the creatin of offspring without the fusion of egg and sperm. results in offspring that are genetically identical to one another and to their parents. mechanisms are: budding, fission, parthenogenesis.
asexual reproduction where offspring begin to form within or on a parent by fragmentation. process is completed when offspring breaks free and begins to grow on its own
asexual reproduction where an individual simply splits into two or more descendants
asexual reproduction where offspring develop from unfertilized eggs, which are identical to the mother
sexual females have half as many daughters as asexual females.
how many daughters does a sexual female have in comparison to asexual. this is called the "twofold cost" of sexual reproduction. still, most eukaryotes replicate this way
sexual reproduction: gametogenesis, fertilization(including mating). gene reshuffling mechanisms: ind. assort. of chromosomes, crossing over, random fert.
depends on meiotic cell division, consists of two fundamental steps (which are?) contributes to genetic variation within a species by reshuffling existing versions of genes using three mechanisms (which are?)
4 haploid daughter cells with half as many chromosomes as the parent cell are reproduced in diploid org. (vs 2 diploid daughter cells in mitosis). two divisions occur: meiosis I and II, preceded by interphase. includes chromosomal exchange via 'crossing over'
collectively, the mitotic cell divisons, meiotic cell divisions and developmental events that result in product of male (sperm) and female (egg) gametes. includes spermatogenesis, oogenesis
formatin of the sperm. part of gametogenesis. when spermatogonia divide by mitosis, they form these. these then undergo meiosis to form _________ which undergo meiosis II which results in four haploid cells called _______ which then mature into ______. process continues
formation of the egg. diploid cells called____ divide by mitosis to form ________. the production of the last step stops early in development in many mammals (before birth in humans). when these cells undergo meiosis, only one of the our haploid products (known as ________) matures into an egg. the other cells (called _______) do not mature into egg
sex organ. male version is testes and female version is ovaries. in the vast majority of animals, gametogensis occurs here.
male gonads. diploid cells here called spermatogonia. highly coiled tubes surrounded by connective tissue. held outside abd cavity in the scrotum where the temp is lower than the abd cavity
diploid cells int he male gonads that divide by mitosis (forming primary spermatocytes) to generate the cells that undergo meiosis (producing secondary spermatocytes) which then undergo meiosis II.
when spermatogonia divide by mitosis, they form these. these then undergo meiosis to form _________ which undergo meiosis II which results in four haploid cells called _______ which then mature into ______. process continues
product of meiosis, three out of four divisions of the oocytes do not become an egg, but they become this.
pairing of the opposite sex (dioecious) or hermaphroditic (monoecious) organisms for copulation
oppsite sex organism
male and female at the same time (ex earthworm)
may function as a male or female at different times (ex anemone fish)
union of sex organs of two sexually reproducing animals for insemination (deliberate introduction of male reproductive cells into female reproductive organs) and subsequent internal fertilization
the union of egga and sperm creates this single diploid cell which will develop into an embryo
eggs shed by female are fertilized by sperm in the external enviro
sperm are depositited in or near the female reproductive tract (which requires behavioral interactins and compatible copulatory organs) and fertilization occurs within the tract
fertilization: six steps
fertilization. six steps
1. recog of sperm and egg
2. activation of sperm, enabling it to access plasma membrane of egg (ACROSOMAL PROCESS)
3. plasma mem of egg fuses w/ plasma mem single sperm
4. egg blocks other sperm (CORTICAL REACTION)
5. egg metabolically activated to start dev.
6. egg/sperm nuclei fuse. creates diploid nucleus of zygote
sexual reproduction results in this. potential advantages: increased repro success of parents in changing enviro, increase rate of adaptation, shuffling of genes and elimination of harmful ones. based on ind assort of chromos, crossing over, and random fert
independent assortment of chromosomes
random orientation of homologous pairs of chromosomes in metaphase I. results in 50% change of particular daugher cell of meisos I getting a maternal/paternal chromosome from a particular homologous pair. 2n possible chromosome combinations in gametes.
produces recombinant chromosomes that carry alleles from both parents and increase the genetic variability of gametes. produces chiasmata that hold homologous chromosomes together.
defined by the number of possible combinations in zygote = (# of possible combinations in gametes)^2 = 2^n * 2^n= 2^2n
female external reproductive anatomy
two sets of labia (minora and majora), clitoris, vagina
labia (minora and majora)
two sets of this, folds of skin that cover the urethral and vaginal openings.
sensitive organ that develops from the same embryonic cells that give rise to the penis in males. has a head called a GLANS covered by the PREPUCE
chamber where semen is deposited during sexual intercourse and through which a baby is delivered during childbirth
internal female repro sysem
has two functions, production and transport of eggs and development of offspring
production and transport of eggs
note: eggs are produced in the paired ovaries. during ovulation, egg is expelled from ovary and enters oviduct (FALLOPIAN TUBES) where fertilization takes place. fertilized eggs are then transported to uterus.
