme Thermophile:
organism that thrives in hot environments
Methanogen:
organism that produces methane as a waste product of the way it obtains energy; known methanogens are in domain archaea
Role in the Biosphere
Decomposers:
organism that absorbs nutrients from nonliving organic material such as corpses, fallen plant material, and the wastes of living organisms and converts them to inorganic forms; a detritivore
Symbiosis:
ecological relationship between organisms of 2 different species that live together in direct and intimate contact
Symbiont:
smaller participant in a symbiotic relationship, living in or on the host
Host:
larger participant in a symbiotic relationship; often providing a home and food source for the smaller symbiont
Mutualism:
ecological interaction that benefits individuals of both interacting species
Commensalism:
ecological interaction that benefits the individuals of one species but neither harms nor helps the individual of the other species
Parasitism:
ecological interaction in which one organism, the parasite, benefits by feeding live within the host, while others feed on host's external surface
Parasite:
organism that feeds on the cell contents, tissues, or body fluids of another species while in or on the host organism; harm but usually do not kill their host,
ex: fleas and ticks
Pathogens:
organism or virus that causes disease
Impacts on Humans
Endotoxin:
toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die
Exotoxin:
a toxic protein that is secreted by a prokaryote or other pathogen and that produces specific symptoms, even if the pathogen is no longer present
CRISPR-Cas9 System:
technique for editing genes in living cells, involving a bacterial protein called Cas9 associated with a guide RNA complementary to a gene sequence of interest
Bioremediation:
use of organisms to detoxify and restore polluted and degraded ecosystems
Viruses
Viruses:
infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat and an membranous envelope,
ex: influenza
Capsid:
the protein shell that encloses a viral genome; it may be rod-shaped, polyhedral, or more complex in shape
Viral envelope:
membrane, deprives from membranes of the host cell, that cloaks the capsid, which in turn encloses a viral genome
Bacteriophages:
virus that infects bacteria; also called a phage
Phages:
virus that infect bacteria; also called a bacteriophage
Virises and Prions in Animals and Plants
Vaccine:
harmless variant or derivative of a pathogen that stimulates a host's immune system to mount defenses against the pathogen
Prions:
infectious agent that is a misfiled version of a normal cellular protein; appear to increase in number by converting correctly folded versions of the protein to more prions
Sources: Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., & Reece, J. B. (2017). Campbell Biology (12th ed.). Pearson.