BIOL 2041-MODULE 8

What is a species (eukaryotes)?

A group of organisms that can interbreed and produce fertile offspring.

Why is the species concept different in prokaryotes?

Prokaryotes reproduce asexually, so the ability to interbreed cannot be used to define a species.

What is a strain?

A genetic variant or subtype within a species.

What is a genus?

A taxonomic rank above species that groups closely related species.

What is binomial nomenclature?

The two-part scientific naming system consisting of a genus and species.

Who developed binomial nomenclature?

Carl Linnaeus.

How are scientific names formatted?

The genus is capitalized, the species is lowercase, and both are italicized (or underlined if handwritten).

Example of a correctly formatted scientific name.

Escherichia coli

Who makes a scientific name official?

The appropriate international nomenclature committee.

What are the taxonomic levels from largest to smallest?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

What is morphology?

The study of an organism's physical shape and structure.

Give an example of a morphological characteristic used in classification.

Cell shape (coccus, bacillus, spirillum), colony appearance, or cell arrangement.

What is differential staining?

A staining technique used to distinguish microorganisms based on structural differences.

Give an example of a differential stain.

Gram stain.

What are biochemical tests?

Tests that identify microorganisms based on their metabolic or enzymatic activities.

Give an example of a biochemical test.

Catalase test, oxidase test, or carbohydrate fermentation.

What is serology?

The identification of microorganisms using antigen-antibody reactions.

What is an example of a serological test?

ELISA or agglutination tests.

What are phylogenetic classification systems based on?

Evolutionary relationships and genetic similarity.

What is a molecular chronometer?

A molecule that changes slowly over time and is used to determine evolutionary relationships.

What molecule is commonly used as a molecular chronometer in bacteria?

16S rRNA.

What is a phylogenetic tree?

A branching diagram that shows the evolutionary relationships among organisms.

What do the branch points (nodes) on a phylogenetic tree represent?

A common ancestor.

What do organisms that are closer together on a phylogenetic tree have in common?

They are more closely related evolutionarily.

True or False: Organisms in the same genus are more closely related than organisms in the same family.

True.

True or False: Scientific names consist of three words.

False.

True or False: The genus name is capitalized.

True.

True or False: The species name is capitalized.

False.

True or False: Both the genus and species names are italicized.

True.

True or False: Morphology alone is always sufficient to identify a microorganism.

False.

True or False: Phylogenetic classification is based on evolutionary relationships.

True.