development of offspring
embryonic development takes place in uterus. developed fetus passes through its opening, the cervix, and into vagina during childbirth
contained in the ovaries, consist of partially developed egg, called an oocyte, surrounded by support cells
partially developed egg contains in the follicles of the ovary. once a month, it develops into an ovum by the process of oogenesis
oocyte developes into an egg whcih is then released into oviduct (FALLOPIAN TUBES) where it can be fertilized
when the ovary released a fertilized egg into the fallopian tube
where the ovary releases the egg to during ovulation so it can be fertilized
aka, the fallopian tubes. the egg travels from the ovary to the uterus via this path. cilia here help convey egg to uterus
organ that holds embryo/fetus as it develops. lined with endometrium which has many blood vessels. narrows at the cervix, which opens into the vagina
called "mouth of the womb", the narrow end of the uterus that opens into the vagina
thin walled chamber that is the repository for sperm during copulation and serves as birth canal. opens to outside at vulva
outside of the vagina, consists of labia majora/minora and clitoris.
head of the clitoris, covered by the ______
spermatogensis and sperm storage, production of accesory fluids, transport and delivery
the reproductive system in human males has just three basic functional components which are?
stores the sperm that are produced in the testes
seminal vesicles, prostate gland, and bulbourethral gland are these. provide accesory fluids. semen is a combo of accesory fluid and sperm. accesory fluid varies widely among animals
combination of sperm and accesory fluid
tubes that transport sperm from epididymis to the EJACULATORY DUCT
Tube through which semen enters the male urethra
a longer tube that passes through the penis and services both the reproductive and urinay systems in males and is expelled during ejaculation
some species have this bone inside their penis. not present in humans.
Narrow, coiled tubules that produce sperm in the testes.
produce hormones and are scattered between the seminiferous tubules of the testes
sack that testes are held outside of the animal for lower temp
1. from seminiferous tubules of testis, sperm pass into coiled tubules of epididymis
2. during ejac, sperm propelled through muscular vas deferens
3. then ejaculatory duct
4. into urethra
5. exits penis
seminal vesicles (x2)
accesory gland that contribute about 60% of the total volume of semen
accesory gland that secretes its product directly into the urethra through several small ducts
accesory gland that secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra
composed of three cylinders of spongy erectile tissue. during arousal, tissue fills with blood causing erection. head ofpenis has thinnger skin covering than shaft, more sensitive to stimulation.
spermatogenesis vs oogenesis
1.all four products of meiosis develop into sperm, while only one of four becomes an egg
2.spermato occurs throughout adolescence and adulthood
3. sperm produced continously without prolonged interruptions like oogenesis
spermatogenesis: sperm dev. continous and prolific (millions per day). each 7 weeks to develop. small and motile to
oogenesis: dev of mature egg prolonged process. immature eggs form in female embryo, BUT do not complete dev until yrs or decades later. eggs, much larger than sperm, carry out fuction in female.
3 ways spermatogenesis differs from oogenesis?
hypothalamus, anterior pituitary, gonads
human reproduction is coordinated by hormones from what three places? hormones serve many functions in addition to gamete production, including sexual behavior and the development of primary and secondary sex characteristics
gonadotropin-releasing hormone (GnRH)
secreted by the hypothalamus and directs the release of FSH and LH from anterior pituitary
FSH and LH
regulate processes in the gonads and the production of sex hormones(such as estrogen in females)
remale reproduction cycles. NOTE
Note: hormone secretion/repro events are cyclic. prior to ovulation, endometrium thickens with blood vessels to prep for embryo implantation. if no implant, endo sheds (menstruation). two cycles female repro that hormons link 1, ovarian cycle, 2, menstrual cycle
changes in the ovaries started by release of GnRH, FSH, LH stimulating follicular phase ending at ovulation when secondary oocyte is released. then remaining follicular tissue forms CORPUS LUTEUM (LUTEAL PHASE) which disintegrates and ovarian steroid hormones decrease
follicle growth and an increase in the hormone estadiol. this phase ends at ovulation.
follows ovulation, third step of ovarian cycle. follicular tissue left behind transforms into the corpus luteum which disintegrates and ovarian steroid hormones decrease
1. thickening of endometrium during the proliferative phase (c. w/ follicular phase)
2. secretion of nutrients during secretory phase (c. w/ luteal phase)
3. shedding of endometrium during menstrual flow phase (c. w/ growth of new ovarian follicles)
new cycle begins if no embryo implants in endo
part of the menstrual cycle. thickening of the endometrium. coordinates with follicular phase
part of the menstrual cycle. secretin of nutrients. coordinates with luteal phase
menstrual flow phase
part of the menstrual cycle. shedding of the endometrium. coordinates with the growth of new ovarian follicles.
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