L4: Bacterial Genetics Flashcards
How can microbial genetics be used?
To breed strains of microbe which have desirable characteristics.
What is microbial genetics?
The study of the inheritance of the characteristics of a microbial cell and how these characteristics can vary.
How can microbial genetics help us?
It helps us to understand how microbes become RESISTANT to antimicrobial agents
and how to prevent such resistance emerging.
Name two ways in which genetic material can exist within bacteria.
Bacterial chromosome
Plasmid
What does a nucleoside contain?
A pentose sugar and a base.
What does a nucleotide contain?
A pentose sugar, a base and a phosphate group.
During replication of the bacterial chromosome which enzyme is involved in adding nucleotides to the new strand?
DNA polymerase.
What are genes?
units of genetic information, grouped together as operons.
What are structural genes?
CISTRONS.
Segments of the chromosomes that can code for proteins.
After transcription what type of ribosome does the mRNA bind to?
30s subunit, which is associated with a 50s ribosome to form a complete working ribosome
What are the general principles of a plasmid? (4)
1) Small circular/linear DNA molecules.
2) Range in size from 1 kbp to > 1mbp
3) Carry variety of nonessential, but often very helpful genes.
4) Abundance is variable
What are R plasmids?
Resistance plasmids
What do resistance plasmids do?
Confer resistance to antibiotics and other growth inhibitors.
What is phenotype?
Observable properties of an organism.
Characteristics that are expressed.
What is a mutation?
A heritable change in DNA sequence that can lead to a change in phenotype.
What is a mutant?
A strain of any cell or virus differing from paternal strain in genotype.
What are selectable mutations? (2)
Those that give mutants a growth advantage under certain environmental conditions.
Useful in genetic research.
What are nonselectable mutations? (2)
Usually have no advantage/disadvantage over parent
Detection of such mutations requires screening large numbers of colonies.
What are induced mutations?
Those made deliberately.
What are spontaneous mutations? (2)
Those that occur without human intervention.
Can result from exposure to natural radiation or oxygen radicals.
What are point mutations? (2)
Mutations that change only ONE base pair.
Can lead to single amino acid chain / no change at all.
What is silent mutation?
Mutation that does not affect amino acid sequence.
What is missense mutation?
Amino acid changed
Polypeptide altered
What is nonsense mutation?
Codon becomes a stop codon
–> polypeptide is incomplete.
