Bacterial Genetics Flashcards
What does the majority of the bacterial genome encode?
Protein and tRNA
What is interesting about the 16S rRNA of ribosomes in different bacterial strain?
Each bacterial strain has a different 16S rRNA sequence. However, the flanking sequences are the same in every bacteria and that is how is gets transcribed.
What are extra-chromosomal units of the bacterial genome?
Plasmids and bacteriophages
How do plasmids replicate?
Each has an independent origin of replication so it replicates independently of the chromosomal DNA
How do bacteriophages contribute to extrachromosomal DNA?
These bacterial viruses carry a small number of genes that are NOT essential to the bacteria. The genetic material can be integrated to the chromosome of it can be extrachromosomal.
Where are virulence factors encoded?
Plasmids, bacteriophage DNA, and Chromosomal DNA
What are the different genotypes in bacterial genomes?
1- Biosynthetic genes
2- Catabloic Genes
3-Drug resistance genes
What is an operon?
An operon is a single regulatory unit for genes of related function. Therefore, each individual gene DOES NOT have its own regulatory element.
What is an ames test?
A test to see if an agent is carcinogenic to humans. If it is it will mutate bacteria
What can cause mutations in bacterial genomes?
1- Spontaneous
2- Chemical modifying agents
3- Physical agents
What are examples of physical agents that mutate bacterial genomes?
Xray and UV light
What are examples of chemical modifying agents that mutate bacterial genomes?
Base modifying agents, base analogs, and intercalating agents
What are three mechanisms of genetic exchange among bacteria?
1- Conjugation
2- Transformation
3- Transduction
What is bacterial transformation?
One bacteria takes up bits of DNA from its environment (plasmid or chromosomal DNA)
How is acquired DNA incorporated into a bacterial DNA genome?
Honologus recombiation
What is conjugation?
Bacterial version of sex with the transfer of a F plasmid via a sex pilis
What is significant about conjugation?
It is a major way that bacterial drug resistance is transferred to bacteria
What is generalized transduction?
Lytic phage infects bacteria and causes lysis and release of DNA. Bacteriophages then take up this DNA and transmit it to another bacterial cell
What is specialized transduction?
Lysogenic phages insert their own DNA into the bacterial genome and the when it is excised and repackaged there is exchange of DNA. The new phages go to infect other cells.
What are transposons?
Segments of the genome that jump arund
What do transposons encode?
1- transposase enzyme
2- prespressor gene
3- drug resistance gene?
What are pathogenicity islands?
regions of bacterial chromosomes that may have several adjacent genes that contribute to pathogenesisof a disease
How are operons regulated?
They are controlled via inducible expression and inducible repression.
What is inducible expression?
The presence of a chemical can induce expression when bound to the operator region. lac operon example
What is inducible repression?
The presence of the chemical (bound to the operator) inhibits expression
What is a main transcriptional regulator in bacteria?
metabolic products and deficiencies typically directly regulate transcription
Is there RNA splicing in bacteria?
No
