10.21 Bacterial Genetics – Flashcards
Unlock all answers in this set
Unlock answersquestion
| How big is the bacterial chromosome? |
answer
| 5 million base pairs, 1.3 mm in length (1000x diameter of bacterial cell) |
question
| Are bacteria haploid or diploid? |
answer
| haploid |
question
| How is the bacteiral chromosome packaged? |
answer
| by polyamines spermine and spermidine into a structure called a nucleoid |
question
| T/F The plasmid is replicated at the same time as chromosomal replication. |
answer
| false, plasmid replicates independently (rplicons) |
question
| How big is the bacterial plasmid? |
answer
| 1.5 to >40 kilobases |
question
| What are episomes? |
answer
| plasmids that have integrated into the host bacterium's chromosome |
question
| What types of genes do plasmids encode? |
answer
| virulence determinants or resistance to antibiotics |
question
| T/F A bacterium can have multiple copies of the same plasmid. |
answer
| true |
question
| T/F Bacteriophages are lytic viruses. |
answer
| can be lytic or lysogenic |
question
| T/F Bacteriophage can encode virulence determinants. |
answer
| true |
question
| What type of genome is found in bacteriophages? |
answer
| RNA or DNA |
question
| What is transduction? |
answer
| when bacteria DNA is packaged into phage proteins which then go on to infect another cell. Transduction can be specialized or generalized |
question
| What is transformation? |
answer
| bacteria take up naked dsDNA (either plasmid or chromosomal DNA) from the environment and incorporate it into the genome |
question
| What is a "competent" bacteria? |
answer
| one capable of transformation |
question
| How is competence induced? |
answer
| chemically or electrically |
question
| What is conjugation? |
answer
| transfer of genetic material from donor to recipient (usually plasmid) via a sex pilus |
question
| What type of DNA is transfered via conjugation? |
answer
| ssDNA |
question
| What are simple transposons? |
answer
| insertion sequences; 150-1500 bps and consists of transposase genes flanked on either side by inverted repeats of 15-40 bps |
question
| What are complex transposons? |
answer
| genes in addition ot the transposase are flanked by inverted repeats. Additional genes are usually only for antibioitc resistance or virulence |
question
| What are virulence islands? |
answer
| genes encoding a large number of virulence factors are grouped together and flanked by transposon like mobile elements. Transfered horizontally to other bacteria. |
question
| Name some bacteria that have pathogenicity islands? |
answer
| helicobacter, salmonella, escherichia, vibrio, pseudomonas |
question
| What are the four phases of bacterial growth? |
answer
| lag phase, exponential/log, stationary phase, decline or death phase |
question
| How can you keep bacteria artifically in log phase? |
answer
| chemostat |
question
| What challenges do bacteria in the humna body phase that limits growth? |
answer
| competition for food and space from commensals, innate defense mechanisms (lysozyme, defensins, etc.), oxidative stress from PMNs, iron limitation |
question
| What is sterilization? |
answer
| use of physical procedures or chemical agents to destroy all microbial forms including bacterial spores |
question
| Describe the different ways you can sterilize something? |
answer
| steam under pressure (autoclaving, 121C, 15psi, 20 min), dry heat (160, 2 hrs), UV/ionizing radiation, gas vapors (ethylene oxide or formaldehyde gas) |
question
| How do gas vapors kill bacteria? |
answer
| ethylene oxide or formaldehyde gas kill by substituting alkyl groups for labile hydrogen atoms |
question
| what is disinfection? |
answer
| 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 |
question
| How do chloride compounds like bleach kill bacteria? |
answer
| oxidizing sufhydryl groups on enzymes |
question
| What are two examples of disinfection solutions. |
answer
| chloride compounds (bleach) and phenolic compounds |
question
| What is antisepsis? give exampels. |
answer
| 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 |
question
| Name examples of virulence factors? |
answer
| adhesins, invasins, impedins, aggresins, modulins |
question
| What are adhesins? |
answer
| 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 |
question
| What are invasins? |
answer
| 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 |
question
| What are impedins? |
answer
| 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 |
question
| What are aggresins? |
answer
| moecules that directly damage the host or actively promote the spread of a pathogen; toxins and protases are examples of aggresins |
question
| What are modulins? |
answer
| bacterial components or substances that modulate host cell activity with pathogenic consequences; superantigens are modulines |
question
| What types of bacteria are found in dry skin? |
answer
| staphylococcus epidermidis |
question
| What microorganisms can be found on moist skin? |
answer
| staphylococcus aureus, alpha and nonhemolytic streptococci, diptheroids, and fungi (yeasts primarily; candida) |
question
| What types of bacteria live in hair follicles, sweat and sebaceous glands? |
answer
| proprionibacterium acnes and other anaerobes |
question
| When is the mouth colonized? by what? |
answer
| 4-12 hours after birth by viridans streptococci |
question
| What type of bacterial colonize both the large intestine and the mouth? |
answer
| streptococci (some potential pathogens), staphylococci (also potential pathogens), diptheroids, and gram negative cocci (neiseria, some of which are potential pathogens) |
question
| What fungi do some clinically normal people have in their lungs? |
answer
| PCP |
question
| What is the intestinal flora of a breast fed baby? |
answer
| lactic acid streptococci and lactobacilli |
question
| What type of bacteria live in the stomach? |
answer
| acid tolerant lactobacili and streptococci. also helicobacter pylori |
question
| What type of bacteria are in the upper intestine? |
answer
| lactobacilli and enterococci |
question
| What percent of fecal mass is made up of bacteria? |
answer
| 10-30% |
question
| What types of bacteria are found in the large intestine? |
answer
| anaerobes (bacteroides), facultative anaerobes |
question
| The urethra of both sexes contain what kinds of bacteria? |
answer
| small numbers of the same bacteria found on the skin or perneum (staphylococci, enterococci, diptheroids) |
question
| What is the vaginal flora at birth? |
answer
| lactobacilli (persist as long as the pH remains acidic-several weeks) |
question
| What is bacterial flora of the vagina during childhood? |
answer
| staphylococci, streptococci, diptheroids and E coli |
question
| What is the bacterial flora of the vagina at puberty? |
answer
| lactobacilli, which ferment glycogen to make acid which represses the growth of other organisms |
question
| What vitamins do gut bacteria supply us with? |
answer
| vitamin K and B |
