Bacterial genome organisation 2 Flashcards
What does DNA gyrase do?
-vely supercoils DNA
What is -vely supercoiling DNA important for?
Replication and transcription
What do histones do?
Anchor the DNA down the middle of the cell
Which type of genes are expressed near the origin?
Most highly expressed genes
Examples of genes that are expressed near the origin?
encoding RNAs, cell division, metabolism
Why are the Most highly expressed genes near the origin?
Those genes are needed straight after replication
Main components of a bacterial gene?
Promoter region, transcribed region, terminator
What is usually in the promoter region of a bacterial gene?
-35 box, -10 box
What is between the promoter region and the transcribed region?
+1, a ribosome binding site
What is an operon?
A cluster of genes, transcribed together, that share regulatory elements within the DNA
What genes may be in an operon?
Genes that are all in a similar process–> e.g. a metabolic pathway
What is a species?
a monophyletic and genomically coherent cluster of individual organisms that shows a high degree of overall similarity
What is a strain?
– individual member of a species w/ slightly diff genomes
What is the genome
the complete set of genetic information in an organism
What is the core genome?
complete set of genes shared by all strains within a species
What is the pan genome?
complete set of all the genes present within a species
What is the accessory genome?
genes not present in all strains (often dispensable, but likely to confer a useful phenotype e.g. antibiotic resistance)
How can a bacterium’s genome be used to predict/understand its function and mechanisms?
Can look for genes e.g. metabolism genes would suggest it isn’t an obligate intracellular
What are plasmids?
Extrachromosomal pieces of bacterial DNA
What are phages?
Viruses that can insert bits of DNA into bacterial chromosomes
What type of DNA is a plasmid?
Circular
What can plasmids provide bacteria with?
Novel function
Two diff lifestyles of a phage?
Lytic cycle and lysogenic cycle
Lytic phage?
Infect the cell, replicate, cell lysis
Lysogenic phage?
Phage chromosome inserted into the host chromosome
What is a pathogenicity island?
Genetic elements acquired via HGT or phages that allow a bacterium to cause disease
How are bacterial genomes plastic?
They can gain and lose DNA quite easily
What must a mutation do in order to become fixed in the populaiton?
Provide a fitness benefit over the original
