Microbial Genetics Flashcards
What is a conjugative plasmid?
carries genes necessary for transfer of plasmid to another cell
Dissimliation plasmid are?
encodes for enzymes that catabolize unusual compounds.
Some species of Pseudomonas can actually use such exotic substances as toluene, camphor, and hydrocarbons of petroleum as primary carbon and energy sources because they have catabolic enzymes encoded by genes carried on plasmids.
R Factors are?
encoding resistance to antibiotics and or heavy metals
Bacteriocins are proteins made by?
Ribosomes.
Bacteriocins and antibiotics are different how? Similar?
Bacteriocins are made by ribosomes. Similar by killing species.
Lac - Means?
Cannot utilize lactose or lacking lactose
Str(r) Means?
Resistant to the antibiotic streptomycin
Deletion of a gene is denoted by?
Triangle (delta)
Plasmid C has a defect in rsp43 and is resistant to streptomycin. What function does rsp43 have?
A function that streptomycin would attack.
What is ORF?
Open-Reading Frame.
What do the numbers represent in the genetics map of the chromosome of E. Coli?
Time of conjugation
Why use a RNA primer?
To make sure the DNA polymerase removes it.
Which topoisomerase uses ATP?
Topo II (gyrase)
What do DNA gyrase and Histones have in common?
DNA gyrase compacts the bacterial DNA. Eukaryotes use histones to compact DNA.
Table 8.1
Important Enzymes
How are bacterial organisms capable of doubling replication time? (E. Coli 40 mins to 20 mins)
They can begin another replication of their DNA when they are halfway through.
The terminator site is mediated by Rho. What mechanism does it have?
It’s a specific sequence that terminates transcription in prokaryotes.
Rho-independent has what mechanism?
creates a loop with a stem of UUU’s and the polymerase falls off.
Stop Codons (3)
UAA, UAG, UGA
What does “degenerate” mean?
Multiple codons can code for the same amino acid
80% of the codons found in genome X, code for CCU, 20% code for CCA. What explains the frequency if they both code for Proline?
Codon Bias- the frequency of different codons for the same amino acid could be different?
In Prokaryotes: What is the Shine–Dalgarno (SD) sequence
A region before translation leading to the start codon,
Repressor gene?
The default position is on.
Inducible gene?
The default position is off. It binds the repressor protein and takes it off.
The operator is?
Where the repressor binds.
Beta-Galactosidase
Cleaves the Beta linkage in lactose to form glucose and galactose.
Cleaving galactose can switch the bond between two sugars and create?
Allolactose.
If Lactose and glucose are present…?
There will be no transcription.
If Lactose is present and glucose is not
Transcription will occur.
Low glucose means the activator will bind, what does that mean?
More cAMP (activator), more transcription.
(Trp Operon) what regulates it?
Tryptophan.
What does Allolactose regulate?
The repressor.
What can activators do?
Recruit the polymerase to bind.
What do CG nucleotides cause in the eukaryotes?
methylation (silencing genes)
What do GA/TC nucleotides cause in the prokaryotes?
methylation and is important for restriction-modification.
Post-transcriptional control in bacteria? (4)
1) mRNA stability
2) Translation
3) Protein stability
4) Regulatory RNA molecules; miRNA (Euk) and sRNA (Prok)
Transitions are?
Purine to Purine
Transversions are?
Purine to Pyrimidine vice versa
Point Mutations are?
One base pair change.
Base modifiers are
nitrous acid; change the nucleotide to bind a new nucleotide. C to A.
Base analogs are
intercalation of the planar molecule can distort base stacking
What is the use of velveteen?
Used in indirect and direct selection to imprint colonies.
What does the AMES test do?
Testing for cells that do not have a functional histidine gene.
It looks for gene mutations in bacteria. If the substance has the ability to cause a mutation in the bacteria, it might be able to cause mutations in humans as well, and should therefore undergo further testing to determine whether it is safe or not.
What is a highly competent bacterial cell capable of doing?
Greatly able to take up genetic information in transformation.
Hfr stands for what?
High-frequency recombination.
Why don’t [F-] cells become Hfr cells?
There is no homology for the F region in the chromosome found in the Hfr cell.
Generalized transduction is?
Phages packages (any) piece from the chromosome.
Specialized transduction is?
Phage packages only specific genes and creates a hybrid and a normal bacterial cell, creating two different phages.
Cotransduction is the frequency of?
Two genes transducing together.
Transposons are?
jumping genes can carry antibiotic resistance move via gene transfer.
E. Coli 0157:H7 acquired the toxin gene by?
Specialized transduction.
