Classification of Microbes (Lec. 9)

Question 1

Use the binomial nomenclature system

Answer 1

Genus species, all italicized, Genus capitalized

Question 2

Summarize the taxonomic hierarchy from domain to species

Answer 2

Domain, Kingdom, Phylum, Class, Order, Family, Genus, species

Question 3

Define taxonomy

Answer 3

the branch of science concerned with classification of organisms

Question 4

Define taxon

Answer 4

a taxonomic group of any rank, such as a species, family, or class

Question 5

Define phylogeny

Answer 5

the study of the evolutionary history of organisms

Question 6

Define culture

Answer 6

the growth of microorganisms in a lab under specific conditions

Question 7

Define clone

Answer 7

a cell, tissue, or organism that is an exact genetic replica of another cell, tissue, or organism

Question 8

Define strain

Answer 8

a genetic variant, subtype, or culture within a biological species.

Question 9

Define protist

Answer 9

a single-celled organism of the kingdom Protista in the domain Eukarya

Question 10

List the characteristics of the Bacteria domain

Answer 10

Prokaryotic; cell wall contains peptidoglycan; membrane lipids are composed of straight carbon chains attached to glycerol by ester linkage; first amino acid in protein synthesis is Formylmethionine; susceptible to antibiotics; has an rRNA loop and a common arm of tRNA; reproduce through binary fission

Question 11

List the characteristics of the Archaea domain

Answer 11

Prokaryotic; cell wall varies in composition but contains no peptidoglycan; membrane lipids are composed of branched carbon chains attached to glycerol by ether linkage; first amino acid in protein synthesis is methionine; resistant to antibiotics; does not have an rRNA loop or a common arm of tRNA; reproduce through binary fission

Question 12

List the characteristics of the Eukarya domain

Answer 12

Eukaryotic; cell wall varies in composition but contains carbohydrates; membrane lipids are composed of straight carbon chains attached to glycerol by ester linkages; first amino acid in protein synthesis is methionine; no rRNA loop but does have a common arm of tRNA; reproduce sexually or asexually

Question 13

Differentiate between identification and classification

Answer 13

Identification is matching characteristics of an unknown organism to lists of known organisms. Classification is placing organisms in groups of related species

Question 14

Describe how a newly discovered microbe can be classified by DNA sequencing

Answer 14

DNA sequencing determines the precise order of nucleotides, and the resulting sequence can be compared to known microbial DNA sequences to identify the organism’s closest relatives.

Question 15

Describe how a newly discovered microbe can be classified by DNA fingerprinting

Answer 15

DNA fingerprinting focuses on confirmation of the identity of individual organisms, and compares the DNA of the organism to known species

Question 16

Describe how a newly discovered microbe can be classified by NAAT

Answer 16

Nucleic acid amplification tests like PCR can create many copies of a small sample of DNA, and therefore make it easier to study and classify.

Question 17

Describe how microorganisms can be identified by nucleic acid hybridization

Answer 17

There are many different methods of nucleic acid hybridization, but they all involve exposing a DNA sample to a DNA probe with a tag, which can find and label any DNA sequences complementary to its DNA.

Question 18

Describe how microorganisms can be identified by Southern blotting

Answer 18

Southern blotting is a type of nucleic acid hybridization in which DNA fragments are separated by size by gel electrophoresis, then transferred to a membrane, then exposed to a labeled DNA probe with a radioactive, fluorescent, or chemical tag.

Question 19

Describe how microorganisms can be identified by DNA microarrays

Answer 19

DNA microarrays are a type of nucleic acid hybridization in which a chip with specific complementary DNA sequences is mixed with a DNA sample that has been fluorescently dyed. A machine is used to measure the intensity of the fluorescence at each sequence on the chip.

Question 20

Describe how microorganisms can be identified by ribotyping

Answer 20

Ribotyping specifically looks at the rRNA genes, through gel electrophoresis and analysis of the banding pattern. Useful when figuring out domain or phylum; but less useful for anything more specific.

Question 21

Explain serology in terms of classifying and identifying microorganisms

Answer 21

Serology is the study of what is in a patient’s serum; can determine through immunological methods (lab techniques involving the interaction of antigens with specific antibodies) if a patient has certain antigens or antibodies in their blood. Useful for bacteria, few fungi, protozoa (very rare), and viruses

Question 22

Differentiate a dichotomous key from a cladogram

Answer 22

A dichotomous key is an identification key based on successive questions; each question has two possible answers. A cladogram is a map that shows evolutionary relationships among organisms (based on rRNA sequences).