Microbiology BIOL 305 Exam 2 study guide

Know examples of alphaproteobacteria, betaproteobacteria, and gammaproteobacteria.

(*α*): *Rickettsia* rickettsii (Rocky Mountain spotted fever), *Rhizobium* (fixes N on plant roots), Agrobacteria (insert plasmids into plant cells causing a tumor) (*β*): Bordatella pertussis (whooping cough), Neisseria gonorrhea, Neisseria meningitides (meningitis) (*ɣ*): Francisella tularensis (rabbit fever), *Escherichia coli*, *Salmonella* enterica (food poisoning)

What is a base analog?, frameshift mutation? Mutagen vs spontaneous mutation?

*Base analog:* a chemical that resembles a nucleotide base and substitutes purine and pyrimidine bases that normally appear in DNA, despite minor differences in structure. This may be used for inducing mutations, including point mutations. *Frameshift mutation:* the insertion or deletion of one or more nucleotide pairs, shifts the translational "reading frame" *Mutagen:* an agent that causes mutations ("induced mutations") *Spontaneous mutation:* occurs in the absence of a mutagen

What is unusual about the Bdellovibrios? The Chlamydia? Rickettsia? Helicobacter?

*Bdellovibrio*: belongs to the class of deltaproteobacteria, which are bacteria that are pathogenic to OTHER bacteria! They prey on other bacteria! *Chlamydia*: a phylum of nonproteobacteria. C.trachomatis is the STD, and it can cause blindness. They are special because they have an unusual life cycle. The "elementary body" attaches to a host cell, the host cell engulfs the elementary body into a vacuole, the elementary body reorganizes to form a "reticulate body", the reticulate body divides into more reticulate bodies, the reticulate bodies begin to convert BACK to elementary bodies, and the elementary bodies are released from the host cell. *Rickettsia*: belongs to the class of alphaproteobacteria, it forms arthropod-bourne, spotted fevers. It is an obligate intracellular parasite, meaning that it can only grow inside a eukaryotic cell. It enters a cell by being engulfed and grows within the host cell. R. rickettsii is Rocky Mountain spotted fever, which infects white blood cells (and that can cause a rash). *Helicobacter*: belongs to the class of epsilon proteobacteria, which are organisms that are slender and helically shaped. Helicobacter in particular have multiple flagella. Helicobacter pylori (*H.pylori*) is curve-rod shaped and causes gastritis and peptic ulcers in humans.

What is the difference between a culture, a clone and a strain?

*Culture:* grown in laboratory media *Clone:* population of cells derived from a single cell *Strain:* genetically different cells within a clone

How do physical antimicrobial agents act? What do they do to cells?

*Disinfectants* are chemicals used on inanimate objects and destroys vegetative microbes. *Antiseptics* are disinfectants that don't destroy living tissues.

What is an ELISA, flow cytometry?

*ELISA*, or Enzyme-linked immunosorbent assay, is a serological test that can detect the presence of known antibodies and an unknown type of bacteria added to a well. The reaction that takes place thereafter identifies the bacteria. *Flow cytometry* refers to testing by using differences in electrical conductivity between species (this is typically used for organisms that cannot be cultured) to separate cells by electrical charge. Some of the cells studied naturally are fluorescent, and we can see this by staining to observe the organism's shape and size, and can further identify them by analyzing its DNA.

Know the order of decreasing resistance of microorganisms to chemical microbiocides.

*Most resistant to microbiocides* Prions Bacterial Endospores Mycobacteria Protozoa cysts Vegetative Protozoa Gram-negative bacteria Fungi & most fungi spores Viruses without envelopes Gram-positive bacteria Viruses with lipid envelopes *Most susceptible to microbiocides*

What is PCR and How is PCR used to help classify organisms?

*PCR*, or polymerase chain reaction, is used to make multiple copies of a piece of DNA enzymatically. This method is used to clone DNA (for recombination), amplify DNA to detectable levels, sequence DNA, diagnose a genetic disease, and to detect pathogens (NAAT test)

What is taxonomy and phylogeny

*Taxonomy:* The science of classifying organisms. The goal is to depict relationships between organisms grouped together. *Phylogeny:* The study of the evolutionary history of organisms.

