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17 Cards in this Set
- Front
- Back
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What is the role of microRNA? |
Controlling translation of most genes |
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What are the functions of small interfering RNAs? |
Viral defence and experimental tools |
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What is the function of piRNA? |
piwi-interacting RNA important in germ cell production |
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What is the function of long RNA? |
X chromosome inactivation |
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How much of non-coding DNA is functional? How much is transcribed with no known function? |
20% 60% |
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How are inactive X chromosomes removed? |
Lyonised Condensed and packaged into heterochromatin |
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How does dsRNA injection work to limit gene expression? |
Endonuclease dicer creates 21-25bp Argonaute proteins differentiate between sense and antisense of siRNA duplex passenger strand removed siRNA antisense strand remains (comp to mRNA) RISC complex breaks down mRNA complementary to siRNA doesn't work in humans, releases interferons |
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What is the role of dicer? |
Differentiates embryonic stem cells Prevents limb morphogenesis defects etc. |
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Why is siRNA used therapeutically? |
Small enough to enter cell causing detrimental cytokine reactions Turn off genes without causing response |
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How is siRNA synthesised? |
One long piece of RNA that folds back on itself shRNA (small hairpin) |
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How can gene expression be limited in humans? |
siRNA mimics called small hairpin RNAs |
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Why was Lin-14 the subject of miRNA activity research? |
RNA production continues throughout development Protein production ends fairly early Study of RNA control mechanisms |
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Describe the defects caused by Lin14 mis-expression? |
Protein levels should disappear by larval stage 2 Null mutations cause advanced development Prolonged expression causes retarded development |
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What are the functions of Lin-4? |
2 forms: 21 and 61 nucleotides long Regulate Lin14 expression 21bp inhibits protein expression of Lin14 TF by binding to 3' UTR of Lin14 mRNA |
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How are miRNAs synthesised? |
From pri-miRNA Processed and diced to pre-miRNAs Fits RISC complex Some sequences end up as siRNA |
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How can miRNA genes be identified in a genome? |
Two matching areas separated by a bulge Less stringent in order to form shRNA |
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What is the seed region? |
miRNA most important targeting region 5' nucleotides 2-8 |
