5 6 2014 CHAPTER 50 Animal Reproduction PPT Notes reproductive systems variable species btwn asexual sexual reproduction o male reproductive system structures produce store sperm synthesize semen o female reproductive system structure produce eggs receive sperm care for embryo hormones from pituitary gland female reproductive organs regulate menstrual cycle hormones interact via positive negative feedback asexual reproduction mitosis offspring genetically identical to one another parent cloning o 3 mechanisms of asexual reproduction budding offspring forms in or on parents breaks away when formed ex hydra fission individual splits into 2 organisms ex anemones parthenogenesis female produces offspring w o fertilization from male ex lizards offspring genetically identical eggs produced via mitosis or meiosis sexual reproduction meiosis offspring genetically different to one another offspring genetic recombination during meiosis fusion of haploid gametes gametogenesis mitotic meiotic cell divisions developmental events result in production of female male gametes occurs in gonad sex organ testes or ovaries oogenesis formation of eggs spermatogenesis formation of sperm occurs continuously throughout male life spermatogonia occurs in male gonad diploid cells that divide by mitosis to generate cells that undergo meiosis process primary spermatocytes produced by spermatogonia PS undergo meiosis I produce 2 secondary spermatocytes SS secondary spermatocytes undergo meiosis II ultimately produce 4 haploid cells spermatids which mature into sperm o o o o o o oogenesis formation of eggs stops early in development in many mammals stops before birth in humans oogonia occurs in female gonad diploid cells that divide by mitosis to generate cells that undergo meiosis process primary oocytes produced by oogonia PO undergo meiosis only one of 4 haploid products ovum matures into egg polar bodies 3 haploid products that do not mature into egg zygote formed through the fertilization of a sperm egg diploid egg carries genetic material from female contains nutrients needed by embryo during early growth o o yolk in cell nutrient source made of protein fats vitelline envelope located outside cell membrane protects egg zona pellucida name of envelope in humans in sea animals eggs surrounded by jelly coat o o o o o o o o o o o 5 6 2014 sperm mammalian sperm specialized for motility fusing w egg cell structure head nucleus acrosome enzyme for penetrating egg neck contains one centriole combine w centriole contributed by egg centrioles form spindle during mitosis o midpiece contains mitochondria supply ATP that powers sperm to swim to egg o tail flagellum used to swim sperm competition competition btwn sperm from different males to fertilize eggs of same female experiment Geoff Parker w dung flies two males mate w single female last male to copulate fathered majority of offspring produced confirmed second male advantage is widespread second male to copulate more likely to father offspring second male s sperm physically dislodged replaced first male s gametes from female sperm storage area fluid accompanying sperm during fertilization displaces stored sperm from competing males fertilization o external fertilization individuals release gametes into environment fertilization most animals rely on this live in aquatic environments produce s of gametes gametogenesis happens in response to environmental cues lengthening days warmer water temps favorable breeding season gametes released in response to specific cues from individuals of same species pheromones chemical messengers that may be involved in coordination of gamete release internal fertilization males deposit sperm into reproductive tracts of females occurs in majority of terrestrial animals a lot of aquatic animals 1 copulation males deposit sperm directly into female reproductive tract w aid of copulatory organ called the penis 2 spermatophore males package sperm into placed into female reproductive tract by male or female once fertilization has happened embryo laid as egg outside mother s body retained inside body oviparous species egg laid outside mother s body embryo develops in external environment mothers make large eggs containing all nutrients fluids embryo needs to develop until hatching ovoviviparous species offspring develop inside mother s body but are nourished by yolk mothers make large eggs containing all nutrients fluids embryo needs to develop until hatching viviparous species egg stays in mother s body embryo develops receives nutrition from mother eggs are small have almost no nutrients embryo depends on mother for O2 chemical energy in form of sugars amino acids raw materials waste removal humans are viviparous vertebrates human male reproductive organs testes produces sperm via spermatogenesis epididymis stores sperm seminal vesicles prostate gland bulbourethral gland forms accessory fluids added to sperm before ejaculation semen combination of sperm accessory fluids expelled during ejaculation vas deferens tubes that transport sperm from epididymis to ejaculatory duct urethra tube that passes through the penis for both reproductive urinary systems in males baculum bone in penis not present in some species humans human female reproductive organs o mature egg cell usually membrane bound structure consisting of haploid nucleus organelles yolky nutrients o o ovary meiosis occurs egg cells ova produced external anatomy 5 6 2014 o functions labia minora labia majora skin folds that cover urethral vaginal openings clitoris a sensitive organ developed from the same embryonic cells that develop penis in males vagina chamber where semen is deposited during sexual intercourse baby hole egg production transport eggs produced in paired ovaries ovulation egg expelled from ovary enters oviduct fallopian tube for fertilization fertilized eggs uterus development of offspring embryonic development occurs in uterus cervix fetus passes through when developed goes into vagina sex hormones in mammalian reproduction testosterone male sex hormone o synthesized inside special cells within testes levels trigger puberty estradiol female sex hormone belongs to class of hormones called estrogens follicle structure that surrounds developing egg levels trigger puberty progesterone steroid hormone produced along w estrogens in ovaries roles of human sex hormones development of reproductive tract in embryos maturation of reproductive tract during transition from
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