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Microbiology Exam III Notes
Study Guide
85
Science
Undergraduate 4
03/27/2012

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Term
Horizontal Gene Transfer
Definition
transfer of genetic material to other individuals other than offsprings (not directly related to them); independent of reproduction
Term
Function of Genes Transferred
Definition

1. gene for infection host

2. gene for metabolizing compounds

3. genes for antibiotic resistance

Term
Mobilome
Definition
genetic elements that can be exchanged with others
Term
Genetic Recombination
Definition
process by which a molecule of nucleic acid is broken and then joined to a different one
Term
Elements of Horizontal Gene Transfer
Definition
plasmids, prophages, islands, random DNA, transposons
Term
Methods of Horizontal Gene Transfer
Definition
transformation, transduction, genomic transfer agents, conjugation
Term
Element
Definition
some piece of DNA that can behave as a unit
Term
Transposable Elements
Definition
DNA sequence that can change its relative position within the genome of a cell; it can do this in a copy and paste method or cut and paste method; these sequences code for transposase; coding region in a transposon is usually flanked by inverted repeats; often produce flanking direct repeats
Term
Simple Transposon
Definition
short DNA sequence and only code for proteins implicated in the transposition activity (transposase that catalyses the enzymatic reaction allowing the transposon to move) and one regulatory protein that either stimulates or inhibits transposition
Term
Composite Transposon
Definition
two insertion sequences that flank other DNA; typically an antibiotic resistance gene is included
Term
Plasmids
Definition
small, typically circular, independently replicating pieces of DNA with useful but not essential information that make up 1 to 10% of the total genome
Term
Types of Plasmids
Definition
fertility, resistance, catabolic, bacteriocin, virulence, tumor-inducing, cryptic
Term
Size of Plasmids
Definition
1 to >1000 kbp single to high copy number plasmids
Term
Fertility Plasmid
Definition
F-plasmid contains genes to make a sex pilus; replicates, and a copy is passed on to another cell
Term
Resistance Plasmid
Definition
genes that make the cell resistant to antibiotics, heavy metals
Term
Catabolic Plasmid
Definition
i.e. tol plasmid with genes for breaking down and using toluene
Term
Bacteriocin Plasmid
Definition
codes for bateriocins, toxins produced bacteria to inhibit the growth of similar or closely related bacterial strains
Term
Virulence Plasmid
Definition
genes needed for the bacterium to infect the host
Term
Tumor-Inducing Plasmid
Definition
The Ti plasmid found in Agrobacterium tumefaciens. Codes for plant growth hormones. When the bacterium infects the plant cell, the plasmid is passed to the plant cell and the genes are expressed, causing local overgrowth of plant tissue = gall. Very useful plasmid for cloning genes into plants
Term
Cryptic Plasmid
Definition
function unknown
Term
Genomic Islands
Definition
sections of DNA separate from the genome; evidence of horizontal origins meaning they are or once were mobile with flanking repeats; contain one or more genes that assist bacterium in pathogenicity, adaption, etc; i.e. P Fimbriae Island in E. coli and SCCmec in Staph aureus
Term
SCCmec
Definition
SCCmec, or staphylococcal cassette chromosome mec, is a mobile genetic element of Staphylococcus bacterial species. This genetic sequence includes the mecA gene coding for resistance to the antibiotic methicillin and is the only known way for Staphylococcus strains to spread the gene in the wild by horizontal gene transfer. Not all SCCmec elements are identical (in fact, SCC elements without the mecA gene do exist.) SCCmec elements have been classified into six types (I through VI) on the basis of two specific regions of their nucleotide sequences. One region is the mec complex including the mecA gene. The other is the ccr gene complex including genes coding for recombinases. The mec complex is divided further into five types (I through V) based on the arrangement of regulatory genetic features such as mecR1, an inducer.
Term
Use of Transferred DNA
Definition
1. nutrient
2. repair of genome damage
3. acquire new genetic information
Term
Transformation
Definition
taking up of naked DNA from solution; occurs in both Gram + and Gram -; due to the negative charge of the cell membrane the negatively charged DNA is unable to enter the cell; cells in a state in which they can take up DNA are called competent; competence can be artificially induced by the introduction of calcium or natural
