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34 Cards in this Set
- Front
- Back
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Genetic Polymorphism
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-When alleles are so common they appear in more than 1% of the chromosome in the general population.
-*Rare Variants- alleles with frequencies of less than 1% |
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SNP
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-Single Nucleotide Polymorphism
-A Polymorphism |
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RFLP
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-Restriction Fragment Length Polymorphism. (Southern Blotting)
-RFLP- may arise from deletion or insertion of DNA rather than from a SNP |
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VNTR
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-Variable numbers of tandem repeats
-Normal variant |
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Mechanisms of Gene Mutations
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1. Errors introduced during the normal process of DNA replication
2. Mutations arising from a failure to repair DNA damage |
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Genetic Mutation
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-Chromosome missegregation
-Most common mutation |
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Chromosome Mutation
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-Chromosome rearrangement
-Frequently seen in cancer cells |
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Gene Mutations
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-Base pair mutation
-Alters individual genes |
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Germline Mutations
vs. Somatic Mutations |
Inherited vs. Cancer
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DNA Repair Mutations
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-Xeroderma pigmentosa
-Ataxia telangiectasia -Fanconi anemia -Bloom syndrome -Some cancers (HNPCC) |
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Genetic Polymorphism
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-When alleles are so common they appear in more than 1% of the chromosome in the general population.
-*Rare Variants- alleles with frequencies of less than 1% |
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SNP
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-Single Nucleotide Polymorphism
-A Polymorphism |
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RFLP
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-Restriction Fragment Length Polymorphism. (Southern Blotting)
-RFLP- may arise from deletion or insertion of DNA rather than from a SNP |
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VNTR
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-Variable numbers of tandem repeats
-Normal variant |
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Mechanisms of Gene Mutations
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1. Errors introduced during the normal process of DNA replication
2. Mutations arising from a failure to repair DNA damage |
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Nucleotide Substitutions
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-Point Mutation
-Most common type (70%) -Most occur during DNA replication -Can occur in exons and introns |
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Four Types of Point Mutations
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-Silent
-Missense -Nonsense -RNA splicing -Regulatory |
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Missense Mutations
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-Alters the 'sense' of the coding strand of the gene by coding for a different amino acid
-Most Common Point Mutation -50% of disease causing mutations |
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Nonsense Mutations
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-Mutation that creates a termination codon (premature stop codon)
-12% of disease causing mutations -Loss of function due to degradation of mRNA |
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RNA Splicing Mutations
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-Interrupts the acceptor/donor sites (GT(GU)/AG) between introns/exons
-10% of disease causing mutations -Often lead to Frameshift mutations or premature stop codons. |
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Transition Mutations vs.
Transversion Mutations |
-One purine for the other or one pyrimidine for the other
-The replacement of a purine for a pyrimidine, or vice versa -63% vs. 37% -Evidence of nonrandom mutations |
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Regulatory Mutations
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-Affect transcription factor binding, transcriptional control, or other aspects of gene regulation
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Frameshift Mutation
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-not a multiple of 3 and occurs in a coding sequence
-different sequence of amino acids generated |
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Large Deletions/ Insertions
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-6% of disease causing mutations
-Many are caused by mispairing of like sequences -DMD, CMT1A-dup, HNPP-del, and alpha thall |
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Partial Gene Duplication
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-May result in premature stop codon, Loss of function, or expression
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Whole Gene Duplication
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-May have an effect due to increased gene dosage
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Large Insertions
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Retrotransposition
-mutation by insertion of repetitive elements from mRNA and put back into DNA -Factor 8 gene in exon 14 (de novo) -NF1, Hemophilia, Factor 9 |
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Inversion
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Intrachromosomal recombination
-Seen in most inherited Hem A (Factor 8) cases -300:1 male predominance in origin -Hunter syndrome (13%) |
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Trinucleotide Repeat Mutations
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-Characterized by the expansion, within the affected gene, of a segment of DNA that contains a repeat of 3 nucleotides.
-As the gene is passed, repeats increase |
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Dynamic Mutation
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-Trinucleotide Repeat Mutation
-Altered gene expression or altered protein stability/function |
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Repeat Expansion Mutation
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-Fragile X (maternal origin)
-Huntingtons Disease -Progressive Myoclonus Epilepsy -Myotonic dystrophy 2 |
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Loss of Function
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-Reduction in protein dosage (alpha-thal)
-Missense -Deletions -Chromosome loss |
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Gain of Function
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Coding Region Mutations
-Increase ability of a protein to perform -Missense (Achondroplasia) Regulatory Region Mutations -Increase dosage (duplications, trisomies) |
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Mitochondrial Mutations
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-Maternal Inheritance
-mtDNA mutates 10x nuclear DNA -many neuromuscular diseases |