What are trophozoite, schizogony, gamogony, sporogony?

*Trophozoite:* The vegetative form of a protozoa *Schizogony:* another word for asexual reproduction by fission or budding *Gamogony:* Differentiation of haploid cells into male and female gametes capable of fertalization *Sporogony:* Mitotic reproduction and development of the diploid zygote into a spore-like form transmissible to the next host

List some common Gram-positive bacteria genuses:

- Clostridium - Bacillus - Staphylococcus - Lactobacillus - Streptococcus - Enterococcus - Listeria - Mycoplasma (no cell wall) - Mycobacterium - Streptomyces

How is RNA different/same as DNA?

- In RNA, Uracil replaces Thymine - RNA has ribose instead of deoxyribose - RNA is complementary to DNA - The information in DNA is passed to RNA

What are the principles of effective disinfection?

- Microorganisms involved - Degree of contamination - *Concentration of disinfectant* - Strength of disinfectant - Mechanism of action of the chemical - Presence of *organic matter* - How will the disinfectant come in contact with the microbe - Temperature and *pH* of the chemical solution - Nature of the material being disinfected - *Time*, length of exposure to disinfectant

Fungal Growth characteristics:

- Their optimal pH level is around 5, lower than that of bacteria. - They are more resistant to high osmotic pressure than are bacteria. They can grow in high sugar or salt. - Can grow in low moisture - Require less Nitrogen than bacteria - Can metabolize complex carbohydrates (unlike bacteria)

Characteristics of Protozoa:

- Unicellular animal cells - Chemoautotrophs - Acquire food by absorption/ingestion - They have motility - Some form cysts

How does dry heat work? How does moist heat work?

---*Dry Heat:* kills by oxidation. Methods include flaming, incineration, and hot-air sterilization. ---*Moist Heat:* denatures proteins. *Boiling* at 100 °C at sea level for 10 minutes breaks H-bonds in proteins, and kills most vegetative cells, fungi, and some viruses (however, to kill spores by boiling, it takes longer). Boiling disinfects, but does NOT sterilize. *Autoclaving* uses steam under pressure to sterilize the surface of an item. *Pasteurization* is the use of heat to reduce spoilage organisms and pathogens.

What happens during the phases of growth of a bacterial culture?

1. *Lag Phase*: increase in cell's size and cell division, intense increased metabolic activity, sensitive to physical and chemical damage. 2. *Log Phase*/Exponential: maximal growth and cell division, cells double at fastest rate, cell size is slightly decreased, increased metabolic activity, and sensitive to physical and chemical damage. 3. *Stationary Phase*: when the growth rate eventually decreases then stops. The number of new cells = the number of dead cells, nutrients are depleted, formation of metabolic byproducts. 4. *Death Phase*/Decline: whole cell culture dies at first slowly, then exponentially.

List the six major physical methods used to control microbial growth.

1. Moist Heat (Autoclave, Pasteurization) 2. Dry Heat 3. Filtration 4. Desiccation 5. Osmotic Pressure (Plasmolysis) 6. Radiation (Also, cold temperatures inhibit microbial growth)

What are the three ways DNA is transferred from one bacterium to another bacterium? What is meant by horizontal transfer?

1. Transformation: naked DNA taken up by a cell 2. Conjugation: cell-to-cell contact via a pili 3. Transduction: DNA transfer that occurs by viral transfer, like bacteriophages *Horizontal Transfer* is the transfer of genes between cells of the same generation (ew incest!!)

What are the 3 steps of translation? How is translation terminated?

1. mRNA is translated in codons, a three nucleotide code per amino acid 2. Translation of mRNA begins at the start codon: AUG 3. Translation ends at a *stop codon*: UAA, UAG, or UGA

What are the requirements for growth?

Chemical requirements include: Carbon, Nitrogen, Sulfur, and Phosphorus, Oxygen and water, and an organic growth factor.

All new nucleic acid is synthesized in a ____________ direction.

5' to 3'

What is a transposon? An insertion sequence?

