Bacterial Systematics

Question 1

What is included in taxonomy?

Answer 1

• Grouping (classification)
• Naming (nomenclature)
• Description

The classification of organisms into similar groups.

Question 2

What are the main differences between bacteria and archaea?

Answer 2

1. Bacterial cell walls have peptidoglycan archaeal cell walls do not.
2. Bacteria have one (rRNA); archaea have three. In this respect archaea are similar to eukaryotes.
3. Bacteria cannot live above 100 degrees Celsius; archaea can thrive in extreme temperatures.
4. Bacterial growth is inhibited by antibiotics; archaeal growth is not inhibited by antibiotics.

Question 3

What is an evolutionary chronometer? Which properties must such a molecule have?

Answer 3

An evolutionary chronometer is a nucleotide sequence (usually) that
can be used to measure the evolutionary separation of two organisms
• Universally distributed across the group chosen for study
• Functionally homologous in each organism studied
• Conserved regions for alignments of adequate length
• Must change (mutate) at ”sufficient” rate

Question 4

What is sequence alignment?

Answer 4

a way of arranging the sequences of DNA, RNA, or protein to identify regions of similarity that may be a consequence of functional, structural, or evolutionary relationships between the sequences.

Question 5

List the order of the hierarchy system, from domain to species.

Answer 5

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 6

How is “species” defined in microbiology?

Answer 6

A group of strains that among others have same biochemical properties and also essentially
differentiate from other species

a taxonomic category that defines a population of individuals that (1) is monophyletic (descended from a common ancestor), (2) is genomically coherent, (3) is phenotypically coherent, and (4) can be clearly differentiated from other species.

Question 7

What is the binomial system?

Answer 7

is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin or Greek grammatical forms

Question 8

What is Bergey’s manual?

Answer 8

is the main resource for determining the identity of prokaryotic organisms

Question 8

Describe PFGE (Pulsed-field gel electrophoresis)

Answer 8

The scientist takes bacterial cells from an agar plate.
The scientist mixes bacterial cells with melted agarose and pours into a plug mold.
The bacterial cells are broken open with biochemicals, or lysed, so that the DNA is free in the agarose plugs.
The scientist loads the DNA gelatin plug into a gel, and places it in an electric ­field that separates DNA fragments according to their size.
The gel is stained, so that DNA can be seen under ultraviolet (UV) light. A digital camera takes a photograph of the gel and stores the picture in the computer.