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Are bacterial cells haploid or diploid?
What are the three types of genetic transfers in bacteria?
What is the difference between vertical and horizontal transfer?
- Vertical transfer : binary fission.
- Horizontal transfer : genetic transfer without self reproduction.
What are general characteristics of plasmids?
- Double stranded
- Independent replication from the bacterial chromosome
- 1-200 kbp
Conjugation occurs between cells of _____.
- Opposite mating types F+ & F-.
- (Bacteria with F factor plasmids and bacteria without F factor plasmids.)
What are Tra genes used for and how many are there?
- Products of these genes are necessary for transfer between touching bacteria.
_____ are plasmids that can be intergrated into bacterial chromosomes.
Describe the physical process of conjugation.
- Occurs when donor cell attaches itself to the recipient cell via sex pilus.
- Sex pilus shortens drawing the two bacteria together and a cytoplasmic bridge then forms between the cells.
What is relaxosome?
A protein complex coded by the F factor. It recognizes a specific DNA sequence in the F factor known as the origin of transfer. It also catalyzes the seperation of TDNA from its complimentary strand.
Most proteins within the relaxosome complex are released from tDNA, except for what?
The F factor, besides coding for relaxosome, codes for what?
large complex of proteins (exporter) that spans both inner and outer membrane of donor bacterium.
_____ is recognized by a coupling factor that promotes its entry into the exporter and through the conjugation bridge into recipient cell.
What catalyzes the TDNA ends together to a single strand plasmid?
What is an F' factor?
An F factor that contains genes that were once part of the bacterial chromosome.
What is an Hfr strain?
An f factor that has become intergrated into the bacterial chromosome.
When DNA transfer begins, the Hfr cell tries to transfer what?
The entire bacterial chromosome to the F- cell. The chromosome will be the the first DNA transfered and the F factor will be the last.
What researchers used Hfr transfer to map out gnen loaction in the bacterial chromosome?
What is a Merozygote and how is it formed?
- A bacterial cell is in the diploid state.
- Hfr cell passes chromosomal DNA from chromosome to plasmid. The F' cell now goes through conjugation with an F- cell sending the plasmid accross that contains chromosomal DNA.
Described how gene conversion takes place in bacteria/
Transfered DNA (plasmid) and the homologous region of DNA transfered to another cell. The homolgous region is exchanged via crossing over.
What is a bacteriophage?
Composed of genetic material surrounded by protein coat that can highjack DNA replication machinery of a host cell.
What are the two types of cycles that a bacteriophages?
- Lytic : is active is the active form.
- Lysogenic : is dorment for a period of time.
What is a prophage?
A hybrid of viral DNA and bacterial DNA after a lysogenic virus infects a cell.
Describe the generalized process of Transduction.
Phages being assembled in the host cell can contain host DNA rather than viral DNA. The phage with host DNA inserts the chromosomal DNA from one bacteria to the next.
Describe the process of Transformation.
Bacteria take up pieces of DNA from dead bacteria from the enviornment.
Cells that are able to take up DNA are called what?
Who is Fred Griffith?
English researcher who studied the spanish flu and showed that bacteria could take up DNA from the heat killed S strain.
Who are Avery and McLeod?
Continued Fred Griffith's research and figured out Transformation.
Transformation can be artificially produced by what?
- Heat shock
- Chemically with calcium ions
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