Microbiology Quiz on Pathogens and Techniques

Sulfonamides inhibit the synthesis of folic acid, a crucial nutrient for bacteria, by blocking the enzyme dihydropteroate synthetase (DHPS). This enzyme is responsible for converting para-aminobenzoic acid (PABA) into dihydrofolic acid, an essential precursor to tetrahydrofolic acid (THF). Sulfonamides resemble PABA and competitively bind to DHPS, preventing the synthesis of dihydrofolic acid and ultimately blocking the production of THF.

Vibrio cholerae produces yellow colonies on TCBS agar due to its ability to ferment sucrose, producing acidic byproducts that turn the pH indicator in the medium yellow. This color change allows for easy identification of V. cholerae from other bacteria.

The M2 protein in Influenza A facilitates the uncoating of the virus inside the host cell. This is achieved by acidifying the interior of the viral particle, causing the viral envelope to dismantle and release the viral genome into the host cell cytoplasm.

Bacterial vaginosis (BV) is characterized by the presence of clue cells, which are vaginal epithelial cells coated with a heavy layer of bacteria. This bacterial overgrowth disrupts the normal vaginal flora and can lead to BV symptoms like an abnormal vaginal discharge and odor. The presence of clue cells is a key feature of BV and can be identified under a microscope.

Neuraminidase (NA) plays a critical role in the release of new viral particles (progeny virions) from the host cell in Influenza A infections. NA cleaves sialic acid residues, which are sugars that anchor the virus to the host cell surface. By removing these attachments, NA allows the newly formed virions to detach and spread to infect other cells.

Enrichment media are specifically designed to encourage the growth of certain microorganisms while inhibiting the growth of others. They provide specific nutrients and environmental conditions that favor the desired organisms, making them easier to isolate and identify. For example, selenite broth is an enrichment medium for Salmonella species.

HIV reverse transcriptase is an enzyme that converts the viral RNA genome into DNA. This process, called reverse transcription, is unique to retroviruses and allows HIV to integrate its genetic material into the host cell's genome. Once integrated, the viral DNA can be used to produce new viral particles.

The A subunit of Vibrio cholerae's AB toxin is responsible for activating a host cell's Gs protein. This activation leads to an increase in cyclic adenosine monophosphate (cAMP) levels, resulting in the disruption of normal ion transport across the intestinal lining. This disruption causes excessive water and electrolyte loss, leading to the characteristic watery diarrhea seen in cholera.