genetics test 2 ch5 epigenetics

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doncheto
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286983
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genetics test 2 ch5 epigenetics
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2014-11-11 16:03:26
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Genetics Epigenetics
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Epigenetics
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  1. Exceptions to Mendel's prediction.
    • -Genotype of indivdual. --X-- phenotype
    • - Genes are not found with the nucleus.
  2. Epigenetic Inheritance
    Patterns of inheritance that does not involve the actual DNA (base pairs)

    DNA, chromatin (histone): modifications -- Do not stay from parents to child, last a life time.

    • Examples = -CH3 (methylation) - Histones
    •                                             - Nucleic Acids
    •                   -COCH3 acetylations
    •                   -Ubiquitin (small protein)
  3. Dosage Compensation
    • - Takes on diff form depending on the species.
    • diploid: xx xy
    • y- contains hardly any genes.
    • x- contains about 1000 genes.
    • Takes on diff form depending on the species.
  4. Dosage compensation in Marsupials
  5. 1st evidence of X-Activation
    • *Cytogenic - stain DNA
  6. Heterochromatin
    Tightly packed, very condensed DNA
  7. Euchromatin
    • shown as lighter,less stained
    • loosely packaged 
    •  -greater gene expression
    •  -more genes in general
  8. Barr body
    - tightly wound X-chromasome
  9. Molecular Mechanism of X-inactivation
    * Which X is silenced is random
  10. Occurs in 3 stages: X ist expressed
    @ Early stages of development (~30 cells)

    • 1. Initiation: one X is chosen
    • (targeted for silencing)
    • * It might be Xce ----> lots of genetic variation here

    2. Spreading: As embryo is developing, compacting of chromatin begin at Xic, then moves along chromosome.

    3. Maintenance:Through adulthood, each mitotic divisio, same x-chromosome (Barr body) is copied as such

    * Barr Body *Some genes escape inactivation (example x-ist)
  11. Phenotypic Result: example - Cats
    • * Female Calico Cats
    • * Patches of color
    • B = orange b = black
    • o = barr body
    • XBXB = orange ---Xinactivation--> XBo
    • XbXb = black ---Xinactivation--> Xbo
    • XBXb = orange ---Xinactivation--> XBo}patchs
    •                       ---Xinactivation--> Xbo}patchs
    • xxy = male calico
  12. Genetic Imprinting
    • * Methyl groups ---> on DNA
    •  
    •  -affects expression
    •    -the marks distinquishes between maternal and paternal inherited chromosomes/alleles
    •    ->->-> mono-allele expression 
    • *Only a dew human genes are imprinted
    • *No change in DNA sequence
    • ******Insert Diagram***********
    • More CH3 in general = silent gene
    • less CH3  = actively/expressed gene
    • * promoting proteins that inhibit trxn (transcription)
    • * Prevent binding of proteins that allow/enhance trxn 
    • * Near imprinted gene = Imprinting control region
  13. EX 1 genetic imprinting
    • **check powerpoint for result***
  14. Ex 2 genetic imprinting
    • genotypically = Tt
    • phenotype = appears as tt
    • or a a dominant trait
  15. Mitochondrial Inheritance
    Extranuclear/cytoplasmic inheritance

    mitochondrial/chloroplastic genomes

    • 1. Circular chromosome
    • 2. Double stranded
    • 3. serial copies -by size and # variation depending on species.

    • Genes
    • 1. mt n13 genes encode protein for mitochondria function
    • 2. tRNA, rRNAs 
    •   -necessary to translate genes
    •  Chloroplast = similar , but bigger 10x

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