Prokaryotic Genomes – Flashcards
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| DNA GYRASE. What kind of coil created? In what? How? |
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| The enzyme responsible for underwinding the double stranded DNA molecule in bacteria. This creates a negative supercoil. |
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DNA Topoisomerase. What uses it? How does it coil? |
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| Enzyme used by archaea to overwind the DNA strands into positive supercoils |
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| Domains (DNA). Why are they important? |
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| relaxed cytoplasmic loops of chromosomal DNA. spaced between sequences of high protein binding. cruicial for prokaryotic gene expression and chromosome replication |
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Quinolones What are they used for? |
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| Inhibit supercoiling, strand nicking and supercoil relaxation that prevent DNA replication. Good antibacterials. |
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Plasmids
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| Circular molecules of supercoiled DNA. Much smaller than a chromosome. encode no essential functions for cell growth. Found in some but not all prokaryotes. |
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| What gene functions do plasmids contain? |
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| antibiotic resistance, metabolism of exotic organic compounds, plasmid incompatibility, cell to cell plasmid transfer and cell segregation |
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Intergenic Distance Prokaryotes vs Eukaryotes |
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| Space between DNA. Also refers to how much "junk DNA" there is between genes. Prokaryotic gene info is spaced b/w 3-9 nucleotides. Eukaryotes have space of 150-350 nucleotides. |
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| Transposable elements |
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| DNA sequences capable of changing their location in a host genome. Also referred to as "jumping genes". RARE CELLULAR EVENT |
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| Nonreplicative transposition |
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| transposable element physically removed from original genome site and reintegrated in a "cut and paste" mechanism to a new genome. |
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| Replicative Transposition |
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| one transposable element remains at its original genome site while a second copy is inserted elsewhere |
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Operons What is their role in DNA replication? |
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| What organizes prokaryotic genes into a single transcriptional unit to be under the control of one promoter. |
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| What protein assists RNA polymerase in binding to a promoter? |
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| Sigma proteins |
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| What do consensus sequence promoters do for DNA replication? What do they produce? |
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| Make it easy for bacterial RNA polymerases to recognize and begin transcription. Produce consistent amountts of protein |
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| What kind of operon would use a weak promoter? |
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| A lac operon or any operon under dynamic control. Allow for more control of gene expression |
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Rho protein What is it? What does it do? |
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| protein that binds to single stranded mRNA molecules. Clamp around mRNA molecules to eventually displace RNA polymerase and end mRNA transcription |
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| Rho-dependent transcription termination |
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| mRNA transcription that is depending on Rho to end |
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Rho-independent transcription termination What does it use instead to end mRNA transcription? |
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| Uses an inverted repeat sequence of DNA that forms a stem-loop structure. is then immediately followed by a series of adenine nucleotides that work to end transcription |
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polycistronic mRNA molecule what is it? what does it contain? |
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| transcribed from operon structural genes. contain ribosome binding, translation initiation and transcription termination sequences. |
