Flashcards in Lectures 8 & 9 - Bacterial Genetics Deck (29):
Give a brief overview of what defines a prokayote
Condensed 'free' DNA
One circular chromosome
Co-transcribed groups of genes -operons
Directional gene transfer
Unequal parental contribution of merozygote
Normally recover only one product from cross over
What are the processes of horizontal gene transfer in bacteria?
How do bacteria reproduce?
What are the technical advantages of using bacteria in genetic technology?
There numbers make it easier to identify rare events
They have rapid growth
They have powerful detection systems
Clonal growth means that reproduction of one particular genome is easy
What is the smallest bacteria?
Mycoplasma genitalium - 580kbp
What is the largest bacteria?
Streptomyces coelicor - 8.67Mbp
What is oriC?
The origin of replication
What is terC?
The termination point
What is it called when there is one replication per cell division?
What is it called when there are multiple replication forks?
How come E. coli can replicate in 20 minutes if it takes 40 minutes to replicate the genome?
Multiple replication forks
What is the gene density of the bacterial chromosome?
What is an operon?
A cluster of genes under the control of a single promoter
What is a plasmid?
A circular piece of DNA separate to the chromosome, which usually contains genes not essential for host growth.
What are the possible roles for plasmids?
What do Agrobacterium Ti plasmids do?
Outline the process of conjugation
Binds to bacteria which does not contain the plasmid
Pore forms between them through which DNA is transferred
Only one strand of the plasmid is transferred
Describe the normal life cycle of a bacteriophage
Adsoption to cell
Injection of DNA
DNA replication and gene expression
Assembly of new phage particles
Cell lysis and release
What is a transposon?
A jumping gene
What is an insertion sequence?
A short DNA sequence that acts as a single transposable element
What is the traditional method of mapping a bacterial genome?
Mapping by co-inheritance
What is the modern method of mapping a bacterial genome?
What is a mutant?
A variant where a characteristic is heritably modified
What is an auxotroph?
A mutant which is unable to produce a certain metabolite
What is the idea behind mapping by co-inheritance?
That the closer two genes are the more likely they are to be co-inherited
What is bacterial transformation?
Gene exchange by the uptake of DNA
Describe the process that led to DNA being discovered as the transforming principle
In 1928 griffiths discovered there was a transforming principle due to the transformation of rough streptococcus pneumonia by dead smooth S. pneumonia in vivo.
Avery then found this principle was DNA
How is mapping by transduction carried out?
Use a phage lysate to infect with three different auxotrophic genes. Use the proportion of auxotrophs. E.g. Arg-, pur- and met- would measure proportion of arg+,pur+ to arg+, met+