The viral DNA synthesis experiment determines when viral DNA synthesis begins. Infect cells, add 3H-thymidine. Remove aliquots every 2 minutes, hybridize to filters containing cold phage DNA. Determine when rise in viral DNA occurs. Handed DNA encoding ORF3 of Phage 1065. How would you determine whther the .8kb mRNA for ORF3 is amplified after viral [...]

Pseudomonads Optimal temperature of 30°C; strict aerobes, except in presence of nitrate or amino acids, and never fermentative; gram-negative; motile; non-sporulating; and cytochrome oxidase positive. No more than 3µm in size. Some species are capable of dissimilative nitrate reduction (denitrification) — assimilative nitrate reduction is for nitrogen as a general nutrient, instead of an energy [...]

There are two types of tissue cultures: primary cultures, derived directly from animal tissues; and transformed cell lines, which are engineered to reproduce indefinitely. Tissues cultures must be handled in biosafety hoods because they are innately considered biohazards (transformed cell lines are oncogenic), and are highly susceptible to the fungi which heavily populate breathing air. [...]

In binary fission, a parent cell divides to form two daughter cells. Thus, bacterial population increase exponentially. Note the table below, demonstrating how quickly a population of bacteria can explode from just a single cell. The generation (first, second, third, etc) is denoted n and the number of cells at a given time is N [...]

The Interrupted Mating Experiment basically uses the following steps: Cells are mixed, then shaken to break their pili and stop conjugation. Streptomycin is added to stop cell division. Cells gain certain traits depending on which genes have been transferred. By stopping conjugation at different times, gene order of a plasmid and its inserts can be [...]

The oxidase test assays for the presence of cytochrome c in a cell’s respiratory pathway. Cells are smeared onto a sheet coated with tetrametyl-p-phenylenediamine (TMP), a colorless electron donor. A functional cytochrome c removes electrons from TMP; this oxidized TMP has an intense purple-blue color. A positive control for the oxidase test is Pseudomonas fluorescens, [...]

An antibiotic is any chemical which inhibits microbial growth. Bleach is an antibiotic which completely sterilizes any surface it touches. However, there are other antibiotics which only affect certain cell types. These are useful for isolating bacteria, fungi and subtypes thereof. To test for antibiotic secretion, the microbe of interest is plated onto a lawn [...]

The polymerase chain reaction (PCR) replicates specific genetic sequences (DNA or RNA, in either plus- or minus-sense) so that vast quantities of a certain DNA segment can be quickly produced (amplification). PCR relies upon a few basic steps: Obtain genetic material for PCR. Add oligonucleotide primers complementary to the sequence you wish to amplify. Single [...]

Gram staining distinguishes cells based on bacterial cell walls. Gram-positive organisms have a thick cell wall and outer membranes that retains crystal violet, while Gram-negative cells have no inter-glycine bridge and thin cell walls which eventually are stained pink. There are several potential problems with Gram staining: old Gram-positive cultures may stain Gram-negative; Gram-negative smears [...]

Agarose gel (aka agar) is a very firm jelly that is laced with nutrients to grow colonies of microbes. A colony is a single cell which has reproduced to form a visible dot of cells. Note that fungal colonies are oftentimes fuzzy, while bacterial colonies are typically compact and gummy. Agar nomenclature is very simple. [...]

Auxotrophs are unable to synthesize all their own biomolecules (nutrients, such as amino acids). For example, a bio- mutant is unable to synthesize biotin. Auxotrophs can be studied to understand pathways for the synthesis of amino acids. Also, they can be used for other experiments (such as the Ames test and R-factor experiment). Isolating Auxotrophs [...]

Native to E. coli, the lac operon allows cells to use lactose (a sugar found in milk) for energy. Found only in prokaryotes, an operon is a contiguous row of genes transcribed from a single promoter. This means that genes within an operon are activated together and inactivated together. Most operons — including the lac [...]

Minimal media consists of merely a carbon source and trace elements (P, S, K, Mg, Ca, Na). Iron is used for cellular respiration. N2 is used for N-fixing bacteria. Growth factors needed n small amounts: vitamins, amino acids, purines and pyrimidines. Simple Media Contains precise amounts of highly purified organic and/or inorganic chemicals. For example, [...]

Colony Form Description Pinpoint Smaller than 1 mm. Circular A circle larger than 1 mm. Irregular A non-circular shape. Filamentous Resembling a bunch of strings. Colony Elevation Cushion Raised Flat Raised Center Colony Surface Smooth Smooth colony surface. Rough Rough colony surface. Ringed A colony surface with rings. Colony Texture Amorphous A typical textureless colony. [...]