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10.21 Bacterial Genetics
10:00 by Dr. Hobden
53
Microbiology
Professional
10/24/2011

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Term
How big is the bacterial chromosome?
Definition
5 million base pairs, 1.3 mm in length (1000x diameter of bacterial cell)
Term
Are bacteria haploid or diploid?
Definition
haploid
Term
How is the bacteiral chromosome packaged?
Definition
by polyamines spermine and spermidine into a structure called a nucleoid
Term
T/F The plasmid is replicated at the same time as chromosomal replication.
Definition
false, plasmid replicates independently (rplicons)
Term
How big is the bacterial plasmid?
Definition
1.5 to >40 kilobases
Term
What are episomes?
Definition
plasmids that have integrated into the host bacterium's chromosome
Term
What types of genes do plasmids encode?
Definition
virulence determinants or resistance to antibiotics
Term
T/F A bacterium can have multiple copies of the same plasmid.
Definition
true
Term
T/F Bacteriophages are lytic viruses.
Definition
can be lytic or lysogenic
Term
T/F Bacteriophage can encode virulence determinants.
Definition
true
Term
What type of genome is found in bacteriophages?
Definition
RNA or DNA
Term
What is transduction?
Definition
when bacteria DNA is packaged into phage proteins which then go on to infect another cell. Transduction can be specialized or generalized
Term
What is transformation?
Definition
bacteria take up naked dsDNA (either plasmid or chromosomal DNA) from the environment and incorporate it into the genome
Term
What is a "competent" bacteria?
Definition
one capable of transformation
Term
How is competence induced?
Definition
chemically or electrically
Term
What is conjugation?
Definition
transfer of genetic material from donor to recipient (usually plasmid) via a sex pilus
Term
What type of DNA is transfered via conjugation?
Definition
ssDNA
Term
What are simple transposons?
Definition
insertion sequences; 150-1500 bps and consists of transposase genes flanked on either side by inverted repeats of 15-40 bps
Term
What are complex transposons?
Definition
genes in addition ot the transposase are flanked by inverted repeats. Additional genes are usually only for antibioitc resistance or virulence
Term
What are virulence islands?
Definition
genes encoding a large number of virulence factors are grouped together and flanked by transposon like mobile elements. Transfered horizontally to other bacteria.
Term
Name some bacteria that have pathogenicity islands?
Definition
helicobacter, salmonella, escherichia, vibrio, pseudomonas
Term
What are the four phases of bacterial growth?
Definition
lag phase, exponential/log, stationary phase, decline or death phase
Term
How can you keep bacteria artifically in log phase?
Definition
chemostat
Term
What challenges do bacteria in the humna body phase that limits growth?
Definition
competition for food and space from commensals, innate defense mechanisms (lysozyme, defensins, etc.), oxidative stress from PMNs, iron limitation
Term
What is sterilization?
Definition
use of physical procedures or chemical agents to destroy all microbial forms including bacterial spores
Term
Describe the different ways you can sterilize something?
Definition
steam under pressure (autoclaving, 121C, 15psi, 20 min), dry heat (160, 2 hrs), UV/ionizing radiation, gas vapors (ethylene oxide or formaldehyde gas)
Term
How do gas vapors kill bacteria?
Definition
ethylene oxide or formaldehyde gas kill by substituting alkyl groups for labile hydrogen atoms
Term
what is disinfection?
Definition
use of physical procedures or chemical agents to destroy MOST microbial forms; bacterial spores, mycobacteria, viruses, and fungi may remain viable depending on the disinfectant used and the environmental conditions
Term
How do chloride compounds like bleach kill bacteria?
Definition
oxidizing sufhydryl groups on enzymes
Term
What are two examples of disinfection solutions.
Definition
chloride compounds (bleach) and phenolic compounds
Term
What is antisepsis? give exampels.
Definition
use of chemical agents (ethyl or isopropyl alcohol and iodophors) on skin or other living tissue to inhibit or eliminate microbes; no sporocidal activity implied
Term
Name examples of virulence factors?
Definition
adhesins, invasins, impedins, aggresins, modulins
Term
What are adhesins?
Definition
bacterial proteins that allow the microbe to bind to a variety of eukaryotic cells, thereby preventing them from being removed by washing or flushing actions; pili and some outer membrane porteins are examples of adhesins
Term
What are invasins?
Definition
bacterial proteins that allow a microbe to enter eukaryotic cells; allowing them to be safe from complement mediated killing intracellularly and some antibiotics cannot penetrate eukaryotic cell membranes
Term
What are impedins?
Definition
bacterial components which inhibit the operation of host defense mechanisms without actually doing any damage to the host; antiphagocytic capsules or antibody binding proteins (protein A or G) are impedins
Term
What are aggresins?
Definition
moecules that directly damage the host or actively promote the spread of a pathogen; toxins and protases are examples of aggresins
Term
What are modulins?
Definition
bacterial components or substances that modulate host cell activity with pathogenic consequences; superantigens are modulines
Term
What types of bacteria are found in dry skin?
Definition
staphylococcus epidermidis
Term
What microorganisms can be found on moist skin?
Definition
staphylococcus aureus, alpha and nonhemolytic streptococci, diptheroids, and fungi (yeasts primarily; candida)
Term
What types of bacteria live in hair follicles, sweat and sebaceous glands?
Definition
proprionibacterium acnes and other anaerobes
Term
When is the mouth colonized? by what?
Definition
4-12 hours after birth by viridans streptococci
Term
What type of bacterial colonize both the large intestine and the mouth?
Definition
streptococci (some potential pathogens), staphylococci (also potential pathogens), diptheroids, and gram negative cocci (neiseria, some of which are potential pathogens)
Term
What fungi do some clinically normal people have in their lungs?
Definition
PCP
Term
What is the intestinal flora of a breast fed baby?
Definition
lactic acid streptococci and lactobacilli
Term
What type of bacteria live in the stomach?
Definition
acid tolerant lactobacili and streptococci. also helicobacter pylori
Term
What type of bacteria are in the upper intestine?
Definition
lactobacilli and enterococci
Term
What percent of fecal mass is made up of bacteria?
Definition
10-30%
Term
What types of bacteria are found in the large intestine?
Definition
anaerobes (bacteroides), facultative anaerobes
Term
The urethra of both sexes contain what kinds of bacteria?
Definition
small numbers of the same bacteria found on the skin or perneum (staphylococci, enterococci, diptheroids)
Term
What is the vaginal flora at birth?
Definition
lactobacilli (persist as long as the pH remains acidic-several weeks)
Term
What is bacterial flora of the vagina during childhood?
Definition
staphylococci, streptococci, diptheroids and E coli
Term
What is the bacterial flora of the vagina at puberty?
Definition
lactobacilli, which ferment glycogen to make acid which represses the growth of other organisms
Term
What vitamins do gut bacteria supply us with?
Definition
vitamin K and B
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