A *transposon* is a segment of DNA that can move from one region of DNA to another (spooky!). Bacterial chromosomes contain *insertion sequences* for cutting and resealing DNA (transposase).

What are codons, anticodons, start codon, stop codons?

A codon is a three nucleotide sequence that codes for an amino acid. An anticodon is the complementary codon carried by the tRNA with the right amino acid. The start codon (AUG) is where translation begins, and the stop codon (UAA, UAG, or UGA) is where translation ends.

What is a germicide? What is a germ?

A germicide is a chemical agent that kills microbes, but not necessarily the endospores. A "germ" is a pathogen. Some germicides include bactericides, sporicides, virucides, and fungicides.

What is a plasmid? What are its structure and its function?

A plasmid is a circular, self-replicating piece of DNA. Sometimes there is no function or the function is unknown. However, the "f" factor influences cell mating, conjugation, and sometimes carries resistance genes.

What is a promoter?

A promoter is something specific for the RNA polymerase, a promoter sequence: DNA TAC RNA *AUG*

What is a proteobacterium?

All proteobacteria are Gram negative, chemoheterotrophic, can grow in low levels of nutrients, is the largest taxonomic group of bacteria, does not fix CO2, and includes five classes. Genuses include: - Bartonella, Brucella, Ehrlichia, *Rickettsia* (α) - Azospirillum, *Rhizobium* (α) - Burkholderia, Bordatella, Neisseria (β) - Francisella, Pseudomonales, Legionalles, Vibrionales, Enterobacteriales (*Escherichia*, *Salmonella*, Serratia) (ɣ) - Bdellovibrio (δ) - Campylobacter, Helicobacter (ε)

What is the generation time?

Also known as "doubling time", it's the time required for a cell to divide (20 minutes to 24 hours). Binary Fission *doubles* the number of cells in each generation, making the total number of cells 2^number of generations Since this is exponential, growth curves are represented logarithmically.

Why is GC content important?

At high temperatures, DNA can be denatured because it weakens the hydrogen bonds between base pairs. However, it has been found that some DNA strands take longer to denature than others, and that is usually due to a *high GC content*. AT and TA pairs are formed by two hydrogen bonds, while CG GC pairs are formed by THREE H-bonds, thus making the GC bonds stronger than AT bonds and harder to break.

Do firmicutes make endospores? Do bacillus and clostridium have endospores?

Bacillus and Clostridium are firmicutes that can make endospores. Lactobacillales like Lactobacillus, Streptococcus, Enterococcus, and Listeria are firmicutes that can NOT make endospores.

What is a base substitution? What is a silent, missense or nonsense mutation?

Base substitution: "point mutation", it's when there is a change in one base Silent mutation: when a base substitution does NOT result in the change of an amino acid Missense mutation: when a base substitution results in the change of an amino acid Nonsense mutation: a base substitution that results in a stop codon

What is the life-cycle characteristic that Chlamydiae and Rickettsiae share?

Both groups are *obligate intracellular parasites*.

Is "cold" bacteriostatic or bactericidal? How about desiccation, filtration, and osmotic pressure?

Cold: bacteriostatic (inhibits bacterial growth) Desiccation: bacteriostatic (the removal of water, bacteria with capsules can withstand it for awhile) Filtration: bactericidal (bacteria are removed from nutrient source and eventually die) High Osmotic Pressure: bacteriostatic (because some molds and algae can grow at higher osmotic pressure)

What happens in conjugation? How?

Conjugation is basically "cell mating". Conjugating cells are of opposite mating type, and the "male" requires a sex pilus to create a mating bridge for the transfer of DNA. The donor cell carries a plasmid (F factor, "F+"). When an F factor is a plasmid, it is transferred to a F- cell via a pilus and the recipient is converted to an F+ cell. However, when an F factor becomes integrated into the actual chromosome of an F+ cell, it becomes a high frequency recombination (HFR) cell. When an HFR donor passes a portion of its chromosome into an F- recipient cell, a recombinant F- cell results.

What is meant by DNA fingerprinting?

