Bacterial Genetics Flashcards
What are advantages of using bacteria for genetics?
Easily cultured
Short generation time
Hapoid
Whats the most common used bacteria in lab?
E coli
Describe the DNA structure of E coli
Single circular chromosome
4500 genes
coiled into a nucleoid
What are bacteriophages?
Viruses that infect bacteria
Describe the lytic life cycle of a bacteriophage
Multiply and then lyse the bacterial cell releasing progeny bacteriophage particles
Describe the temperate life cycle of a bacteriophage
Can integrate into the bacterial chromosome and remain dormant, replicating along with the bacterial DNA
What are the 3 ways in which genes can be transferred?
Transformation
Transduction
Conjugation
What is transformation?
Uptake of naked DNA
What is transduction?
Transfer of bacterial genes from one bacteria to another by a bacteriophage
What are the two types of transduction?
Generalised (virulent)
Specialised (temperate)
What is conjugation?
The ability to form sex pili and to transfer DNA by conjugation is determined by a plasmid called an F (for fertility) factor
Explain how the F plasmid controls conjugation inbacteria
The F factor replicates in synchrony with the bacterial chromosome
The F factor replicates in such a way that one end of the DNA molecule passes through the cytoplasmic bridge into the recipient cell where it circularises
The recipient cell is called an exconjugant
The donor keeps a copy of the F factor
What is gene expression in bacteria controlled at?
At the level of initiation of transcription
What is used to control typtophan biosynthesis?
Repressible enzymes
What controls lacctose metabolism?
Inducible enzymes
