Chapter 8: Microbial Genetics Flashcards
What is pre-transcriptional control?
Two genetic control mechanisms known as repression and induction regulate the transcription of mRNA and consequently the synthesis of enzymes from them. These mechanisms control the formation and amounts of enzyme in the cell, not the activities of the enzymes.
What is repression?
a process by which proteins known as repressors block the ability of RNA polymerase to initiate transcription from induced genes.
What is induction?
the process that turns on the transcription of a gene or genes. An inducer is coded for, and certain enzymes are coded for in its presence.
Base Substitution/Point Mutation
Most common type; where a single base at one point in the DNA sequence is replaced with a different base. Ex. AT might be replaced by GC. This can cause a missense mutation.
What is a missense mutation?
base substitution results in an amino acid substitution in the synthesized protein. (can cause serious things like sickle cell)
What is a nonsense mutation?
Having a stop codon in the middle of anmRNA molecule. This can effectively prevent the synthesis of a complete, functional protein.
What are frameshift mutations?
Where one or a few nucleotide pairs are deleted or inserted in the DNA. Usually results in a long stretch of altered amino acids.
What is transformation?
Genes are transferred from one bacterium to another as “naked” DNA in solution. The mose and the encapsulated vs. nonencasulated vs. heat killed encapsulated was an example of genetic transformation.
What is conjugation?
genetic material is tranferred from one bacterium to another, mediated by a plasmid.
What is a plasmid?
A circular piece of DNA that replicates independently from the cell’s chromosome. It contains genes for sex pili for the transfer of the plasmid to another cell. They can enhance pathogenicity and give cells special capabilities they didn’t have before. They play a huge role in antibiotic resistance.
What is transduction in bacteria?
DNA is transferred from a donor cell to a recipient cell inside a virus that infects bacteria called a bacteriophage or phage.