DNA fingerprinting is the electrophoresis of restriction enzyme digests of an organism's DNA (in other words, it tests DNA, it's NOT testing a fingerprint...). This test compares fragments of DNA from different organisms to provide information on genetic similarities and differences. This test is useful for understanding DNA, sequencing genomes, and identification by DNA.

What does a ligase do? What kind of bonds does it form?

DNA ligase links Okazaki fragments together with covalent bonds.

What do you need for DNA replication?

DNA polymerase

What is a primer? What enzyme needs one to start working? What enzyme does not need one? What enzyme makes the primer for DNA synthesis?

DNA polymerase III needs a primer to make a 3' hydroxyl so that the DNA polymerase can add a 5' phosphate. DNA primase (or, RNA polymerase) makes the primer for DNA synthesis. RNA polymerase does not need a primer.

What is the name of the enzyme that copies DNA and synthesizes new DNA? That reads DNA and synthesizes RNA?

DNA polymerase; RNA polymerase

What advantage does a dimorphic fungus have?

Dimorphic fungi have two shapes, so they can exist as a yeast OR a mold. They can be temperature dependent, or it could have something to do with other environmental factors, such as food availability, oxygen, etc....

What are enterics?

Enterics are enterobacterial gammaproteobacteria. *E. coli* and *Salmonella* are some examples. This class of bacteria often inhabit the intestinal tracts of humans and animals.

What do we know about the three-domain system?

Evolutionary (phylogenic) relationships are determined by examining the sequence of nucleotides in 16s rRNA in prokaryotes and 18s rRNA in eukaryotes. The use of rRNA is because it's in all living cells, it has a similar function in all living cells, and it is well conserved.

Following conjugation of a F+ and F- cell, does the F- cell become a F+ cell or does it stay a F- cell? Explain.

Following conjugation, the plasmid is replicated and transferred to the F- cell. Since the F factor (F+) IS a plasmid, the F- cell becomes an F+ cell.

Are fungi prokaryotic cells or eukaryotic cells? Haploid or diploid?

Fungi are *eukaryotic* cells. They are *haploid* when they sexually reproduce and form gametes by meiosis, but they are *diploid* when the haploid gametes come together. They are also diploid in the instance they asexually reproduce, such as budding, fission, and mitosis.

Why are fungi important to us? List several reasons.

Fungi are important because they give us bread, wine, and natural antibiotics. They also can cause diseases.

What is an organism's genotype? Its phenotype?

Genotype: the genes of an organism Phenotype: expression of the genes

How would you sterilize each of the following? Glassware, a heat sensitive vitamin solution, an old book, latex gloves, dental instruments.

Glassware: moist heat autoclave Heat Sensitive Vitamin Solution: filtration Old Book: Ethylene Oxide gas Latex Gloves: Radiation Dental Instruments: Radiation

How does an inducible operon differ from a repressible operon? What is catabolite repression?

Inducible operon: an operon that is turned OFF until a inducer binds to a repressor protein on an operator and turns it on. Repressible operon: an operon that is turned ON until a corepressor actives (by binding to) a repressor that turns off the operon. Catabolite repression: pertains to the glucose effect and the lac operon. GLUCOSE WINS! If the glucose concentration is high, ATP is high. That means no cAMP, so no expression of the lac operon.

Why is iodine such a good disinfectant? How does it do what it does?

Iodine penetrates the cell walls of an organism and disrupts the protein and nucleic acid structure and synthesis.

What is the significance of genetic recombination?

It gives bacteria a means of obtaining genetic diversity in its population, and sometimes can provide an advantage to the next generation.

What is conjugation in protozoans?

It is a means of sexual reproduction. It's when two cells fuse, a haploid nucleus (micronucleus) from each cell migrates to the other cell, the haploids fuse, the parent cells separate, each now a fertilized cell. When cells later divide, they produce daughter cells with recombinant DNA.

Life cycle of malaria:

Malaria sexually reproduces in a mosquito. A mosquito injects a *sporozoite* into its bite, and the sporozoite undergoes schizogony in the liver, and *merozoites* are produced. Merozoites infect red blood cells, forming a *ring stage* inside the cell. Red blood cells rupture, and merozoites infect new red blood cells. When a mosquito bites an infected human, it ingests *gametocystes*. In the mosquito's gut, the gametocytes unite to form a *zygote*. Resulting sporozoites migrate to the salivary gland of the mosquito, bites human, and it starts again.

