lab practical #2

Metabolic tests

Tests that determine the presence or absence of specific enzymes in bacteria.

Dichotomous key

A tool used to identify unknown organisms based on their characteristics.

Amylase test

Tests for the presence of amylase, using starch agar and iodine, indicated by a clearing around growth.

Lipase test

Tests for the presence of lipase in Tributyrin agar, indicated by a clearing around growth.

Catalase test

Tests for catalase activity by adding hydrogen peroxide (H2O2) and observing for bubbles indicating oxygen production.

Oxidase test

Uses a test strip with a reagent; a purple spot within 20 seconds indicates the oxidation of the reagent.

Citrate test

Tests for citrate permease using citrate agar, with a color change from green to blue indicating a positive result.

Fermentation tests

Involves glucose, lactose, and sucrose broths to determine fermentation enzymes, indicated by color change and gas production.

Methyl Red–Voges-Proskauer (MR-VP) test

Determines fermentation products; red for MR indicates acid; pink/red for VP indicates acetoin presence.

H2S test

Indicates cysteine desulfurase presence; color change from yellow to black in SIM medium with Fe salts.

Indole test

Tests for tryptophanase using an oxalic acid strip; a color change from white to pink indicates a positive result.

Motility test

Evaluates the growth pattern in a stab line; fuzzy growth indicates motility.

Phenylalanine deaminase test

Uses phenylalanine agar; a color change from clear to green indicates the presence of phenylalanine deaminase.

Urease test

Uses urea agar; color change from orange/yellow to neon pink indicates alkaline conditions due to ammonia.

Yeasts

Eukaryotic fungi that reproduce by budding; some can cause infections in immunocompromised individuals.

Saccharomyces cerevisiae

A species of yeast used in labs; shows asexual reproduction by budding.

Candida albicans

A yeast known for causing infections; identified microscopically by budding and purple shoe print appearance.

Molds

Eukaryotic fungi that reproduce through asexual spores and can cause infections.

Sabouraud agar

Selective medium for molds, enriched with high sugar and low pH to inhibit bacterial growth.

Aspergillus

A mold that can cause aspergillosis; transmitted through air and requires avoidance of dusty environments.

Coccidioides

A mold responsible for valley fever; prevented by avoiding exposure in endemic areas.

Plasmodium slime molds

Eukaryotes, free-living decomposers, identified by yellow string-like structures.

Physarum polycephalum

The slime mold used in labs to study cytoplasmic streaming.

Cytoplasmic streaming

Movement of nutrients and oxygen within cells for efficient distribution.

Acellular infectious agents

Viruses that require a host to replicate and cause disease.

Epstein-Barr virus

Virus that causes infectious mononucleosis, primarily transmitted through saliva.

Leukocytes

White blood cells involved in the immune response, including lymphocytes, neutrophils, monocytes, eosinophils, and basophils.

Gel electrophoresis

Technique for separating DNA fragments by size.

Molecular weight ladder

A size standard used in gel electrophoresis to identify unknown DNA fragments.

PCR (Polymerase Chain Reaction)

Technique used to amplify a specific DNA sequence.

CRISPR-Cas system

Bacterial immune system used for gene editing by cutting DNA.

Epidemiology

Study of the occurrence and transmission of diseases in populations.

Five-second rule

Belief that food dropped on the floor is safe to eat if picked up within five seconds.

Antibiotic sensitivity test

Determines the susceptibility of bacteria to specific antibiotics using methods like the Kirby-Bauer test.