Animal Reproduction

Updated 2007-05-23 23:10


Question Answer
Asexual reproductionoffspring clones that are genetically identical to parent
How do cells in parent divide in asexual reproduction?Mitosis (division of cells not forming gametes)
Buddingoffspring begins to form within or on parent and completed when offspring breaks free and grows on its own.
One example of budding animalhydra
Fissionan individual splits into two or more descendents.
One example of fission animalflatworms
Parthenogenesiseggs produced by mitosis (offspring develops by unfertilized eggs)
One example of parthenogenesis animalwestern whiptail lizard
When is it more favorable to reproduce sexually?In an unstable, unfavorable environment, high density (easier to find mate)
When is it more favorable to reproduce asexually?In a stable, favorable environment, low density population (harder to find a mate) why ruin a good thing?
Sexual reproductionoffspring that are genetically distinct from both parents (involves meiosis-genetic recombination and differences)
One example of animal that can reproduce both asexually and sexuallydaphnia where sexual reproduction is more common in crowded pop than sparse pop
Gametogenesis-the mitotic and meiotic cell divisions and developmental events that result in the production of male and female gametes
Spermatogenesis-formation of sperm
Oogenesis-formation of eggs
Where does gemetogenesis occur in most animals?Gonads (a sex organ)
Where does gametogenesis occur in males?Testes in the seminiferous tubules
Where does gametogenesis occur in females?Ovaries
First stage of spermatogenesis-spermatogonia which are diploid stem cells
Second stage of spermatogenesismitosis which divides the cell to undergo meiosis (diploid)
Third stage of spermatogenesisprimary spermatocytes which are products of mitosis and are diploid
Fourth stage of spermatogenesismeiosis I which leads to secondary spermatocytes that then undergo meiosis II
Fifth stage of spermatogenesis4 spermatids for each spermatogonia which are haploid cells that get dumped into the lumen
Sixth stage of spermatogenesisthe spermatids mature into spermatozoa (mature sperm)


Question Answer
First stage of oogenesisoogonium which are diploid stem cells
Second stage of oogenesismitosis which divides cell to undergo meiosis (diploid)
Third stage of oogenesisprimary oocyte which is diploid
Fourth stage of oogenesismeiosis I which leads to formation of secondary oocyte and a polar body with uneven balance of cytoplasm.(haploid) which then undergoes meiosis II
Fifth stage of oogenesisootid and polar body which are haploid
Sixth stage of oogenesisone ovum
What happens to the polar body in oogenesis and why?It disintegrates because it only has a little bit of cytoplasm
What is evident in the size of an ovum?It is very large and has a lot of cytoplasm
What’s the main difference between spermatogenesis and oogenesis?Spermatogenesis creates 4 spermatozoa while oogenesis only creates one ovum
Why can’t boys make sperm until they hit puberty?Testosterone is needed for the process
When are primary oocytes made in women?Before birth which means that all females have all their primary oocytes before theyre born and once a month one starts developing
When do men stop making sperm?Not until death
When do women stop making ovum?Menopause


Question Answer
What is hypothesized about how animals that cannot see their mates time the release of their gametes?Phermones might synchronize gamete release an example of this is when roommates or girls that spend a lot of time together start their cycles around the same time
External fertilization-mostly in aquatic animals that release many many eggs and sperm into the environment.