What is a cladogram?

Maps that show evolutionary relationships among organisms based on rRNA sequences.

What is a biofilm?

Microbes seldom live as single-species colonies, so they form live communities called "biofilms", which are 3-dimentional structures made mostly of polysaccharides and some proteins and DNA. Biofilms provide an advantage to microbes by giving means of cell-cell communication (quorum sensing), the sharing of nutrients, and providing additional protection to the environment (creates 1000X resistance to microbicides).

What is unusual about mycoplasma?

Mycoplasmatales do not have a cell wall, and therefore are pleomorphic. They are very very tiny and pathogenic. M.pneumoniae (AKA "walking pneumonia") attach to eukaryotic cells and infect them while stealing the sterols from their host because they cannot make it themselves, so they HAVE to grow on blood products. They reproduce by fragmentation of filaments.

Why do cells need Nitrogen? Phosphate? Carbon? Sulfur?

Nitrogen: nucleic acids (DNA, RNA), ATP, amino acids, and *proteins* Phosphate: *DNA*, RNA, ATP, phospholipids Carbon: *everything*!!! Structural organic molecules, an energy source Sulfur: *amino acids* (cysteine, methionine), and vitamins (thiamine, biotin)

What is nucleic acid hybridization? What new techniques are based on this?

Nucleic acid hybridization measures the ability of DNA strands from one organism to hybridize with DNA strands of another organism. So, the greater degree of hybridization, the greater degree of relatedness. Methods of using a DNA probe to identify bacteria and the manufacturing of DNA chips are based on nucleic acid hybridization. Examples of DNA chips includes ribotyping (rRNA sequencing), and FISH (Fluorescent in situ hybridization).

How do we identify bacteria?

One can identify bacteria by matching "unknown" organism characteristics to known organisms. Identification can be determined by morphological characteristics of the microbe, differential staining (gram-staining, acid-fast staining, etc.), and biochemical tests to determine the presence of particular bacterial enzymes.

Outline the steps of binary fission.

One cell dividing into two cells: 1. Elongation of cell and DNA duplication 2. Cell wall & plasma membrane increase and start folding inward 3. Formation of cross wall between DNA regions 4. Cells separate into two new identical cells

Why does oxygen kill obligate anaerobes? Why doesn't it kill obligate aerobes?

Oxygen kills obligate anaerobes because they lack the enzymes to neutralize harmful forms of Oxygen (thus creating their Oxygen intolerance), but it doesn't kill obligate aerobes because superoxide dismutase enzyme allows them to neutralize toxic forms of Oxygen.

Know chemicals used in control of bacteria

Phenols, Iodine, Chlorine, Ethanol, Isopropanol, heavy metals Silver, Mercury, and Copper, preservatives Sorbic acid, Benzoic acid, Nitrites, and Calcium propionate, Aldehydes, gaseous sterilant Ethylene Oxide, and peroxygens such as Ozone (O3), Hydrogen Peroxide, and Benzoyl Peroxide.

How do phenols disinfect? Alcohols? The soaps? Halogens?

Phenols: disrupt plasma membranes, can remain active for extended periods of time. Lysol is an example. Alcohols: ethanol and isopropanol, denature proteins, disrupt membranes, and dissolve lipids. Soaps: degerming Halogens: Iodine alters protein synthesis and membranes, Chlorine is an oxidizing agent found in bleach and gas used in swimming pools.

Why can a bacterium live without a plasmid?

Plasmids carry non-essential genes. Sometimes, they might not even have a function!

Is radiation bactericidal or bacteriostatic? What do ionizing and nonionizing radiation do to cells?

Radiation is bactericidal, and is used as a means of sterilization. *Ionizing radiation* (X rays, gamma rays, electron beams) ionizes water to release hydroxide and damages DNA. *Nonionizing radiation* (UV) also damages DNA, and is used to kill airborne microbes in labs and hospitals.

What's a halophile?