Term
Transduction
Definition
transfer of DNA from one cell to another by a virus; generalized or specialized
Term
Conjugation
Definition
direct cell-cell transfer of DNA
Term
Generalized Transduction
Definition
typically carries only bacterial DNA; bacterial chromosome DNA is inserted into the viral capsid; occurs in the lytic cycle
Term
Specialized Transduction
Definition
non-viral DNA is carried as an insertion/substitution and into the viral capsid
Term
Conjugation
Definition
bacteria sex
Term
Transfer (tra) genes
Definition
genes necessary for non-sexual transfer of genetic material in both gram-positive and gram-negative bacteria. The tra locus includes the pilin gene and regulatory genes, which together form pili on the cell surface, polymeric proteins that can attach themselves to the surface of F- bacteria and initiate the conjugation
Term
Prophages
Definition
viral genome inserted and integrated into the circular bacterial DNA chromosome
Term
Methods of Bacterial Response to the Environment
Definition
alarmones, cAMP and CRP, alternate sigma factors
Term
Quorum Sensing
Definition
Bacteria produce a constant amount of signal; the more concentrated the bacteria, the more concentrated the signal.
Term
Targets of Traditional Antibiotics
Definition
peptidoglycan synthesis, protein synthesis, DNA replication
Term
Response to Low Nutrient Levels
Definition
induction of low Km uptake system
Term
Siderophores
Definition
acts to sequester and solubilize the iron
Term
Hemolysins
Definition
cause lysis of red blood cells
Term
Bacterial Response to Rapid Drop in Nutrients
Definition
Empty tRNA binds to ribosome
RelA component generates alarmones- (ppGpp which is a global controller)
Protein synthesis stops
Cell division stops
New DNA synthesis stops
Lipid synthesis stops
Resources diverted to amino acid synthesis
Term
Sigma Factors
Definition
protein needed only for initiation of RNA synthesis; a bacterial transcription initiation factor that enables specific binding of RNA polymerase to gene promoters; cascade effect
Term
Types of Taxis
Definition
Positive chemotaxis: attraction towards nutrients
Negative: away from harmful chemicals
Aerotaxis: motility in response to oxygen
Phototaxis: motility to certain wavelengths of light
Magnetotaxis: response to magnetic fields
Term
Whitaker Scheme
Definition
Five kingdoms: Animalia, Plantae, Fungi, Protista, and Monera
(prokaryotes)
Term
Difficulty in Bacterial Classification
Definition
unrelated bacteria develop similar physical and biochemical traits
Term
Differences in Bacteria
Definition
ribosomal RNA genes, membrane lipid chemistry, cell wall chemistry, environment prefrences
Term
Bacterial Species
Definition
a group of strains that are more closely related to each other than to another group. Members of a species have DNA that can hybridize. Because of gene exchange, mutation, phase variation, there are no sharp boundaries between species.
Term
Bacterial Specie Identification Method
Definition
DNA hybridization, ribotyping, DNA sequencing, serotyping (antibodies)
Term
Hyperthermophilic Gram Negatives
Definition
grow at >70 degrees
Term
Green Sulfur and Green Non-Sulfur Bacteria
Definition
photosynthetic, anoxygenic, sulfur bacteria uses H2S as electron donor
Term
Deinococcus
Definition
highly radiation resistant; great DNA repair
Term
Cyanobacteria
Definition
blue-green algae; oxygenic photosynthesis
Term
Proteobacteria
Definition
largest group of Gram - bacteria, enteric bacteria, vibria, pseudomonas (strictly respiratory), groups affecting N and sulfur cycles, purple sulfur and purple non-sulfur anoxygenic phototrophs, rickettsia (obligate intracellular parasite)
Term
Bacteroides and Cytophaga
Definition
bacteroides strict anaerobes
cytophaga aerobic and gliding
Term
Gram + Bacteria
Definition
Endospore formers (Bacillus, Clostridium)
Cocci (Staph, Strep, Micrococcus)
Other rods (Mycobacteria, Listeria, etc.)
Actinomycetes (filamentous, antibiotic producers)
Mycoplasma (DNA says G+, but no cell wall)
Term
Spirochetes
Definition
tight spirals, internal flagell, G-
Term
Chlamydia
Definition
obligate intracellular parasite
Term
Methanogens and Halophiles
Definition
Methanogens strict anaerobes, make methane; Exist as symbiotes with mammals, e.g. cows
Halophiles need at least 1.5 M salt
Term
Hyperthermophiles
Definition
Growth from 80 upwards to 120 degrees C
Term
Woese's Scheme
