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24 Cards in this Set
- Front
- Back
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Are bacteria diploid or haploid?
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Bacteria are haploid
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E coli have how many potential genes?
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~4300
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Are viral chromosomes always circular
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No. Can be linear or circular
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Which is the most common mode of prokaryotic DNA replication?
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Theta (θ)
Used to replicate chromosomes, plasmids, some viruses |
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How does the theta mode of replication work?
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Replication at a single origin, proceeds bidirectionally.
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How does the rolling circle mode of replication work?
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nick is made in the template and the template rolls around, replicated strands rolls off.
Some viruses & plasmids |
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How does the Sigma mode of replication work?
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Sigma: Only one copy of single stranded DNA is rolled off
Some viruses, conjugative plasmids |
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How does the End replication mode of replication work?
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for linear DNA, protein on the end serves as a primer for synthesis of the daughter strand.
Some viruses |
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True/False?
The basic enzymology of DNA synthesis is the same in prokaryotes & eukaryotes |
True
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What enzymes unlink the concatenated daughter chromosomes after theta DNA replication?
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DNA gyrase and topoisomerases
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What is an insertion sequence?
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DNA sequence that has inverted repeats on the end, and in the middle is a gene that encodes for an enzyme that recognizes the inverted the repeats and take that whole gene and moves it from one piece of DNA and inserts it into another piece of DNA.
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What is a transposon?
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two insertion sequences that flank another piece of DNA. Often these pieces of DNA contain genes for antibiotic resistance or products that are toxic to humans.
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minimally Plasmids must have...
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a) means of initiating replication
b) mechanism to ensure maintenance and partitioning |
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Low copy plasmids coordinate replication with...
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Chromosomes
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Plasmid partitioning strategy depends on what?
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The copy number of the plasmid.
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What is an "addiction plasmid?"
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Plasmid makes two different proteins, one that is cytotoxic to the host cell. The antitoxin has a shorter half-life than the toxin so that the plasmid must be present to keep making the antidote. If a cell is produced that doesn't have the plasmid, it will inherit the toxin in the cytoplasm, but the antidote will degrade before the toxin, killing the cell.
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What are the Three ways bacteria can exchange genetic material?
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1. Transformation:
uptake of “naked” DNA molecules from extracellular environment 2. Conjugation: Bacterial sex 3. Transduction: Bacteriophage-mediated transfer of DNA |
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True/False
All species of bacteria have natural ability for DNA uptake |
False
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What does Merodiploid mean?
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diploid for only a portion of the genome
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What are the three stages of the Lytic cycle of phage infection?
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1. Phage absorbs to receptor on cell and injects its genome
2. Phage DNA replication and synthesis of virion proteins 3. Phage virions are assembled and released (usually via cell lysis) |
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What is Lysogeny?
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After genome injected into host cell, phage senses some signal indicating lytic growth is not desirable at this time, so it integrates into the host chromosome to be replicated passively
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How does Lambda specialized transduction work?
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Most phage have a preference for where they want to integrate into the host DNA. Sometimes when the viral genome is excised, it picks up parts of these genes. These genes can then be passed on to other bacteria.
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How does Generalized Transduction work?
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Lytic bacteria can transduce any portion of the host chromosome into a new bacterial cell because in the frenzy of encapsulating phage DNA, host DNA fragments can be easily picked up.
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What is Lysogenic conversion?
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When the presence of a lysogenic prophage confers a new property to the host bacterium
example is the gene for Diphtheria toxin carried by a temperate bacteriophage of Corynebacterium diphtheria : only lysogens having the prophage are pathogenic |