Salt-loving organism. Often a characteristic of Staphlococci on skin.

What is meant by selection?

Selection is the process by which one tries to determine if a mutation occurred in an organism. Positive selection detects mutant cells because they grow (when they couldn't before) or appear different. Negative selection is when one detects mutant cells because they DON'T grow.

Why is Staphylococcus a problem? How is staphylococcus adapted to the skin?

Staph is a problem because is causes many skin infections and serious infections as well as nosocomial infections(from hospitals). Staph is well adapted to skin because they can grow under high salt concentrations, and there is a lot of salt on our skin and in our nasal passages.

An example of a bacterial genus with high GC ratio is:

Streptomyces

What is unusual about the streptomyces?

Streptomyces is a Gram positive Actinobacteria. It's an unusual bacteria because it has filaments and conidiospores in coils attached to the filament tips (which is VERY similar to fungi). Their colonies are known to make architectural designs.

What does superoxide dismutase do? Does a facultative anaerobe have this enzyme?

Superoxide Dismutase is an enzyme in a microbe that allows toxic forms of oxygen to be neutralized. Facultative anaerobes have this enzyme, that's why they are able to grow in the presence of Oxygen. (In fact, they grow faster in the presence of Oxygen)

What is the life cycle of Chlamydia?

The "elementary body" attaches to a host cell, the host cell engulfs the elementary body into a vacuole, the elementary body reorganizes to form a "reticulate body", the reticulate body divides into more reticulate bodies, the reticulate bodies begin to convert BACK to elementary bodies, and the elementary bodies are released from the host cell.

Gram-positive bacteria are sorted based on?

The GC ratios in the bacteria's DNA. *Firmicutes* have LOW GC ratios, while *Actinobacteria* have HIGH GC ratios.

How is the repressor of the lac operon inactivated? (Understand the lac operon)

The Lac Operon (genetic info for metabolizing lactose) is an *inducible* operon, meaning that it is turned off by an active repressor protein until lactose (the inducer) is present in the cell. Then, the repressor protein will be inactivated and those genes can undergo protein synthesis.

How are bacteria categorized in the phylum Proteobacteria? Phylogenetically or morphologically?

The five phylums of proteobacteria are: 1. *Alphaproteobacteria* (α): capable of growing with few nutrients. ---Human pathogenic genuses Bartonella(cat-scratch), Ehrlichia(tick bourne), *Rickettsia*(rocky mountain spotted fever) ---Plant pathogenic genuses *Rhizobium*(fix N in plant roots), Agrobacteria(create tumors in plant cells) 2. *Betaproteobacteria* (β): use H gas, NH3, and methane as nutrients. ---Bordatella(whooping cough), Neisseria(gonorrhea and meningitis) 3. *Gammaproteobacteria* (ɣ): ---*Francisella*: pleomorphic rod, F.tularensis(rabbit fever) ---*Pseudomonales*: opportunistic pathogens, often resistant. Causes pneumonia, UTI's, conjunctivitis (Moraxella) ---*Legionellales*: found in streams, warm water. ---*Vibrionales*: found in coastal water ---*Enterobacteriales*: peritrichous flagella, faculative anaerobes, found in intestines. Escherichia(*E.coli*), *Salmonella*, Serratia, Shigella 4. *Deltaproteobacteria* (δ): pathogenic to OTHER bacteria! *Bdellovibrio* prey on other bacteria. 5. *Epsilonproteobacteria* (ε): slender, helical bacteria.

Describe the structure of a filamentous fungus. (hyphae, mycelium)

The fungal body, thallus, consists of *hyphae*, and a mass of hyphae is a *mycelium*. Hyphae are classified based on presence or absence of crosswalls separating nuclei. *Septate hyphae* divides the hyphae into uninucleate units, forms chains of distinct cells, and uses pores to allow the movement of cytoplasm between hyphae. *Coenocytic* or *Non-Septate hyphae* do not have complete crosswalls.

During DNA replication, how does the 'leading strand' differ from the 'lagging' strand?

The leading strand is synthesized continuously while the lagging strand is synthesized discontinuously (Okazaki fragments)

How do we measure microbial growth?

