Variations in genome structure--> prokaryotes 1 Flashcards
Which types of organism dont have a nucleus?
Prokaryotes and archaea
Genome structure of prokaryotes?
Nucleoids
Compact efficient genomes
Plasmids
What are nucleoids?
Small, circular chromosomes
How are prokaryotic genomes efficient?
Few non-coding regions
Benefit of prokaryotes having v efficient genomes?
Allows quick reproduction and adaptation to changing environments
How does replication work in a circular chromosome?
Starts at the oriC and goes around in both directions
Speed of DNA pol in pro vs eu?
10* faster in pro
Issue w/ DNA pol working v quick in pro?
Lots of errors–> can’t proofread DNA
How does evolution occur faster in prokaryotes?
Replication error rate is higher
What are plasmids?
Small, circular DNA elements separate from the main circular genome
What do and dont plasmids carry?
Do–> adaptive genes
Done–> genes essential for cell function
What sort of adaptive factors can plasmids carry?
antibiotic resistance, virulence factors, metabolic capabilities
How can plasmids be transferred?
HGT
How can plasmid borne genes be permanently integrated?
If they incorporate into the main nucleoid
Benefit of plasmids?
Allow nucleoid to remain stable while they drive evolutionary change
Main driver of genomic variation in bacteria?
Plasmids
What is HGT?
Exchange of genetic material between organisms that are not parent and offspring
Main mechanisms of HGT?
Conjugation, transformation, transduction
What is conjugation in HGT?
Direct transfer between cells
What is transformation in HGT?
Uptake of environmental DNA
What is transduction in HGT?
Viral mediated transfer
How is bacterial DNA packaged?
Supercoiling
What is supercoiled dna?
DNA that has been over/underwound
Is most bacterial DNA over or underwound?
underwound-> preferred mechanism
