Microbiology Flashcards
What is the microbial world?
A term coined by Professor Roger Stanier in 1966, referring to the world of microorganisms that coexist with higher life forms.
What are the three domains of life?
Prokaryotes (Bacteria), Eukaryotes, and Archaea.
What are the five main groups of microorganisms?
Algae, Protozoa, Bacteria, Fungi, and Viruses.
How are bacteria classified by shape?
Rod (bacilli), coccoid (cocci), and pleomorphic (variable shapes).
What is the difference between Gram-positive and Gram-negative bacteria?
Gram-positive have a thick peptidoglycan layer; Gram-negative have a thin layer and an outer LPS membrane (toxic to humans).
What is binary fission?
A bacterial reproduction method where a single cell divides into two identical daughter cells.
What are bacterial spores?
Dormant, highly resistant structures that allow bacteria to survive unfavorable conditions and spread via dust and air.
What are extremophiles?
Microorganisms, mainly archaea, that thrive in extreme environments like high salinity, high temperature, and acidity.
What is the function of fungi?
Fungi decompose organic matter and include yeasts and molds, which reproduce via spores.
What is the role of yeast in food production?
Yeasts ferment carbohydrates to produce ethanol and CO₂, used in bread, beer, and wine production.
What is the difference between bacterial spores and fungal spores?
Bacterial spores are for survival and highly resistant; fungal spores are for reproduction and dispersion.
What are viruses composed of?
Viruses consist of genetic material (DNA or RNA) enclosed in a protein coat, sometimes with a lipid membrane.
How do viruses reproduce?
Viruses require a host cell to replicate, as they lack cellular structures for independent reproduction.
What are the functions of microorganisms in food?
Microorganisms contribute to food production (fermentation), spoilage, and can cause disease.
What are the characteristics of prokaryotic cells?
No nucleus, no organelles, cell wall of peptidoglycan, binary fission, and usually one circular chromosome.
What are the characteristics of eukaryotic cells?
Have a nucleus, organelles, undergo mitosis, and have linear chromosomes.
What are examples of eukaryotic microorganisms?
Yeasts, microfungi, protozoa, and microalgae.
What are examples of food spoilage by microorganisms?
Yeasts and molds causing food degradation, bacterial contamination leading to spoilage.
How do molds grow?
They grow in moist places, require oxygen, and can break down both simple and complex nutrients.
What are mycotoxins?
Harmful chemicals produced by certain fungi that can cause health issues.
