chapter 51 Flashcards
What is sexual reproduction?
The production of a new individual by joining two parents’ gametes (haploid reproductive cells)
what is asexual reproduction?
-Offspring are produced from a single parent
-Offspring are genetically identical to the parent
what are 3 forms of asexual reproduction?
Budding, Regeneration, Parthenogenesis
what is budding?
Portion of parent pinches off to form complete new individual
what is regeneration?
Complete organism formed from a fragment of parent’s body
what is Parthenogenesis?
-Development of offspring from unfertilized eggs
-Some animals can reproduce sexually or parthenogentically
where are gametes formed ?
in Gonads
What results in spermatogonia and oogonia?(2n)
When germ cells multiple by mitosis
these are gametes.
What happens to Spermatogonia ?
multiple again by mitosis to produce primary spermatocytes and primary oocytes
What happens after production primary spermatocytes and primary oocytes?
they undergo meiosis I and II to form haploid gametes
what is Spermatogenesis ?
the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testes.
what occurs during Spermatogenesis?
-Primary spermatocytes undergo meiosis I to produce 2 haploid secondary spermatocytes
-Undergo meiosis II to produce 4 haploid spermatids
-Eventually develop into sperm
-One cell becomes four gametes
Sperm has head (with acrosome), midpiece, and tail
what is oogenesis ?
in the human female reproductive system, growth process in which the primary egg cell (or ovum) becomes a mature ovum.
what is male genitalia ?
consists of penis and scrotum
what is the scrotum?
holds testes where sperm develop at a temperature 2 celsius lower than core body temperature
what is the site of spermatogenesis ?
composed of seminiferous tubules.
what are testes composed of ?
seminiferous tubules (site of spermatogenesis) and Leydig cells (endocrine cells that secrete testosterone)
What is female genitalia?
Labia majora – same tissue as scrotum
Labia minora – same tissue as urethral primordial tissue
Clitoris – same erectile tissue as penis
External opening leads to vagina, cervix, and into uterus
Uterus has inner glandular lining (endometrium) and outer muscular layer (myometrium)
Pregnancy and Birth in Mammals
Called gestation.
-pregnancy begins when the embryo is established in the uterine lining
what are mammalian pregnancy types ?
Monotremes- lay eggs
Marsupials- young must complete development in the pouch, where nourishment is provided
-Eutherian mammals-retain their young for a prolonged period and nourish young via placenta
why are 5 to 10% of US adults infertile?
-due to sexually transmitted diseases
-malnutrition
-stress
-developmental disorders
Contraception
-blocks fertilization or implantation of egg
-vasectomy and tubal ligation prevent the transport
what is the proper order of of events in embryonic development?
fertilization, cleavage, gastrulation, neurulation, organogenesis
what is the stage of development that involves cell division without cell growth ?
cleavage
