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Prokaryotes
Dr. David Senchina, Drake University, Medical Microbio notes set 3
68
Microbiology
Undergraduate 2
02/11/2010

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Term
Prokaryote
Definition
A single-celled organism that lacks a nucleus and membrane-bound organelles
Term
What are the differences between Archaea and bacteria?
Definition
Differences in rRNA and tRNA
Unique cell wall/membrane components in archaea
Archaea has repeated gene structures and introns
Archaea has unique shapes
Term
How can prokaryotes be classified?
Definition
Shape
Gram staining
Metabolism
Habitat
Genetics
Term
Cocci
Definition
Sphere-shaped bacteria
Term
Diplococci
Definition
Group of two balls
(Cocci)
Term
Tetrad
Definition
Group of four balls
(Cocci)
Term
Sarcinae
Definition
Groups of eight balls
(Cocci)
Term
Bacilli
Definition
Rod-shaped bacteria
Term
Diplobacilli
Definition
Two rods attached end-to-end
(Bacilli)
Term
Coccobacilli
Definition
Rounded rod-shaped bacteria
(Bacilli)
Term
Strepto-
Definition
Indicates a chain-shaped bacteria
Term
Palisades
Definition
Side-to-side arranged rods, generally not parallel.
(Bacilli)
Term
Spiralla
Definition
Curved or spiral-shaped bacteria
Term
Vibrios
Definition
Curved rods, no rotation (comma-shaped)
(Spiralla)
Term
Spirilla
Definition
Bacteria that rotate at least one helical turn in their shape and have flagella at their polar ends.
(Spiralla)
Term
Spirochete
Definition
Bacteria that have at least three helical turns in their shape, with periplasmic flagella
(Spiralla)
Term
Gram positive
Definition
Bacteria with a thick, exposed layer of peptidoglycan
Term
Gram negative
Definition
Bacteria with a covered layer of peptidoglycan, which the stain cannot attack
Term
Autotroph
Definition
Obtains carbon from inorganic sources
Term
Heterotroph
Definition
Obtains carbon from organic sources
Term
Chemotroph
Definition
Gets energy from chemicals
Term
Phototroph
Definition
Gets energy from light
Term
Obligate aerobes
Definition
Require oxygen to make ATP
Term
Obligate anaerobes
Definition
Require an oxygen-poor environment to make ATP
Term
Facultative anaerobes
Definition
Can live in an aerobic or anaerobic environment
Term
What are the problems with traditional taxonomy?
Definition
Traditional groups into which we classify bacteria can overlap - a specimen may fit into more than one group. Also, species within a group may not be related at all, meaning that a medicine that works on one species can't necessarily be expected to do anything for the rest of the group.
Term
What are the problems with phylogenetic taxonomy?
Definition
To identify an organism phylogenetically, genetic screening has to be run, which takes more time than just looking at an organism or running one or two tests. Also, because it's so new, not many people know it the way they know the traditional system.
Term
Division I prokaryotes
Definition
Gracilicutes
Gram-negative
Term
Division II prokaryotes
Definition
Firmicutes
Gram-positive
Term
Division III prokaryotes
Definition
Tenericutes
No cell wall
Term
Division IV prokaryotes
Definition
Archaebacteria
Term
What types of appendages can be present in prokaryotes?
Definition
Axial filaments or flagella (for movement)
Fimbriae or pili (for attachment)
Term
Flagellum
Definition
A whip-like motility appendage. Comprised of a filament, hook, and basal apparatus.
Term
Monotrichous flagellum
Definition
A flagellum at one polar end of a bacteria
Term
Lophotrichous flagella
Definition
Multiple flagella originating from the same point
Term
Amphitrichous flagella
Definition
Flagella on both polar ends of a bacteria
Term
Peritrichous flagella
Definition
Flagella distributed randomly on the surface of the cell
Term
Peritrichous flagella
Definition
Flagella distributed randomly on the surface of the cell
Term
Periplasmic flagella
Definition
Flagella that are wrapped around the "body" of the bacteria in a spiral fashion
Term
Chemotaxis
Definition
Movement in response to a chemical stimulant
Term
Phototaxis
Definition
Movement in response to light
Term
Fimbriae
Definition
Small, bristle-like appendages for attachment. Used in aggregation or colonization.
