Lecture 4: Bacterial Genetics Flashcards
What perfect of bacterial and human genomes have known function?
75% B
10% human
What shape is bacterial DNA, and how many genes?
Circular
2,000-5,000 genes
Why is the 16sRNA gene the genetic basis for identification and classification of bacteria?
Both conserved and variable regions
In bacteria, what is an operon?
Genes with related function that all share the same regulatory elements
What substances regulate transcription in humans and bacteria?
Humans: proteins interact with promoter
B: metabolic products or deficiencies (nutritional status)
In addition to nutritional status, what regulates bacterial transcription?
Cell surface sensing
Quorum sensing
What test uses bacteria to predict if an agent could be a carcinogen to eukaryotic cells?
Ames test
Which more commonly leads to antibiotic resistance:
Mutations in B Chromosome, or
Acquisition of genes from other B?
Acquisition of genes
Which method of gene exchanged involves DNA from dead bacteria taken up non-specifically by live bacteria?
Transformation
Which method of gene exchanged allows the S. pneumonii capsule gene to be transferred?
Transformation
What are practical uses of transformation?
recombinant hepatitis B vaccine, recombinant insulin,
and virus vectors for gene therapy
Why is gene exchange by transformation and recombination rare?
Restriction/modification mechanism
DNA with defined patterns is methylated
Non-host DNA is modified differently than host
Restriction enzymes digest non-host DNA
Which gene exchange method is characterized by the F factor plasmid, sex pili, and live bacteria?
Conjugation
Which gene exchange method transfers antibiotic resistance genes among intestinal bacteria?
Conjugation
Define Hfr as it relates to conjugation
Make with integrated plasmid due to high frequency of recombination
Which gene exchange method involves a virus which mediates genetic exchange between bacteria?
Transduction
What is generalized transduction?
Lyric
Lyric virus infects bacterium, DNA is released, taken up by bacteriophage virus and carried to another bacterium
What is specialized transduction?
Lysogenic
Bacteriophage inserts into B chromosome (lysogeny), produces prophage in xs. Prophage excised itself and bring adjacent B DNA with it. Carried to another bacterium
Through what gene exchange method are toxins for diphtheria, botulism, cholera, and scarlet fever transferred?
Transduction
What are segments of non-xs DNA that carry genes for antibiotic resistance called?
R-factors
What is an at factor which is also an F factor?
A large R factor plasmid
What are the two mobile genetic elements?
Transposons and integerons
What do compound transposons confer?
Multi-drug resistance
What types of genes do transposons usually encode?
Enzymes for drug resistance