There are two ways, one is to measure cells directly. This can be done by viewing dead and alive cells under a microscope, or plating cells on agar plates to view viable cells and use serial dilutions to determine cell count. There are also indirect methods, like measuring the turbidity, metabolic activity, or dry weight of a culture.

What is a thermophile? A mesophile? A psychrophile?

Thermophiles: heat loving ---Optimum: 55 - 75 °C ---EXTREME Thermophiles: 65 - 110 °C Mesophiles: moderate temperature loving ---Optimum: 28 - 45 °C Psychrophiles: cold loving --- 0 - 15 °C

What does ultraviolet light do to DNA? Does it affect RNA?

UV light will form dimers on the same strand of a DNA, and is in need of repair. RNA can be affected, but will usually be degraded by the cell.

You have just isolated a chemical from the roots of a bayberry bush. What would you do to determine if the chemical is bacteriostatic or bactericidal?

Use the *disk-diffusion* method to evaluate the disinfectant

Following conjugation of a Hfr cell and a F- cell, does the F- cell become a F+ cell or a Hfr cell? Explain.

When an HFR donor mates with a F- cell, the HFR cell only donates a portion of its DNA, since the F factor is incorporated into it's legitimate genome (and NOT on an individual plasmid). Since the HFR cell only passes a portion of its chromosome into an F- recipient, it remains F-, but is also recombinant. Therefore, the result is the F- cell doesn't become F+ or HFR.

Know the growth characteristics of yeast. What is a yeast? What are two ways yeast replicate? Know the steps

Yeast is a unicellular, nonfilamentous, spherical OR oval fungus. They can form colonies, and can replicate asexually by budding or by fission. *Budding* takes place when a parent yeast forms a bud, and the bud elongates until the parent cell nucleus divides. Then, one nucleus goes into the bud, the bud enlarges, a cell wall is synthesized, and the bud breaks off! *Fission* yeast divide symmetrically. The parent yeast elongates, the nucleus divides, then the two cells break apart.

Are members of the genus Pseudomonas proteobacter? Other than morphology, what are two facts about the pseudomonads?

Yes, Pseudomonas ARE proteobacteria(gamma). Pseudomonas are metabolically diverse opportunistic pathogens with polar flagella, often resistant to many antibiotics and disinfectants.

What do you need for transcription? What does the sigma factor do?

You need RNA polymerase for transcription. Sigma factors recognize the promoter sequence.

Sterilization definition

a process in which *all* forms of microbial life are destroyed. This includes endospores and viruses, and sterilization has no degrees of sterility.

Disinfection definition

a process in which the vegetative microbial forms are destroyed. However, this does not necessarily include endospores or viruses. Disinfectants are usually chemicals used on inanimate objects.

What is an operon?

a segment of DNA where genes can be turned on and off depending on what the needs of cell are (or what the cell doesn't need)

Why is it that bacteria do not develop resistance to the chemical disinfectants or antiseptics?

chemical disinfectants and antiseptics are very non-specific in nature. Therefore, these methods would affect ANY protein, lipid, or membrane on any cell (assuming these cells are vegetative). Therefore, it would be quite difficult for a microbe to completely change the structure of their macromolecules to become resistant to disinfectants. Resistance typically arises when antibiotics, a more organism-specific method of killing microorganisms, kills all cells except those who are already resistant, causing the survivors to procreate.

Antiseptic definition

meaning "against infection". It's used for the chemical disinfection of living tissues, and is a disinfectant that does not destroy the living tissues.

Sepsis definition

microbial contamination

During repression, a repressor protein binds to the _________ region of an operon. This prevents __________.

operator, transcription

Why is pH important for growth? Why is osmotic pressure important for growth?

pH: buffers insure stabilization of pH in a solution. Osmotic Pressure: hypertonic environments (or an increase in salt or sugar) causes plasmolysis.

Asepsis definition

the absence of significant microbial contamination. Aseptic surgery technique prevents microbial contamination of wounds.

If a person is studying "genomics" what is he/she studying?

the molecular study of genetic information in a cell, through mapping, sequencing, and analysis.