Lecture 36. Prokaryotic Genetics Flashcards
What is bacterial genetics?
Bacterial genetics is the study of the mechanisms of heritable information in bacteria, their chromosomes, plasmids, transposons and phages
What proportion of DNA on earth is bacteria DNA?
~30%
How many bacterial cells are there in the human body?
Approximately the same number as eukaryotic cells
What is the bacterial genome?
A single circular, double stranded DNA chromosome
How long is the length of DNA in an E. coli?
About 1 mile
How do bacteria asexually reproduce?
Binary fission
What is the generation time of E. coli?
~20 mins
When was E. coli adapted as a model organism?
1940s
What is wild type E. Coli?
A phototroph (does not require special nutritional factors)
What are auxotrophic mutants of E. Coli impaired in?
Some metabolic capabilities
What do biosynthetic auxotrophs require in order to grow?
Additional nutrients to synthesise an amino acid, a nucleotide or a vitamin
What can’t catabolic auxotrophs do?
Catabolic auxotrophs have lost the ability to catabolise some carbon source
Why are catabolic auxotrophs rarely a problem?
Glucose is the carbon source of choice
Consequences of possessing any mutation involved in the ability to metabolise glucose?
Usually death
What are housekeeping genes?
Genes essential for survival
What are 4 examples of housekeeping genes in E. coli?
Genes involved in DNA replication, Transcription and Translation, Cell Division and Glycolysis
What are conditional lethal mutants?
Mutations that are lethal in some conditions (repressive conditions) but not in other conditions (permissive conditions)
What are temperature sensitive mutants (ts mutants)?
Mutants that only grow at a permissive temperature (usually 30°C for E. coli and not at a restrictive temperature (37°)
What are cold sensitive mutants (cs mutants)
The opposite of ts mutants e.g., they might grow at 37°C but not at 30°C.
In gene annotation, what do three lower case letters indicate?
Three lower case letters indicating a biochemical pathway of process in which the gene product is involved
In gene annotation what does the capital letter after the three lower case letters denote?
The actual gene
In gene annotation, what do the numbers after the capital letter denote?
The allele
In gene annotation, what must the letters and numbers be in?
Italics
Nomenclature of phenotype
Strain phenotype described using same three letter mnemonic as genotype
First letter is capitalised, three letters not italicised
Thr- = requiring threonine (superscript -)
Leu+ = not requiring leucine
