Biobases 2 Ch 10 Slides - Reproductive Behavior - REPRODUCTIVE BEHAVIOR Reproductive Behaviors Sexually dimorphic behaviors Courting Mating Parental

Biobases 2 Ch 10 Slides - Reproductive Behavior -...

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REPRODUCTIVE BEHAVIOR
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Reproductive Behaviors Sexually dimorphic behaviors: Courting Mating Parental behaviors Aggressive behaviors Behaviors are largely shaped by hormones during fetal development and after birth
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Sexual Development An individual’s sex is determined by their inherited chromosomes at ovum fertilization by the father Humans inherit 23 pairs of chromosomes23rdpair are the sex chromosomesXX and XYY chromosome is responsible for development of glands that produce male sex hormones
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Chromosomes
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Sex Organs Gonads – testes and ovaries Produce ova/ sperm and secrete hormones Development controlled by Sry gene on Y chromosome Once developed, hormones continue sexual development via organizational & activational effects Internal sex organs Female – fimbriae, fallopian tubes, uterus, & inner 2/3 of vagina (together called Müllerian system) Does not require hormonal signal – develops automatically Male – epididymis, vas deferens, & seminal vesicles (called Wolffian system) Only develops if stimulated by hormones produced by testes Anti-Müllerian hormone – defeminizes Androgens – steroid hormones signal Wollfian system development & masculinize Testosterone & dihydrotestoserone (converted from testosterone)
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Internal Sex Organs Male Reproductive System
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Sex Organs During Fetal Development AMH +Androgens No AMH No Androgens
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Internal Sex Organs
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Genetic Disorders of Internal Sex Organs Androgen insensitivity disorder – insensitive to androgens Due to genetic mutation on X-chromosome Prevents formation of androgen receptors Develop female external genitalia without corresponding internal sex organs → XY woman Persistent Müllerian duct syndrome Due to failure in production of anti-Müllerian hormone or absence of hormone receptors In genetic males, masculinization occurs via androgens, but no de-feminization Individual has male & female sex organs
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Genetic Disorders of Internal Sex Organs Turner’s syndrome A genetic disorder due to loss of X chromosomal material that affects females primarily Associated with Dr. Henry Turner who described several cases in 1938 Characterized by abnormal physical features and cognitive, social, and behavioral deficits Prevalence 1: 2500 Heterogeneous disorder Ranges from mild to severe Develop into females with corresponding internal and external characteristics Lack gonads – no ovaries
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Form of TS Karyotype Frequency (%) Description Monosomy X Only 1 X Chromosome 45, X 45 – 50 2/3 maternally derived; occurs during meiosis before fertilization Mosaicism 45, X/ 46, XX or 45, X/ 46, XY, 47, XXX 30 Occurs early in mitotic cell division; almost all are female Isochromosome 2 short X arms or 2 long arms (arms are identical) 46, isoXᵐ or 46, isoXᵖ 10 Occurs during anaphase when chromosome strand divides transverse direction, not axially Deletions, rearrangements, and translocations 10 Abnormality during meiotic division Ring X Centromere region of X missing ring formation 2 - 5 Loss of centromere causing ring to form Characterization of TS Etiologies
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