What does research indicate about when gemetogenesis occurs?In response to environment or favorable breeding season
Internal fertilization-in many terrestrial animals and some aquatic animals (through copulatin)
Copulation-deposit sperm directly into the female reproductive tract with aid of copulatory organ - penis
Spermatophorepackage of sperm
Australian redback spider sex-suicidal males backflip into mouth of female probably because this makes for longer copulation because it doesn’t stop until the meal is over and so fertilization of more eggs is possible
Banana slug sex-theyre hermaphrodites with both male and female parts, during copulation one eats off the others penis
California newt sex-males don’t copulate but lay a spermatophore on the floor where the female then sits on and picks it up with her cloaca (internal fertilization)
Cloaca- a chamber used for both reproduction and excretory system which opens to the environment
Cloacal kiss-swans don’t have copulation organ, so their cloaca kiss and the male ejaculates of the females back and semen goes into her
Monogamy-one male only or one mate at a time (no monogamous animals)
Polygamy-more than one partner at a time. Birds are the most polygamous
Extra pair copulations (EPCs) –form a pair but copulate with others
Oviparity-lay eggs and embryo develops in external environment (birds, fish,amphibians,reptiles) some species let egg fend for themselves while others take care of them
Viviparity-live birth where embryonic development takes place in mothers body (mammals)
How did scientists understand how viviparity and oviparity evolved?Phylogenetic tree
What happened with the sceloporus lizards?They evolved viviparity independenly in two spots
Why were there two places where oviparity evolved into viviparity?Viviparity should evolve with cold temperatures because they can keep egg warm in the body.
What happens to the developing embryo in cold temperatures?Higher percent of deformities and develop slower
Male reproductive structures' 3 basic components1.spermatogenesis and sperm storage 2.prouction of additional fluids and 3.transport and delivery
Where are sperm produced?testes
where are sperm stored?epididymis
seminal vesicles-contains fructose and functions as a source of chemical energy for sperm movement and stimulates mooth muscle contractions in uterus
prostate gland-contains antibiotic compound which prevents urinary tract infections in males as well as citric acid that is a nutrient to sperm
bulbourethral gland-contains alkaline mucous that lubricates the tip of the penis and neutralizes acids in urethra (pre-ejaculate)
the bulbourethral gland, prostate gland and seminal vesicles make upaccessory fluids which are added to sperm prior to ejaculation
ejaculation-expulsion of sperm from the body
semen-the combination of sperm and accessory fluids
vas deferens-pair of muscular tubes that transports semen from the epididymis to the ejaculatory duct
urethra-longer tube that passes through the penis and services both the reproductive and urinary systems in males.
baculum-bone inside penis which helps stiffen penis during copulation (in rodents but not humans)
labia majus(bottom)/labia minus(top)-opening of the urethra and vagina
clitoris-sensitive organ that develops in the same population of embryonic cells that give rise to penis
what is different in the urethral openings of a male and female?male has one opening for both reproduction and urinary purposes while females have two
vagina-birth canal where semen is deposited and where embryo is delivered
two functions of female reproduction system1.production and transport of eggs 2.development of offspring
where are eggs produced?ovaries
oviduct-tube where fertilization may take place
uterus-muscular sac
what happens during ovulation?a developing oocyte is expelled from ovary and enters oviduct. Fertilized eggs are then taken to the uterus
where does embryonic development take place?uterus
cervix-necklike opening of the uterus where the developed embryo passes through during childbirth
endometrium-highly vascularized inner lining of uterus where placenta forms
testosterone-male sex hormone
estradiol-female sex hormone which belongs to a class of hormones known as estrogen
Both testosterone and estradiol are what?steriods, both bind to receptors inside the nucleus of target cells and that the resulting hormone-receptor complexes bind to DNA and trigger changes in gene expression.
