Biology: Prokaryotes, Eukaryotes, and the Three Domains

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Questions and Answers

What is the basis of genotypic classification of bacteria?

Cultural characteristics and environmental factors

DNA-DNA hybridization and G+C content (correct)

Antigenic structure and nutrition

Morphological characteristics

What is the main purpose of 16S rRNA sequences in classifying prokaryotes?

To identify the shape of the bacterium

To analyze the nucleotide sequence differences (correct)

To detect the presence of peptidoglycan in the cell wall

To determine the G+C content of the DNA

Which of the following is a characteristic of Gram-positive bacteria?

They have a thick peptidoglycan layer (correct)

They are halophiles

They lack a cell wall

They have a thin peptidoglycan layer

What is the primary function of genetic probes in DNA analysis?

To identify specific DNA sequences Signup and view all the answers

Which group of bacteria includes methanogens and extreme thermophiles?

Archaea Signup and view all the answers

What is the primary basis of phenotypic classification of bacteria?

All of the above Signup and view all the answers

What is the main advantage of using rRNA sequence analysis in classifying prokaryotes?

It provides evolutionary context and makes biological sense Signup and view all the answers

What is the primary characteristic of halophiles?

They thrive in high-salt environments Signup and view all the answers

What is a characteristic of Archaea that distinguishes them from bacteria?

Having unique genetic sequences in their rRNA Signup and view all the answers

Which of the following is NOT a characteristic of Eukaryotes?

Lacking membrane lipids Signup and view all the answers

What is the name of the kingdom that includes protozoa in the Whittaker classification?

Kingdom Protista Signup and view all the answers

What is a characteristic of protozoa?

Lacking photosynthetic capability Signup and view all the answers

Which of the following is an example of an extreme environment that Archaea can thrive in?

High-temperature hot springs Signup and view all the answers

What is the term for organisms that are adapted to live in extreme environments?

Extremophiles Signup and view all the answers

What is the key characteristic of heterotrophic organisms like fungi?

Cannot produce their own food Signup and view all the answers

What is the primary source of energy and carbon for fungi?

Organic compounds Signup and view all the answers

What is the common characteristic of the cells of fungi?

Usually organized into branched, multinucleate filaments Signup and view all the answers

What is the term for the network of tubes that make up mushrooms?

Hypae Signup and view all the answers

How many species of fungi are estimated to exist?

100,000 Signup and view all the answers

What is the characteristic of yeast fungi?

Unicellular Signup and view all the answers

What is the primary basis for fungal classification?

Spore-forming structures and sexual spores Signup and view all the answers

What is the term for the filaments that make up mycelia?

Hyphae Signup and view all the answers

What is the primary method used to quantify viruses?

Counting the number of plaques Signup and view all the answers

What is the study of viruses called?

Virology Signup and view all the answers

What are the two main components of a virus?

Nucleic acid and capsid Signup and view all the answers

What is unique about retroviruses?

They have a single-stranded RNA genome Signup and view all the answers

What is the primary function of the capsid?

To protect the viral genome Signup and view all the answers

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 Signup and view all the answers

What is a characteristic of viroids?

They are infectious pieces of naked RNA Signup and view all the answers

What is a characteristic of prions?

They are infectious proteins Signup and view all the answers

What is the name of the domain that includes humans, animals, and plants?

Eukarya Signup and view all the answers

What does the prefix 'pro' mean in the term 'prokaryotes'?

Before Signup and view all the answers

What is the level of classification that is used to identify each creature in binomial nomenclature?

Species Signup and view all the answers

What is the term for the naming system used to identify microorganisms?

Binomial Nomenclature Signup and view all the answers

What is the correct way to write the genus name in binomial nomenclature?

In uppercase letters Signup and view all the answers

What is the characteristic that distinguishes eukaryotes from prokaryotes?

Presence of a nucleus Signup and view all the answers

What is the order of classification in the taxonomic hierarchy?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species Signup and view all the answers

What is the abbreviation for the species Escherichia coli?

E.coli Signup and view all the answers

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

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Description

Learn about the differences between prokaryotes and eukaryotes and explore the three domains of life: Bacteria, Archaea, and Eukarya.