Term
Pili
Definition
Appendages for reproduction, generally in gram-negative bacteria. Used to exchange genetic material.
Term
Glycocalyx
Definition
An outer layer of a bacterium composed of macromolecules. It can serve to prevent dessication, protect against immune attacks (by causing antibodies to bind incorrectly), or encouraging colonization.
Term
Biofilm
Definition
A thick layer of accumulated prokaryotes due to fimbriae and glycocalyces. These can be a problem in artificial joints, catheters, and dental hygiene.
Term
Quorum sensing
Definition
The ability of a bacterial colony to "sense" its population density
Term
Cell envelope
Definition
The set of structures that make up an external membrane complex. Includes the cell membrane, cell wall, and outer membrane.
Term
Cell membrane
Definition
Made of phospholipids and proteins, this membrane (in prokaryotes) carries out many of the functions that membrane-bound organelles do in eukaryotes.
Term
Cell wall
Definition
A peptidoglycan structure that serves to maintain cell shape and integrity. Not present in all prokaryotes.
Term
How can peptidoglycan serve as a target for drugs?
Definition
Peptidoglycan is made of polysaccharide strands linked by peptide bonds. Drugs can disrupt those peptide bonds, loosing the strands and dissolving the wall.
Term
Outer membrane
Definition
Structure seen only in gracilicutes. Its outer layer is composed of lipopolysaccharide (LPS), and its inner layer is composed of phospholipids and lipoproteins, which are attached to the cell wall.
Traffic is regulated by porins.
Term
Why do some cell envelope components automatically trigger immune responses?
Definition
Bacteria and humans have been around together a long time, so by now, immune responses to certain bacteria components are ingrained into our DNA.
Term
Cytoplasm
Definition
The inside space of the cell. Comprised of 75% water, plus ribosomes, protein, and other cellular materials, plus a cytoskeleton network.
Term
Nucleoid
Definition
Prokaryotic conglomeration of genetic material. Most have a single loop of DNA, others have extra genes.
Term
Plasmids
Definition
Self-replicating "accessory" DNA that can be stored and shared freely among prokaryotes.
Term
What do plasmids mean for medicine?
Definition
On the one hand, plasmids are bad news, because a virulent bacteria can pass on a drug resistance or toxin-containing plasmid to normally benign bactera, causing a totally new infection. On the other hand, we can engineer plasmids to contain beneficial genes, which we can then impart via bacteria to other organisms.
Term
Ribosome
Definition
Protein-making machinery consisting of a 50S and 30S subunit, made up of rRNA and protein.
Term
Polysome
Definition
A string of ribosomes that make protein from RNA in succession.
Term
Inclusion bodies
Definition
In bacteria, intracellular nutrient stores enclosed by a single-layered membrane. In biology, it's a general term with many meanings.
Term
Cytoskeleton
Definition
An intracellular network of actin filaments that help support the cell's architecture and provide "roadways" for cellular components to move.
Term
Sporulation
Definition
Spore formation due to adverse environmental triggers. Seen in gracilicutes and firmicutes.
Term
Vegetative cell
Definition
Metabolically active cell
Term
Endospore
Definition
Spore form, metabolically inactive
Term
Why sporulate?
Definition
Nutrients are scarce or the environment is wrong
Term
Genus Ricksetta
Definition
Gram-negative prokaryotes that are obligate intracellular (they can't live outside a host). They cause RMSF and a form of typhus.
Term
Genus Chlamydia
Definition
Gram-negative prokaryotes that can't exist outside a host, and were once considered viruses
Term
Genus Mycoplasmia
Definition
Tenericutes, has an outer membrane but no cell wall. Has the smallest bacterial genome known, causes "walking pneumonia" and PID.
Term
Conjugation
Definition
Bacterial "sex" - the exchange of genetic material though pili
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