Where is testosterone synthesized?in specialized cells inside the testes
Where does estraiol synthesized?in the overies
follicle-cells that surround each developing egg where sex hormones are produced
what three events do the human sex hormones play a key role in?1.the development of the reproductive tract in embryos 2.the maturation of the reproductive tract during the transition from childhood to adulthood 3.the regulation of spermatogenesis and oogenesis in adults
puberty-the process that leads to sexual maturation in humans
how is puberty triggered?increased levels of testosterone and estrogen
gonadotropin-releasing hormone (GnRH)-hormone from hypothalamus
boys and girls who are entering puberty experience distinctive pulses in the concentration to these two pituitary hormones.lutenizing hormone (LH) and follicle-stimulating hormone (FSH) in pituitary glands secreted into blood stream
What was the hypothesis about the involvement of the hypothalamus and pituitary glands in regulating sex hormones?pulses in LH and FSH occurred in response to the release of GnRH and were responsible for testosterone and estrogen increase that leads to target tissues breasts in females and layrnx in males
What did scientists do to test the hypothesis about the involv. w/ hypothalamus and pituitary glands in regulating sex hormones?They took boys and girls that had a defecit in their hypothalamus causing a postponing effect on puberty and they treated these people with GnRH which made puberty start for these individuals
What triggers GnRH increases at the right age?some evidence that nutrition plays a key role...larger girls tend to undergo puberty faster than thin girls...malnutrition and extreme exercise also make puberty delay
two factors that lower age of puberty.hormones getting into the environment,birth control metabolites in urine, pesticides with estrogen
do sex hormones undergo negative feedback?yes
menstural cycle-a monthy reproduction cycle that occurs in the ovaries about every 28 days on average
menstration-the expulsion of the uterine lining
first phase in menstral cyclefollicular phase-where follicle matures and lasts 14 days
what stimulates the follicle growth?FSH
what stimulates follicle cells to secrete estrogen?LH
what happens after the follicular phase in the menstral cycle?ovulation occurs and releases its secondary oocyte into the oviduct
second stage in menstral cycleluteal phase which is the formation and degeneration of the corpus luteum
corpus luteum-"yellowish body" from the ruptured follicle
What are events in the menstrual cycle regulated by?Pituitary and ovarian hormones
In the gonadotropic hormone cycle graph what suggests that LH might trigger ovulation?LH levels are pretty constant except for a spike just prior to ovulation
What are the patterns in FSH concentrations in the ovarian cycle?FSH concentrations are high during the follicular phase and low during the luteal phase yet also make a small spike before ovulation
What are the patterns in progesterone levels in the ovarian hormone cycle and what does this suggest?Progesterone is low during follicular phase and high during the luteal phase suggesting it might support maturation of the thickened uterine lining to provide for embryo
What are the patterns in estradiol levels in the ovarian hormone cycle?The change in a complex way
What does the corpus luteum secrete?Progesterone
What is menstration?If the corpus luteum degenerates progesterone levels drop and endometrium is shed
What effect does estradiol levels have on regulartory hormones like LH and FSH?High levels increase the release of regulatory hormones while low levels suppress it
What do progesterone injections do to regulatory hormones?Inhibit both FSH and LH
Birth control is this.Low levels of estradiol
What type of feedback is in the follicular phase?Negative because low levels of estradiol suppresses secretion of LH
What type of feedback is in ovulation?Positive feedback because large quantities of estradiol trigger high levels of LH and FSH
What type of feedback is in luteal phase?Negative because high levels of progesterone inhibit LH and FSH
How long are oocytes viable after ovulation?Less than 24 hrs
How long is sperm viable for?5 days
To get pregnant what needs to happen?Intercourse has to occur less than 5 days prior to ovulation
Ascrosomal reaction-enzymes release in head of sperm to chew path through oocyte membrane
Gestation-full period of development
Human chorionic gonadotropin (hCG)-chemical messenger that prevents the corpus luteum from degenerating and is used to detect pregnancy
First trimester-endoderm ectoderm and mesoderm form and differentiate into organs and systems, heart pumps blood, amniotic fluid made to protect embryo, placenta forms for nutrients,nervous system too!
Second and third trimesters are good for.Growth
How does mother nourish the fetus?Body changes increases cardiac output, breathing rate and volume increase,higher gas exchange,
Fetal alcohol syndome (FAS)-children who are at risk of hyperactivity severe learning disabilities and depression because of drinking mothers
Why does alcohol do to fetus and how did they test this?It kills the neurons in the developing brain and they showed this by taking rats and injecting some with ethanol
Birthing sequence-1.dilation of cervix 2.expultion: delivery of infant 3. Delivery of placenta