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10 Cards in this Set
- Front
- Back
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Describe possible RNA processing modifictions
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1.) Pre-mRNA splicing can produce many different mRNA transcripts from a single gene
2.) Addition of Poly-A tail in different locations can alter the protein product 3.) Addition of trans-acting element can allow mRNA transcript to last much longer in the cell |
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Describe some post translational modifications
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Phosphorylation by kinases to alter protein function
Ubiquidation by addition of short PP sequence alters stability and essentially kills the protein |
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Compare and contrast miRNA and siRNA with respect to:
Origin Function Conservation Mode of action |
Both a short, 18-24 nt sequences
miRNA is from endogenous sources, which produces a stem loop structure siRNA derived from exogenous or endogenous dsRNA miRNA is conserved because it is endogenous miRNA leads to translation inhibition (imperfect base pairing) siRNA leads to mRNA cleavage |
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Describe the mechanism of gene silencing with mi or siRNA
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Dicer cuts up the dsRNA into ~20 nt sequences, the dsRNA becomes ssRNA, which is integrated into the RNA-Induced Silencing Complex (RISC), which then binds to the matching sequence on the target mRNA
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At what points is the flow of genetic information subject to silencing?
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Chromatin - methylation to silence genes
Transcription - trans factors (proteins), and cis factors (promoters, enhancers) RNA Processing - Alt splicing, Poly-A, mRNA stability, mRNA transport Translation - mRNA secondary structure, protein factors, modifications |
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Define the different types of mutations:
Missense: Silent: Transversion: Transition: |
Missense: Alters amino acid
Silent: Does not change AA Transversion: purine to pyramadine or vice versa Transition: Purine to purine or vice versa |
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What are some key characteristics of Noonan Syndrome?
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Short statue
Congenital heart defect (P valve stenosis) Broad or webbed neck Low set ears Triangular face Cryptorchidism Mild mental retardation in 1/3 |
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How is Noonan's diagnosed?
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Primarily clinical grounds
Several genes are associated with a little of 50% of cases (PTPN11) |
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How frequent is Noonan inherited v. de novo? What is the mode of inheritance?
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About 50% of Noonan cases arise de novo
Autosomal dominant |
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How is Noonan related to CFC, Costello, LEOPARD, JMML?
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They all appear to have their origin in the dysregulation of RAS / MAPK / ERK signal transduction pathway; because the mutations may be a different levels of the pathway (Ras v. ERK), the phenotype is different
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