Bacterial genome organisation 1 Flashcards
What kind of genome do most bacteria have?
Circular
What kind of genome do streptomyces have?
Linear
What is bacterial DNA stored in?
Chromosomes and plasmids
How is a chromosome depicted when in a paper?
A circle
What can plasmids do?
Give bacteria extra propertie
What are the two strands of bacterial genomes called?
Leading and lagging strand
Where does DNA replication begin from in bacteria?
The origin
In which direction can bacterial DNA replication go?
Both
Which strand can be used for replication in bacteria?
Leading and lagging
What can differences in CG content of bacteria show?
Where horizontal gene transfer has happened
What are features of interest in a bacterial genome?
rRNA genes, RNA genes, tRNA genes
What mutational bias occurs involving Gs and Cs?
More Gs on the leading strand compared to the lagging strand
What is the relationship between genome size and number of genes in bacteria?
Linear
What proportion of every bacterial genome is unique to that organism?
20-40%
Which type of bacteria have the most DNA?
Soil organisms
Why do soil organisms have the most DNA?
They need to be able to cope with the different conditions that they could be in
What do bacteria with small genomes have to do?
Rely on other organisms for their function
Examples of things that bacteria may rely on other organisms for?
Osmotic balance, metabolites, AAs
Why do obligate intracellular bacteria not always cause disease?
They rely on the host for some functions
Why may a bacteria have a large genome?
Needs to do a lot of its own stuff–> i.e. metabolism etc
Which bacteria is involved in antibiotic production?
Streptomyces
How does a bacterial genome fit into a bacterial cell?
Supercoiling
What are the two types of supercoiling?
Overwound DNA and underwound DNA
Characteristics of overwound DNA?
Tightly wound
+vely supercoiled
Strands difficult to separate
harder for metabolic fucitons to take place
Characteristics of underwound DNA?
Underwound
Negatively supercoiled
Strands easier to separate
Which type of supercoiling is harder to do?
Positive (overwound)
How many base pairs per turn does overwound DNA have compared to underwound DNA?
Less
bp per turn of overwound DNA?
less than 10.4
bp per turn of underwound DNA?
more than 10.4
How is DNA underwound?
Breaking the DNA and passing the strands through to change the # of twists, before fixing the DNA
Type 1 of underwinding DNA?
breaks 1 strand, no ATP
Type 2 of underwinding DNA?
breaks 2 strands, ATP
