Bacterial genetics

Question 1

Bacterial genetics are increasingly being used in veterinary - what are these uses?

Answer 1

1) Detection (e.g., PCR)
2) Identification (e.g., whole genome sequencing
3) Epidemiology (e.g., identify variants of concern, disease transmission pathways
4) Determining antibiotic resistance and presence of virulence factors

Question 2

What is the nucleoid

Answer 2

A bacterial chromosome which is one large circular molecule (haploid)

Question 3

How much longer is a nucleoid compared to a bacterial cell and what is its structure?

Answer 3

1000x longer than a bacterial cell and extensively folded to form a dense body that can be visualised by electron microscopy.

Question 4

How many base pairs does a nucleoid have?

Answer 4

0.8-0.4x10’6

Question 5

One copy of what is given to the daughter cell>

Answer 5

Nucleoid

Question 6

What is a plasmid

Answer 6

A plasmid is a large circular molecule of double-stranded DNA that replicates autonomously from the chromosome

Question 7

What does a plasmid encode for?

Answer 7

Encodes genes for self-transmissibility

Question 8

What do virulence factors help bacteria to do?

Answer 8

Help bacteria to infect humans, animals and plants by a variety of mechanisms

Question 9

What are ways virulence factors can help bacteria?

Answer 9

• Some are toxins that damage or kill animal cells
• Others help bacteria attach to and invade animal cells
• Others protect bacteria against retaliation by the immune system

Question 10

What are 2 examples of virulence plasmids?

Answer 10

Anthrax and E.coli

Question 11

What is a mutation?

Answer 11

An alteration of the nucleotide sequence from the wild type

Question 12

What is a phenotypic adaptation?

Answer 12

Metabolic adjustment in the whole population to environmental conditions

Question 13

What is genetic variation?

Answer 13

The presence of differences in sequences of genes between individual organisms of a species

Question 14

How does genetic variation enable?

Answer 14

Enables natural selection, one of the primary forces driving the evolution of life

Question 15

What does genetic variation within a group enable?

Answer 15

• Enables some organisms to be survive better than others in the environment in which they live
• Organism of even a small population can differ in terms of how well suited they are from life in a certain environment

Question 16

Genetic variation within a species can result from a few different sources - what are these?

Answer 16

• Mutations, the changes in the sequences of the genes in DNA
• Gene transfer
• The movement of genes between different groups of organisms

Question 17

What is mycobacterium bovis and where does it reside?

Answer 17

The causative organism of bovine TB
It resides within granulomas of the lung and draining lymph nodes with very little access to other organisms

Question 18

Mycobacterium bovis has little to no opportunity for gene transfer so how is genetic variation generated?

Answer 18

Generated by point mutation, gene duplication and indels (insertion or deletion of bases in the genome)

Question 19

Where do E.coli and salmonella reside?

Answer 19

They reside in the intestine which are rich in bacteria

Question 20

How do E.coli and salmonella approach genetic variation?

Answer 20

In this environment, gene transfer mechanisms are commonly used to generate genetic variation and to rapidly disseminate advantageous genetic info between organisms