Lecture 3 Flashcards
What is a Biotype?
Subspecies of bacteria defined by their biological characteristics
What are the hierarchies in bacterial taxonomic classification
Domain Division Class Family Genus Species
What is a serotype?
Subspecies of bacteria defined by the expression of surface antigens
What is a virotype?
A subspecies of bacteria defined by their virulence
Name 5 of the features that phenetic classification is based upon, there are 16 in total.
Cell shape Cell wall constituents Cell size Energy source Colonial morphology Fermentation products Ultrastructural characteristics Growth temperature optimum and range Staining behaviour Osmotic tolerance Mechanism of motility Oxygen relationships Cellular inclusions pH optimum and range Carbon and nitrogen sources Sensitivity to metabolic inhibitors and antibiotics
What is numerical taxonomy?
A system which develops classical classification by using computers to analyse the traits thus removing subjectivity.
What are the 4 chemical and molecular taxonomic markers for bacteria?
Cell wall composition
Membrane lipid structures
Proteins
Nucleic acid compostion
What are the 3 ways of using the nucleic acid composition to compare bacteria?
Guanine and cytosine content
Hybridisation
Gene sequence similarities
What is the smallest free living bacteria?
Mycoplasma genitalium
What is the smallest endosymbiont bacteria?
Carsonella ruddii
What has Craig venter done?
He synthesized the mycoplasma mycoides genome from chemicals
How long did it take for eukaryotes to develop?
2300 mya
How many years did it take got multicellular organisms to develop from eukaryotes?
500 million
What are the two key characteristics of a plasmid?
A heterogeneous group of dsDNA molecules encoding additional features
Promiscuous
What are the possible genetic elements in prokaryotes?
A single chromosome
Plasmid
Bacteriophages
Transposable elements
What are bacteriophages?
Viruses specific for bacteria
What are the two types of bacteriophages?
Virulent- lytic cycle
Temperate- live harmlesly inside bacteria
What are transposable elements?
Jumping genes which can move between and within DNA molecules
What is an insertion sequence?
A transposable element whose only known function is transposition
What are transposons?
Larger versions of ISs that include genes such as antibiotic resistance
What are the three mechanisms of genetic exchange in bacteria?
Transformation
Transduction
Conjugation
What is transformation?
A genetic exchange mechanism that involves the uptake of DNA which is released into the environment by degradation if bacteria
What is transduction?
A method of genetic variation dependent on phages carrying bacterial DNA
What is conjugation?
A method of genetic variation in bacteria which is plasmid dependent. The pilli fuse to create cell to cell contact then the DNA is transferred by rolling cell replication
Name three additional genetic elements of prokaryotes
Plasmids
Bacteriophages
Transposable elements
