Term
| Genetics of bacteria and viruses |
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Definition
- genes of bacteria are ofund in bacterial chromosomes
- usually a single type of chromosome
- may have more than 1 copy of that chromosome
- # of copies depends on the bacterial species and on growth conditions
- typicall 1-4 identical chromosomes
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Term
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Definition
- molecules of double-stranded DNA
- usually circular
- tend to be shorter
- contains a few thousand unique genes
- mostly structual genes
- single orgin of replication
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Term
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Definition
- typical bacterial chromosome must be compacted about 1,000-fold
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Term
| why does bacterial DNA need to be compacted? |
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Definition
- bacterial DNA is not wound around histone proteins to form nucleosomes
- proteins important in forming loop domains (compacts DNA about 10-fold)
- DNA supercoiling (topoisomerases twist the DNA and control degree of supercoiling)
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Term
what are some characteristics Plasmids?
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Definition
- small, circular pieces of DNA that exist independently of bacterial chromosome
- occur naturally in many strains of bacteria and in a types of eukaryoic cells, such as yeast
- own orgin of replication that allows it to be replicated independently of the bacterial chromosome
- not usually necessary for survival but can provide growth advantages
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Term
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Definition
| plasmid that can integrate into bacterial chromosome |
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Term
| what are the 5 types of plasmids? |
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Definition
- Resistance plasmids (R factors)
- Degradative plasmids
- Col-plasmids
- Virulence plasmids
- Fertility plasmids (F factors)
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Term
| How would you describe Resistance plasmids (R factors)? |
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Definition
| they contain genes that confer resistance against antibodies and other types of toxins |
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Term
| what are degradative plasmids? |
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Definition
| plasmids that carry genes that enable the bacterium to digest and utilize an unusual substance |
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Term
what are Virulence plasmids?
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Definition
| plasmids that carry genes tha turn a bacterium into a pathogenic strain |
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Term
| what is the role of fertility plasmids? |
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Definition
| they allow bacteria to mate with each other. |
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Term
| How can reproduction be described? |
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Definition
- cells of some species, such as E.coli, can divide every 20-30 minutes
- single cell can form a bacterial colony in less than a day
- reproduction by binary fission, execpt when mutation occurs then each daughter cell contains an identical copy of the mother cell's genetic material
- plasmids may replicate indenpendently of the bacterial chromosome
- does not involve genetic contributions from 2 different parents
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Term
| what happens in reproduction what a mutation occurs? |
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Definition
| binary fission does not go through but instead each daughter cell contains an identical copy of the mother cell's genetic material |
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Term
how can you explain genetic diversity?
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Definition
| mutations that occur that after the bacterial genome and affect the traits of bacterial cells |
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Term
| what is genetic transfer? |
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Definition
| genetic material is transferred from one bacterial cell to another |
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Term
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Definition
| direct physical interaction transfers genetic material from donor to recipient cell |
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Term
| what happens in conjugation? |
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Definition
- transformation
- DNA released from a dead bacterium into the environment is take up by another bacteria
- a virus transfers genetic information from one bacterium to another
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Term
| what did Lederberg and Tatum do? |
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Definition
- they demonstrated genetic transfer between bacteria and led to the discovery of conjugation with E.coli
- studied strains of E.coli that had different nutritional requirements for growth, which corresponds to alleic differences between the strain
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Term
| what were conclusions of Lederberg and Tatum working with E.coli? |
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Definition
- when 2 strains were mixed, found new genotypes,not mutation.
- without physical contact, genetic material could not be transferred.
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