Bacterial Genome Flashcards
How is bacterial shape determined
By genes
Which gene in caulobacter causes a curved shape
Crescent in
Name the 6 types of shapes bacteria can be
1- coccus (round)
2- rod (ecoli)
3- spirillum
4- spirochette (wavy)
5- stalk and hypha (budding and appendage)
6- filamentous (long and thin)
What is dna in bacteria condensed into
A nucleoid
How are genes switched on or off during rep
The dna unwinds from the nucleoid
Explain the genome of an ecoli
Circular chromosome
Haploid 1 copy of each chromosome
No introns
No histones
1 oric site
How many bp does ecoli have
4.6 million bp (4,300 genes)
On the chromosome of bacteria, there are clusters of genes expressed on same mrna. What is this called and give example
Operons
Eg lac ZYA
Same sigma factor and stop codon
Other than the lac operon, give another example
Trp operon
Produces tryptophan when needed to make amino acids
Contains 5 cluster genes
What is in the middle of a chromosome inside genomic dna
The NOT1 restriction sites
Sequences dna is cleaved and recognised
Why do plasmids on their genomic dna need to have replication functions
They replicate independently but coordinated to the chromosome to be passed onto daughter cells
Explain what transposons are on plasmids and how they work
Transposons are genes which can be transferred elsewhere ie gene knockin
They contain insert sequences recognised by proteins
which cases them to be cleaved from plasmid or chromosomes
What do transposons usually carry
Genes for antibiotic resistance
What are tra genes found on plasmids
Transfer genes
They encode for things like sex pili which allows conjugation/ transfer
(F plasmid has tra genes)
Other than plasmids , name 3 other mobile elements
1- bacteriophage transduction
2- transposons
3-integrons
What’s the difference between lytic phage and lysogenic phage
Lytic - enzymes get degraded and phages reassemble killing cell
Lysogenic - the insertion of dna is stable and doesn’t kill cell
What allows a phage to bind to a cell
Tail fibres
What on a phage allows it to inject dna
Base plate
What are integrons
Pickup genes which can carry resistance from a cell to another
What is the difference between the pan genome and core genome
Pan genome contains extra genes inherited via transfer like pathogenicity islands, transposons, conjugative plasmids
Explain briefly the steps of next gen sequencing (alternative to dideoxy)
Fragmented ss dna is hybridised with adaptors (nucleotides) then added to flow cell
On to flow cell when adapter binds this causes dna replication via dna pol and bridging occurs across flow cell
This copies the ss dna like a PCR reaction when multiple copies
When primers attach this allows for the comp labelled nucleotides to bind and it shows sequence
What is bioinformatics
After sequencing where amino acids are determined and the structure of the gene appears
Eg identifying the start and stop codon on the ORF
Name some impacts sequencing and bioinformatics has had
1- follow evolution of bacteria and mutations (comparative genetics)
2- allows all mutations to be seen from a small piece of dna responsible for mutation
3- screening for presence of infection and allowing treatment best for them
4- comparing genome with small section rather than full gene mapping
