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43 Cards in this Set
- Front
- Back
cohesin
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protein binding chromatids together
*mitosis: broken by separase *meiosis: allows for recombination; protected by shugoshin ("guardian spirit") at centromere |
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penetrance
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percentage of individuals with a particular genotype that express the associated phenotype
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hemizygous
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inability to be hetero or homozygous b/c individual possesses only one chromosome
*example: human males only have one x chromosome |
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Prophase 1
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5 substages:
leptotene zygotene (crossing over initiates) pachytene (synaptonemal complex) diplotene (chiasmata: point @ which crossing over occurs) diakinesis |
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Synapsis
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very close pairing association of homologous chromosomes
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Tetrad
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pair of synapsed chromosomes
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Metaphase 1
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tetrads align on plate; microtubules attach, one to a pair
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Prophase
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chromosomes condense and mitotic spindle forms
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Prometaphase
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nuclear envelope disintegrates, and spindle microtubules anchor to kinetochores
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Metaphase
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chromosomes align on the spindle-assembly checkpoint
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Anaphase
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sister chromatids separate, becoming individual chromosomes that migrate towards spindle poles
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Telophase
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chromosomes arrive at spindle poles, the nuclear envelop re-forms and the condensed chromosomes relax
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Cytokinesis
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cytoplasm divides; cell wall forms in plant cells
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Monoecious
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hermaphroditism “one house”
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Turner syndrome
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single x chromosome
sterile, short, broad chest, normal IQ |
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Klinefelter syndrome
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one y, multiple x
male, tall, reduced male characteristic |
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Qualitative traits (Discontinuous)
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analyzed using Mendelian crosses by placing each individual in a phenotypic class
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Quantitative traits (continuous)
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individuals vary in the quantity of the characteristic; no discrete phenotypic classes
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standard deviation
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normally distributed populations = describes shape of distribution
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correllation coefficient (r)
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measures the strength of the association b/t two traits
*line slope |
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phenotypic variance
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*genotypic variance
*environmental variance *interaction variance |
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High heritability
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Genetic differences cause much of the phenotypic variance
*VG / VP (genotypic variance divided by total phenotypic variance) |
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Incomplete (partial) dominance
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offspring falls between homozygotes
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Codominance
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Heterozygote shows both phenotypes
*common for traits with a molecular / biochemical phenotype *blood type is an example |
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Overdominance
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Heterozygote is more extreme than either homozygote
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Heterogametic sex
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Produces gametes with two sex chromosome genotypes
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Homogametic sex
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Produces gametes with one sex chromosome genotype
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Chromosome composition
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controls sex determination gene action.
X:A composition -> X:A ratio measuring genes activated -> Sex-specific genes activated |
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Sex determination genes
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control an individual’s sex
* Primary signal: one gene on the Y: SRY (sex determining region on the Y) produces TDF (testis determining factor). Response to the primary signal: Presence of TDF produces a male gonad. Absence of TDF produces a female gonad. Gonads produce sex determining hormones |
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Dosage compensation
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makes up for the imbalance of sex chromosomal influence (ex. barr bodies)
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Dihybrid Genotypic Ratio
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1:2:1:2:4:2:1:2:1
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dihybrid Phenotypic ratio (normal)
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9:3:3:1
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Lethal period
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time in which lethal alleles kill carrier
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Penetrance
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percentage of mutant individuals with mutant phenotypes
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Expressivity
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the severity of the phenotype
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Epistasis
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expression of one gene masks the expression of another gene
*ex: recessive h in human blood type _ _ hh = O antigen |
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Conditional alleles
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*Gene expression is affected by the external environment (ex. temperature sensitive)
*Gene expression is affected by other alleles in the “genetic background,” or the internal environment (ex. sex-limited, position effects) |
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Sex-limited
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The expression of some genes is different in males and females.
(ex. baldness) |
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Cytoplasmic inheritance
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The phenotype is controlled by genes in the cytoplasmic organelles (mitochondria and chloroplasts)
*test: backcross (should not produce male characteristic) |
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Maternal effect
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Gene products packaged in the egg by the mother determine offspring phenotype
*the maternal genotype determines the offspring phenotype, regardless of the offspring genotype. *only affects one generation |
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Infective inheritance
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The phenotype is controlled by infectious, cytoplasmic agents
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Genomic imprinting
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the allele from one parent is inactivated.
*paternal imprint: father's genes are not expressed |
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Viroids
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Small, circular nucleic acid molecules that do not code for any proteins.
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