38 Questions
What is the basis of genotypic classification of bacteria?
DNA-DNA hybridization and G+C content
What is the main purpose of 16S rRNA sequences in classifying prokaryotes?
To analyze the nucleotide sequence differences
Which of the following is a characteristic of Gram-positive bacteria?
They have a thick peptidoglycan layer
What is the primary function of genetic probes in DNA analysis?
To identify specific DNA sequences
Which group of bacteria includes methanogens and extreme thermophiles?
Archaea
What is the primary basis of phenotypic classification of bacteria?
All of the above
What is the main advantage of using rRNA sequence analysis in classifying prokaryotes?
It provides evolutionary context and makes biological sense
What is the primary characteristic of halophiles?
They thrive in high-salt environments
What is a characteristic of Archaea that distinguishes them from bacteria?
Having unique genetic sequences in their rRNA
Which of the following is NOT a characteristic of Eukaryotes?
Lacking membrane lipids
What is the name of the kingdom that includes protozoa in the Whittaker classification?
Kingdom Protista
What is a characteristic of protozoa?
Lacking photosynthetic capability
Which of the following is an example of an extreme environment that Archaea can thrive in?
High-temperature hot springs
What is the term for organisms that are adapted to live in extreme environments?
Extremophiles
What is the key characteristic of heterotrophic organisms like fungi?
Cannot produce their own food
What is the primary source of energy and carbon for fungi?
Organic compounds
What is the common characteristic of the cells of fungi?
Usually organized into branched, multinucleate filaments
What is the term for the network of tubes that make up mushrooms?
Hypae
How many species of fungi are estimated to exist?
100,000
What is the characteristic of yeast fungi?
Unicellular
What is the primary basis for fungal classification?
Spore-forming structures and sexual spores
What is the term for the filaments that make up mycelia?
Hyphae
What is the primary method used to quantify viruses?
Counting the number of plaques
What is the study of viruses called?
Virology
What are the two main components of a virus?
Nucleic acid and capsid
What is unique about retroviruses?
They have a single-stranded RNA genome
What is the primary function of the capsid?
To protect the viral genome
What is the classification of viruses based on?
Multiple parameters including the type of genomic nucleic acid, size of the virion and genome, and more
What is a characteristic of viroids?
They are infectious pieces of naked RNA
What is a characteristic of prions?
They are infectious proteins
What is the name of the domain that includes humans, animals, and plants?
Eukarya
What does the prefix 'pro' mean in the term 'prokaryotes'?
Before
What is the level of classification that is used to identify each creature in binomial nomenclature?
Species
What is the term for the naming system used to identify microorganisms?
Binomial Nomenclature
What is the correct way to write the genus name in binomial nomenclature?
In uppercase letters
What is the characteristic that distinguishes eukaryotes from prokaryotes?
Presence of a nucleus
What is the order of classification in the taxonomic hierarchy?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
What is the abbreviation for the species Escherichia coli?
E.coli
Study Notes
Cell Classification
- Three domains: Bacteria, Archaea, and Eukarya
- Bacteria: prokaryotes, lack peptidoglycan, binary fission, energy from organic chemicals, inorganic chemicals, or photosynthesis
- Archaea: prokaryotes, lack peptidoglycan, live in extreme environments, include methanogens, extreme halophiles, and extreme thermophiles
- Eukarya: eukaryotic cells, have a nucleus, organelles, reproduce asexually or sexually, examples include protozoans, molds, plants, and animals
Taxonomic Hierarchy
- Domain: highest level of classification
- Kingdom: second level of classification
- Phylum: third level of classification
- Class: fourth level of classification
- Order: fifth level of classification
- Family: sixth level of classification
- Genus: seventh level of classification
- Species: eighth level of classification
Binomial Nomenclature
- Uses Genus and Species names to identify each creature
- Examples: Escherichia coli, Staphylococcus aureus, Bacillus subtilis
Microorganism Classification
- Phenotypic classification: based on shape, size, and staining
- Genotypic classification: based on DNA-DNA hybridization, G+C content, and rRNA sequence
Bacteria Shapes
- Three main shapes: Cocci, Bacilli, and Spiral
Cell Wall Composition
- Four groups: Gram-positive, Gram-negative, bacteria without cell walls, and bacteria with chemically unique cell walls
rRNA Sequence
- Used to classify prokaryotes
- 16S rRNA sequences and 23S rRNA sequences are used
Archaea
- Prokaryotes, lack peptidoglycan, live in extreme environments
- Include methanogens, extreme halophiles, and extreme thermophiles
Eukaryotes
- Eukaryotic cells, have a nucleus, organelles, reproduce asexually or sexually
- Examples include protozoans, molds, plants, and animals
Kingdom Protista
- Microscopic unicellular organisms, lack photosynthetic capability, usually motile, reproduce by asexual fission
- Examples include protozoans
Kingdom Fungi
- Heterotrophic, require organic compounds for energy and carbon source
- Cells are usually organized into branched, multinucleate filaments which absorb digested food from the external environment
- Examples include yeasts, molds, and mushrooms
Fungal Characteristics
- Chitin cell walls, use organic chemicals for energy, multicellular consisting of masses of mycelia, which are composed of filaments called hyphae
- Yeasts are unicellular
Viruses
- Acellular, obligate intracellular parasites, no ribosomes or means of protein synthesis, no ATP generating system
- Not alive
- Classified based on type of genomic nucleic acid, size of virion and genome, capsid structure, host, and replication mechanism
Virus Structure
- Two parts: nucleic acid (either DNA or RNA) and capsid (protein coat)
- Some capsids surrounded by envelopes
Viroids and Prions
- Viroids: infectious pieces of naked RNA, cause plant diseases, 300-400 nucleotides long, closed, folded 3D shape
- Prions: infectious proteins, cause diseases such as Mad cow and Creutzfeldt-Jakob
Learn about the differences between prokaryotes and eukaryotes and explore the three domains of life: Bacteria, Archaea, and Eukarya.
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