Genetics Flashcards
Purines
- Adenine
- Guanine
Pyrimidine
- Uracil
- Cytosine
- Thymine
Which NT bonding is more stable?
GC 3 H bonds
Denaturation
Separation of strands by breaking H bonds
Annealing
Coming together of strands by forming H bonds
Hybridization
Formation of ds by complementary base pairings of two ss
DNA supercoiling
Twisting of dsDNA allows for packing
Toposiomerase I
Cleaves one strand of DNA to cause relaxation
Topoisomerase II
Cleaves both strand to cause supercoiling (DNA Gyrase)
DNA Gyrase
Cleave both strands of of DNA and a target for certain antibiotics
Drugs that target DNA gyrase
- Quinolone
- Fluoroquinolone (enrofloxacin)
- Novobiocin
Copy number
Number of plasmids per cell
Transposons
Jumping genes. Genes that move from site to site on the same or different chromosome
Why are transposons important
Can move antibiotic resistance to different bacteria and allow spreading of resistance if introduced into plasmids or viruses
Types of transposons
- Insertion sequences (code for transposase gene)
- Transposons
What are bacteriophages
Viruses that infect bacteria. Can be DNA or RNA, ds or ss
Types of bacteriophages
- Lytic
- Lysogenic
Which bacteriophage causes immediate syntheses of bacteriophage DNA?
Lytic
What bacteriophage cycle incorporates its DNA into the bacteria and then divides through cell division?
Lysogenic
Phage conversion
Presence of prophage confers new properties
Phage immunity
Presence of prophage prevents infection by the same phage
What is phage therapy
Therapeutic use of phages to treat bacterial infections could have less affect on normal bacterial flora due to high specificity of the phages. Bacteria can develop resistance to it though
Mutation
Changes in NT that is inherited. Can be good or bad
Recombination
Genes from two different genomes combine
Vertical gene transfer
Mother to daughter cell recombination
Horizontal gene transfer
Donor to recipient cell recombination
Auxotroph mutant
Mutant that lacks ability to make required nutrient and needs it to be provided
Point mutation
Change in single base or NT. Phenotypic change dependent on where it is
Frameshift mutation
Insertion or deletion of several bp
What are the mechanisms of genetic recombination
- Transformation
- Transduction
- Conjugation
Transformation
incorporation of free DNA into recipient
Competent bacteria
Able to be transformed
Transduction
DNA transfer by bacteriophage. Can be generalized or specialized
Conjugation
DNA transfer from cell to cell contact mediated by conjugative plasmid cell. Donor cell has the conjugated plasmid that it gives to recipient