40 Questions
What is the primary function of a microscope in microbiology?
To observe microorganisms that are too small to be seen by the naked eye
Who is credited with being the first to observe microorganisms using a simple microscope?
Antonie van Leeuwenhoek
What is the theory that states living things can arise from vital forces present in nonliving and decaying matter?
Spontaneous Generation
Who is credited with developing aseptic techniques and a rabies vaccine?
Louis Pasteur
What is the process by which sugar is converted to alcohol to make beer and wine?
Fermentation
What is the result of bacterial growth on wine?
Spoilage of wine to vinegar
What is the purpose of heat in Pasteur's method of preserving wine?
To kill spoilage bacteria
What is the term for the theory that living organisms can arise only from preexisting life forms?
Biogenesis
What is the primary goal of phylogeny or systematics?
To identify all organisms by 2025
Which of the following is NOT a characteristic of the kingdom Plantae?
Ingestive
What is phage typing used for?
Determining the susceptibility of bacteria to phages
Which domain includes organisms with unusual cell walls and membranes?
Archaea
What is the primary focus of chemotaxonomy?
The study of the chemical variation in microbial cells
What is the primary function of differential staining techniques in identifying bacteria?
To determine the morphological characteristics of bacteria
What is the significance of peptidoglycan in bacterial classification?
It provides important information for the classification of bacteria
What is the primary function of biochemical tests in identifying bacteria?
To identify the presence of bacterial enzymes
What is the significance of DNA fingerprinting in microbiology?
It is used to analyze the restriction enzyme digests of DNA
What is the term for the study of evolutionary relationships and history among organisms?
Phylogeny
What is the function of the International Code for the Nomenclature of Bacteria?
To establish a universal system for naming bacteria
What is the purpose of using dichotomous keys in identifying organisms?
To identify the specific species of an organism
What is the primary characteristic used to identify the species of a bacterium?
Physiological characteristics
What is the purpose of analyzing the fatty acid composition of bacterial membranes?
To identify the chemical characteristics of bacteria
What is the purpose of analyzing the end products of bacterial metabolism?
To identify the physiological characteristics of bacteria
What is the purpose of analyzing the structure of cell wall murein in bacteria?
To identify the chemical characteristics of bacteria
What is the primary application of numerical taxonomy?
To carry out taxonomic work with less skilled workers
What is the function of the Ribosomal Database Project (RDP)?
To maintain a large collection of rRNA sequences and provide analytical programs
What is the significance of 16S rRNA gene sequences in taxonomy?
They serve as a 'gold standard' for the identification and description of new species
What is the significance of Carl Woese's work?
He established the presence of three domains of life: Bacteria, Archaea, and Eukarya
What is the characteristic of the 16S rRNA gene sequences used for phylogenetic studies?
They are functionally constant and change slowly
What is the proposed threshold for considering a bacterium as a new species?
A difference of 3% in 16S rRNA gene sequence from any named strain
What is the purpose of whole-genome sequence analyses?
To study the genome structure and composition
What is the significance of the Domain Bacteria?
It contains at least 80 major evolutionary groups (phyla)
Which of the following sugars is not typically associated with whole cell hydrolysate?
Galactose
What is the primary function of respiratory quinones in the bacterial cytoplasmic membrane?
Electron transport chain
What is the typical carbon atom range found in fatty acids of bacterial membranes?
8-20
Which type of lipid is NOT typically associated with bacterial plasma membranes?
Sterols
What is the primary characteristic of amphipathic polar lipids in bacterial plasma membranes?
Hydrophilic head groups linked to two hydrophobic fatty acid chains
What is the significance of analyzing the quinone system in bacterial characterization?
It provides insight into the bacteria's chemotaxonomic properties
Which of the following is a type of phosphatidylglycolipid?
Diphosphatidyglycerol
Which of the following sugars is typically associated with whole cell hydrolysate?
