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16 Cards in this Set
- Front
- Back
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define primary and secondary sexual dimorphism
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primary - differences in male/female gametes
secondary - differences in external reproductive or non-reproductive organs |
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what are the 2 types of organisms
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separate male/female (unisexual, dioecious)
both male/female parts (bisexual, monoecious, hermaphroditic) |
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what are distinguishable about chlamydomonas, Maize, and C. elegans
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chlamy - isogametes (non-distinguishable male/female gametes); haploid most of life then diploid for reproduction
Maize - distinguishable male/female gametes; 1/4 female megaspores survive meiosis C. elegans - hermaphroditic (XX) or male (XO); selfing creates 99% herm, 1% male; cross creates 1:1 ratio |
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what is the SRY region on a Y chromosome
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sex-determining region; controls male sex development
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what is the euchromatin region of the Y chromosome
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active DNA (many genes)
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what is the heterochromatin region of the Y chromosome
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inactive DNA (almost no genes)
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what is the MSY region
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contains SRY, euchromatin, and heterochromatin
-male specific region |
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what are the primary and secondary human sex ratios
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primary: male:females conceived
secondary: male:female born |
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why are more males conceived than females
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smaller, more motile Y chromosome in males
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what is Lyon's hypothesis
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in embryonic development, X-chromosomes are randomly inactivated
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what are barr bodies; what occurs in subsequent generations
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inactivated X-chromosome
-same chromosome remains inactive (imprinting) |
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what is the significance of Xic in a Barr Body
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(X inactivating center)
expressed only in barr bodies |
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what are the 3 types of pairings/inactivations
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1. XX pairing (normal)
2. no XX pairing (chaotic: both, one, or neither inactive) 3. block of pairing (no inactivation) |
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what matters in sex-determination in drosophila? how is chromosome dosage compensated
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-X:A = 1:1 female
-X:A = 1:2 male -MSL increases gene expression in male X chromosome |
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define hypertranscription, x-inactivation, hypotranscription
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hyper: increased male X gene expression (drosophila
x-inactive: (mammals) hypo: decreased female X gene expression (C. elegans) |
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what occurs in drosophila mosaics
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one X-chromosome is lost during first mitotic division
-left is XO (male), right is XX (female) |
