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18 Cards in this Set
- Front
- Back
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What are the types of histone tails modifications? |
K acetypation (Kac) K methylation (Kme) R methylation (Rme) Phosphorylation (S/Tp) Ubiquitylation (Ku)
K: Lysine |
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What are the enzymes in lysine modification reactions? draw. |
Methylation: HMT Demethylation: HDM Acetylation: HAT Deacetylation: HDAC |
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What are the functions of histone modification? |
Acetylation especially, is important in chromatin state transformation. HAT: decoiling and euchromatin HDAC: recoiling and heterochromatin |
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What are the layers of epigenetic control? |
DNA methylation: silence the parts of DNA for good: on cytosines. Histone acetylation miRNA |
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What are the examples of activation and repression of gene expression of histone modification? |
H3K4me1&2: activation/repression 9,2 ; 27,3 repression acetyl group all activation |
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What is the enzyme for methylating DNA cytosines? |
DNA methyltransferases DNMTs |
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Where can you find methylcytosines? |
In transcriptionally silent regions. Replication still occurs. |
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How is the flowering controlled in Arabidopsis? |
FLD gene: produces deacetylase enzyme which keep the FLC: flower repressing gene unavailable for transcription, so can flower. |
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What are needed to transcribe and where do they bind? |
transcriptional factors, RNA polymerase. bind promoter. Activator protein: bind regulatory promoter and enhancer. The one binding enhancer interact with basal transcription apparatus through a mediator. |
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What's a consensus sequence? |
Calculated order of most frequent nucleotide or amino acid resides in a sequence |
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What's an insulator? |
Genetic boundary element that stops the enhancer from promoting a gene transcription if it lies in between of them |
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How does Drosophila (fruitflies)'s sex determined, originally? |
The X:A ratio of chromosomes. If 1.0, female. If 0.5, male. |
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How does Drosophila (fruitflies)'s female sex determined, in more details? |
1.0 X:A ratio activate sxl (sex-lethal) gene. produce sxl protein, tra pre-mRNA spliced downstreamly, produce Tra protein. Tra and Tra2 act on dsx pre-mRNA, spice at female-specific site. |
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How does Drosophila (fruitflies)'s male sex determined, in more details? |
0.5 X:A ratio doesn't activate sxl gene, no sxl protein produced. tra pre-mRNA spliced at upstream site, produce no functional protein. dsx pre-mRNA splice at male-specific site. |
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How is siRNA generated and how does it control RNA silencing? |
From the dicing of double stranded RNA, each siRNA binds mRNA and RISC, and pairs mRNA, cleaves, mRNA degraded. (or inhibition of translation) |
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How is miRNA generated and how does it control RNA silencing? |
From the dicing of double strands on a looped RNA. Each diced miRNA binds a RISC, Paired imperfectly to an mRNA Inhibition of translation |
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What can siRNA do to a mRNA? |
Inhibition in transcription, translation, breakdown of mRNA |
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How does siRNA inhibit transcription? |
By binding to complementary sequences in DNA, through enzyme RITS, Attracting methylating enzymes, Histones or DNA are methylated. Transcription inhibited. |
