Reproduction Notes from Old Notes Flashcards
Diploid cells
have 2 copies of each chromosome
Gametes
Haploid cells that fuse via process called syngamy to form a zygote (diploid cell)
Egg (ovum) - female gamete; big, non-motile
Sperm - male gamete; small, motile
Mitosis
Makes exact copy of itself
2n -> 2n
Phases of Mitosis
Prophase Metaphase Anaphase Telophase Cytokinesis
Interphase
Nuclear envelope intact
No chromosomes visible
Prophase
Nuclear membrane dissolves
Metaphase
Chromosomes align down center
Spindle forms
Anaphase
Spindle breaks centromere connection and sister chromatids move to opposite poles
Telophase
Chromosomes reached poles
Cytokinesis
Membrane forms around both cells
Meiosis
Reduction division; daughter cells are haploid, parental cell is diploid
Spermatogenesis
Creation of male gametes
The germ line cells that give rise to testes is called spermatogonia (2n)
Spermatogonia undergoes mitosis and gives rise to 2 diploid cells
One of these diploid cells is called a primary spermatocyte (2n), the spermatocyte will undergo meiosis I and form 2 haploid daughter cells called secondary spermatocytes (1n); they have 2 chromatid per chromosome
The other diploid cell is called a spermatogonia (2n). Spermatogonia will undergo mitosis again. The 2 secondary spermatocytes will undergo meiosis II and form a total of 4 haploid spermatid (1n)
Primary spermatocytes
When spermatogonia undergo mitosis and give rise to 2 diploid cells. One of the diploid cells is called a primary spermatocyte. The spermatocyte will undergo meiosis I and form 2 haploid daughter cells called secondary spermatocytes (1n). The 2 secondary spermatocytes will undergo meiosis II and form a total of 4 haploid spermatid.
Spermeogenesis
Maturation of the products of spermatogenesis, namely the spermatid into spermatozoa. Most of the cytoplasm has been reclaimed and recycled
Oogenesis
Creation of the female gametes
Oogonia (2n) are present in the women’s body before birth, originate in yolk sac and migrate down during development. They divide by mitosis to form 2 daughter cells. Both daughter cells are primary oocytes (2n). Both will undergo meiosis. The primary oocyte will undergo meiosis I and form secondary oocyte (1n w/ 2 chromatids) and a polar body. The polar body will atrophy and die. In meiosis I in females, there is unequal cytokinesis. The secondary oocyte undergoes meiosis II and form a haploid ovum (1n) and another polar body that is also discarded
What happens to the primary oocytes?
Both will undergo meiosis. The primary oocyte will undergo meiosis I and form secondary oocyte (1n w/ 2 chromatids) and a polar body. The polar body will atrophy and die. The secondary oocyte undergoes meiosis II and form a haploid ovum (1n) and another polar body that is also discarded
What happens to the secondary oocyte?
The secondary oocyte undergoes meiosis II and form a haploid ovum (1n) and another polar body that is also discarded
What happens to the polar body?
The polar body will atrophy and die
In females cytokinesis is equal or unequal?
Unequal
What is growth in embryo?
Growth is addition of material. There is no growth until implantation into uterine wall and placenta is formed