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23 Cards in this Set
- Front
- Back
C-Value |
Total genome size |
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C-Value Paradox |
We have unexpected/unanticipated genome sizes, given our knowledge of the size and complexity of the organism ex) Some amebae genomes dwarf that of humans |
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Genome size and coding DNA are correlated in every group of organisms except... |
Land plants and animals |
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In vertebrates, as cell size increases so does... |
genome size |
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Prokaryotes have large population sizes, therefore |
Prokaryotes with slight advantages win out in the tense competition; therefore prokaryote genomes are highly compacted, few "extra" codons |
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Bacterial genomes acquire nonhomologous genes via... |
Horizontal gene transfer: the movement of geneticmaterial between unicellular and/or multicellular organisms other than via vertical transmission (the transmission of DNA from parent to offspring.) |
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What diminishes genome size in prokaryotes? |
Loss of DNA segments encoding active genes OR gene activation forms pseudogenes that are then lost by deletional bias |
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What increases genome size in prokaryotes? |
Gene duplication OR acquisition of nonhomologous genes |
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Deletional bias |
Most organisms (especially prokaryotes) are more likely to lose DNA than gain it; changes in DNA size are more likely to be losses rather than gains |
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G-Value Paradox |
Despite differences in structural complexity, there is comparatively little variation in the number of coding genes or in the total amount of protein-coding sequence among eukaryotes. |
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What percent of the human genome is coding for proteins? |
1.5% |
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What percent of the human genome is transcribed? |
80% |
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Three models of horizontal gene transfer |
Transduction, Transformation, and Conjugation |
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Transduction |
The process by which foreign DNA is introduced into a cell by a virus or viral vector |
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Transformation |
The genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from the cell's surroundings through the cell membrane(s). |
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Conjugation |
The process by which one bacterium transfers genetic material to another through direct contact. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. |
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Introns |
Play a role in the control of expression, but why do eukaryotic organisms have introns while prokaryotic cells don't? |
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"Jumping genes" |
Transposable elements |
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Much of the "extra" DNA in organisms came from... |
transposable elements |
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Transposable Elements |
Genes that contain information for their transposition (some leaving a copy behind as they move to a new position in the genomes). If these move into the coding sequence of a gene, that gene can be "knocked out." These are genomic parasites! |
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LINE-1 Elements |
Long Interspersed Elements are autonomous transposons. These are not actively "jumping" |
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SINE Elements |
Short Interspersed Elements are nonautonomous transposons, which means they are dependent on LINE-1 elements (includes Alu) |
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Three processes that favor transposition |
--Transposition creates additional transposon copies within the genome --Transposition onto an accessory genetic element (ex: plasmid) facilitates the movement of a transposon into a new genome --Transposition copies an element from one chromosome to its homologue (in sexual diploid species), therefore ensuring that it will be present in all meiotic products |