Chapter 7- Genetic transfer and mapping in bacteria Flashcards
What is genetic transfer?
It happens when segment of genetic DNA is transferred from one bacteria to another.
What are the differences between gram positive and gram negative?
Gram positive has think layer of peptidoglycan. However, gram negative have think layer of peptidoglycan.
What are phototrophs?
They are bacteria that can grow on minimal media. In another word, they can synthesize the essential nutrients that they need.
What are autotrophs?
Bacteria that grow on complete media. They are bacteria that are unable to synthesize the essential nutrient that they need.
What are the three ways of genetic transfer?
- Transformation (involves uptake from the environment)
- Transduction (involves bacteriophages)
- conjugation (involves direct physical contact)
What is plasmid?
It is extra chromosomal DNA.
Are plasmid linear or circular?
Most plasmid are circular, however some are linear.
What type of cell does plasmid exist in?
It is found in many bacteria and few Eukaryotic cells.
Does plasmid replicate dependently or independently of host chromosomes?
It replicates independently.
Are plasmid required for survival?
No, they are usually not required for survival but they provide growth advantages to the bacteria.
What is Polylinker?
It is where scientist insert genes into plasmid.
What does the arrow in plasmid diagram means?
They tell the direction of gene transcription.
What does the boxed in plasmid diagram means?
They are direct nucleic acid sequences repeats.
How does transformation process occur?
A bacterial cell dies releasing a fragment of its DNA into the environment. A recipient bacteria pick up the fragment and incorporate into its chromosomes by recombination.
How does conjugation process occur?
A direct physical contact is needed. The donor cell transfer a segment of DNA to the recipient.
How does transduction process occur?
A bacteriophage infect a donor cell. It incorporate a segment of bacterial DNA into a newly made phages. The phages then transfer the DNA fragment into the recipient cell, which incorporate the DNA into its chromosomes by recombination.
How could bacteria become artificially competent?
- electro-shock
- chemical treatment
- Heat shock
How many crossover is needed to incorporate the new DNA fragment?
Two crossovers is needed to eventually replace the transformed DNA into the host chromosome.
What are the laboratory method used for artificial transformation?
- Calcium chloride + high temperature shock
2. Electroporation
What is the mechanism steps of conjugation transfer?
- Relaxosome recognize the origin of transfer and makes a cut in the DNA
- Relaxosome, the most accessory point, releases relaxase
- the relaxase proteins attaches to the end of the T DNA making a TDNA/ relaxase complex which get transferred to the exporter.
- The coupling factor recognizes the complex
- The exporter pump the complex from the donor cell through conjugation bridge to the recipient cell
- In the donor cell, the F factor get replicated to become double stranded again.
- In the recipient cell, the F factor also get replicated to become double stranded DNA.
How is HFR cell is fromed?
It is formed when the F factor get integrated into the cell chromosome.
What is bacteriophages composed of?
It is composed of genetic material surrounded by a protein coat.
