Flashcards in L8_Bacterial Genetics Deck (20)
Describe the number of genes, ploidy, chromosome(s), and extrachromosomal DNA of bacteria
~4000 genes, haploid, one circulate dsDNA chromosome, circular plasmids and phage particles
Is phage DNA or plasmids essential to bacteria?
Phage and Plasmids code for virulence factors in many bacteria, name a few examples.
Enterotoxin (E. Coli and V. Cholera)
Exofoliatin (S. Aureus)
Erythrogenic Toxin (S. Pyogenes)
Neurotoxin (C. Tetani)
Is there post-translational regulation and or RNA splicing in bacteria?
Describe the difference between eukaryotic and prokaryotic gene regulatory elements.
Each eukaryotic gene has its own promoter and regulatory elements, whereas prokaryotic genes of similar function are usually grouped together and regulated by a single promoter and regulatory elements (operon)
Describe the difference in the type of regulatory elements that effect gene transcription in eukaryotes and prokaryotes.
In eukaryotes genes are regulated by multiple coordinated transcription factors where as in prokaryotes genes are often directly regulated by metabolic products or deficiencies. (multiple transcription factors vs operator/repressor system)
What is special about the 16S RNA gene in bacteria?
It is unique between each species of bacteria but is flanked by highly conserved regions allowing it to be sequenced in order to ID species. (Future of bacterial diagnosis)
What are the 3 major factors that regulate gene expression in bacteria
nutritional status, cell-surface sensing, Quorum Sensing
What are the three main types of exchange of genetic information between bacteria?
Transformation, transduction, conjugation
How do bacteria recognize foreign DNA and degrade it?
They methylate their own DNA so they can recognize it and they degrade foreign DNA with different methylation patterns. This is why genetic exchange is rare overall.
What is the symbol to designate a male bacteria with the F gene integrated into the chromosome?
What are the two types of Transduction?
Generalized and Specialized
What is an R factor
A segment of non-chromosomal DNA that carries gene(s) for antibiotic resistance. (Large ones are called F-factors and generally carry resistance to multiple antibiotics)
Is phage bacteria extrachromosomal or integrated?
Can be either
Why is genetic exchange relatively rare in bacteria?
Do to gene modification, mainly methylation, each bacteria has its only signal of "self", foreign DNA is usually cleaved by restriction enzymes
What type of bacteria have a higher frequency of genetic exchange, gram pos or gram neg?
Gram Negs like to get it on
Describe generalized transduction
Lytic phages can infect bacteria and cause lysis-this can release DNA which can be taken up by the bacteriophage and carried to another bacterium
Describe Specialized transduction
Lysogenic phages can insert themselves into the bacterial chromosome and later can excise themselves along with some adjacent bacterial DNA which can be carried to a new bacterium (transfer of toxins)
to pathogenicity islands have intrinsic relocation mechanisms?