Definition
based on rRNA; 3 kingdoms
Term
Mycology
Definition
study of fungus
Term
Saprotrophs
Definition
decay non-living organic matte; i.e. fungi
Term
Heterotrophs
Definition
use pre-formed organic matter; not autotrophs and not photosynthetic
Term
Fungi Absorption of Nutrients
Definition
release extracellular enzymes, break down polymers into LMW compounds for transport
Term
Fungi Reproduction
Definition
sexual and asexual
Term
Deuteromycota/ Fungi Imperfecti
Definition
fungi that can not be coaxed into having sex and cannot be properly classified
Term
Hypha
Definition
thread; may be partially separated into cells or not at all (ceonocytic); tubular; composed of chitin; multinucleate; grow at tips
Term
Mycelium
Definition
a mass of hyphae
Term
Yeast
Definition
oval, unicellular
Term
Dimorphic Fungi
Definition
able to grow as mold or yeast
Term
Reproduction by Spores
Definition
can be sexual or asexual; formed directly on hyphae, inside sporangia, or fruiting bodies
Term
Mycosis
Definition
disease by fungus; infection; most are saprotrophs
Term
Antibiotic Production by Fungus
Definition
penicillium, cephalosporium
Term
Function of Fungi in Food Industry
Definition
soy sauce and cheeses
Term
Function of Fungi in Decomposition
Definition
Cellulose and other plant polymers, wood
stone, paintings, paint, plastic
Term
Mycorrhizae
Definition
“Fungus roots”
Mutualism between:
Fungus (nutrient & water uptake for plant)
Plant (carbohydrate for fungus)
Several kinds
Zygomycota – hyphae invade root cells
Ascomycota & Basidiomycota – hyphae invade root but don’t penetrate cells
Term
Ecological Succession
Definition
Aerobic bacteria use up O2, anaerobes begin to grow; Degradation in compost raises temperature; thermophiles take over; Fermentation lowers pH and produces acids which are good nutrient sources for aerobes
Term
Carbon Cycle
Definition
Photoautotrophic bacteria fix CO2, heterotrophs release it
Large geological reservoirs; carbons moves quickly through living things; in anoxic region polysaccharides are broken down to sugar then organic acids, the organic acids are dehydrolyzed in the oxic region and converted into carbon dioxide
Term
Nitrogen Cycle
Definition
Multiple redox states of N, moves through soil, water, air; Degradation of organic N from biomass releases ammonia;
Ammonia oxidized to nitrite for energy (e.g. Nitrosomonas)
Nitrite oxidized to nitrate for energy (e.g. Nitrobacter)
Nitrate N can be used by plants.
Term
Phosphorous Cylce
Definition
Mostly as phosphate; removed from rocks and cycled
Term
Assimilation
Definition
Sulfate reduced to sulfide for amino acids
Ammonium released from organics for amino acids
Reactions occur to the extent needed for biomass
Term
Dissimilation
Definition
Sulfate serves as electron sink, converted to sulfide
Ammonium serves as energy source, is oxidized
Amino acids broken down for carbon, excess N excreted
Dissimilation: much larger quantities of chemicals converted into different forms.
Term
Biofilm
Definition
Surface may be a nutrient source
Organic molecules absorb to surfaces, also
Multiple species with different niches represented
Cells use fimbriae and slime to adhere
Channels allow diffusion of nutrients (in) and waste (out)
Quorum sensing helps direct remodeling of structure
Changes in gene regulation; e.g. loss of flagella
Cells move within biofilm; cells and pieces of biofilm can leave and colonize new areas
Part of food web; provide nutrients for protozoa
Term
Industrial use of Biofilms
Definition
Plug pipes, stimulate corrosion, impair heat exchangers
Biocides less effective; only surface layers killed
Term
Medical use of Biofilms
Definition
Infections can lead to colonization of artificial structures
Heart valves; seed infections elsewhere in the body
Difficult for antibiotics to completely rid infection
Term
Enrichment Culture
Definition
Increasing the size of a specific population by specifying what nutrients it can use
To find a bacterium in a mixed population that can:
Use phenol: supply phenol as sole carbon source
Use N2 as N source: provide no other N
Term
Winogradsky Column
Definition
anaerobic bacteria break down cellulose into glucose subunits and partially break it down by fermentation producing ethanol and other organic acids as by-products; H2S used by green sulfur bacteria (tolerates higher S concentration than purple) and purple sulfur bacteria and use CO2 as the carbon source and H2S as an electron donor; aerobic bacteria= cyanobacteria and algae
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