Chapter 7: Bacterial and Viral Genetic Systems Flashcards
What did the microorganism experiment with leu- and leu+ bacterial colonies tell us regarding supplemental mediums?
A colony that grows ONLY on the supplemented medium has a mutation in a gene that encodes the synthesis of an essential nutrient
Regarding medium consumption, which two types of bacteria exist?
- Prototrophic
- Auxotrophic
Define prototrophic bacteria
Wild type, can eat anything, can survive off minimum medium
Define auxotrophic bacteria
Cannot eat everything, needs a complete medium
Define minimum medium
A medium with scarely any nutrients, only required by prototrophic bacteria
Define complere medium
Contains all substances required by all bacteria, including auxotrophic bacteria
Are wild type bacteria signaled with a + or a -, what about mutant bacteria?
Wild type: +
Mutant type: -
Ex:
met+ = wild type
met - = mutant type
What does the symbol “s” mean regarding bacteria and antibiotics?
Sensitive to antibiotics
Ex: METs
What does the symbol “r” mean regarding bacteria and antibiotics?
Resistant to antibiotics
Ex: METr
Define plasmid
Extra-chromosomal small circles of DNA
Define conjugation
Direct transfer of DNA from one bacterium to another
What is the difference between transformation and transduction?
Transformation: Bacterium take up free DNA
Transduction: Bacterial viruses take DNA from one bacterium to another
Who all played a role in the discovery of conjugation? (3 people)
William Hayes: Discovered the “F” facotr
Lederberg and Tatum: confirmed recombination took place between 2 mutant strains
What is the F factor, and what does it mean?
F = fertility factor, which means one strain was always the donor while the other was always the recipient.
How are the two strains (donor and recipient) depicted? (X+ and X-)
F+ = donor
F- = recipient
What is an R plasmid?
Like an F plasmid it can rapidly replicate, but it also contains genes from many bacteria
T/F: R plasmids play a role in antibiotic resistance
True