Ribose
Study Notes
Introduction to Microbiology
- Microbiology: the study of organisms too small to be seen by the naked eye, requiring a microscope
- Microbes or microorganisms: commonly referred to as “germs” or “bugs”, include bacteria, helminths, fungi, algae, protozoa, and prions (infectious proteins)
History of Microbiology
- Antonie van Leeuwenhoek: first observed microbes using a simple microscope (1673) and reported his “animalcules” to the Royal Society of London
- Francesco Redi: opposed the theory of Spontaneous Generation, showing that maggots came from flies (1668)
- Biogenesis: the theory that life comes from life, opposed to Spontaneous Generation
The Golden Age of Microbiology
- Louis Pasteur (1822-1895): showed microbes caused fermentation and spoilage, disproved spontaneous generation, developed aseptic techniques, and developed a rabies vaccine
- Fermentation and Pasteurization:
- Microbes responsible for fermentation
- Fermentation: conversion of sugar to alcohol to make beer and wine
- Microbial growth responsible for spoilage of food
- Bacteria that use alcohol and produce acetic acid spoil wine by turning it to vinegar
Bacterial Taxonomy
- Physiological characteristics:
- Respiratory chain enzymes (oxidases, catalases)
- Enzymes that break down carbohydrates, alcohols, glycosides (e.g., betagalactosidase)
- Protein metabolism enzymes (e.g., gelatinase, collagenase)
- Amino acid metabolism enzymes (e.g., decarboxylases, deaminases, urease)
- Chemical characteristics:
- DNA structure (base sequences)
- Structure of cell wall murein
- Antigen structure: fine structures detectable with antibodies
- Fatty acids in membranes and cell wall
Identifying Bacteria
- Morphological characteristics: useful for identifying eukaryotes
- Differential staining: Gram Staining, acid-fast staining
- Biochemical tests: determines presence of bacterial enzymes
- Dichotomous keys used for identification of organisms
Nomenclature
- International Code for the Nomenclature of Bacteria: sets out rules for bacterial nomenclature
- Species designated with two Latinized names, the first characterizing the genus and the second the species
- Family names always end in -aceae
Phylogeny or Systematics
- Shows evolutionary relationships and history among organisms
- Some obtained from fossil record, most bacteria use rRNA sequencing or some other sequence information
- Goal is to identify all organisms by 2025
Phage Typing
- Determines susceptibility to certain phage or bacterial viruses
Genetics
- DNA base composition: Guanine + cytosine moles% (GC)
- DNA fingerprinting
- Electrophoresis of restriction enzyme Digests
- rRNA sequencing
- Polymerase Chain Reaction (PCR)
The 3 Domains
- Eukarya: plants, animals, fungi, and protists
- Bacteria (with peptidoglycan)
- Archaea: with unusual cell walls and membranes
Chemotaxonomy
- Study of the chemical variation in microbial cells and the use of chemical characteristics in the classification and identification of bacteria
- Examines the distribution of chemical macromolecules containing amino acids, peptides, lipids, polysaccharides, and other related polymers, proteins, enzymes, and other complex polymeric molecules
- Characters used in bacterial chemotaxonomy:
- Peptidoglycan
- Diamino acids
- Polysaccharides
- Teichoic acids
- Mycolic acids
- Fatty acids
- Polar acids
- Isoprenoid quinones
- Polyamines
- Prokaryotic pigments
- LPS
Phylogeny
- Evolutionary history of a group of organisms
- Inferred indirectly from nucleotide sequence data
- Molecular clocks: small subunit ribosomal RNA (SSU rRNA) genes
- 16S rRNA in prokaryotes and 18S rRNA in eukaryotes
Bacterial Phylogeny
- Domain Bacteria: contains at least 80 major evolutionary groups (phyla)
- Many groups are phenotypically diverse, i.e., physiology and phylogeny not necessarily linked
This quiz covers the basics of microbiology, including the definition, importance, and types of microorganisms, as well as the history of microbiology and the first microscope.
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