Chapter 28 Study Guide
What cells form at the completion of meiosis II? Are those cells haploid or diploid?
(1) Mature Ovum - Fertilized (2n) diploid cells (2) Second polar body - degenerates (doesn't finish meiosis II)
What will happen to the cells produced as a result of mitosis during oogenesis?
(1) Oogonium (2n) - Remains as stem cell to divide again (2) Primary oocyte (2n) - Cells undergo meiosis to reduce number of chromosomes
What type(s) of cells are produced in meiosis I completion (female)? Are those cells haploid or diploid?
(1) Secondary oocyte (haploid - n) - Undergoes meiosis II (split pairs) and each has 23 pairs of chromatids (2) 1st Polar Body - Eventually degenerates (does not finish meiosis)
oogonium
(2n), diploid stem cells that gives rise to oocytes
How has the number of oocytes changed by the onset of puberty?
- By the onset of puberty, # of primary oocytes has been reduced between 80,000 & 400,000 (atresia)
Understand the basic process of spermiogenesis
- Cells elongate and shed excess cytoplasm - Acrosome and flagellum develop
Upon completion of meiosis I, what types of cells are produced? Are they haploid or diploid?
- Daughter cells are secondary spermatocytes (haploid - n) - Each has pairs of chromatids (split pairs in meiosis II)
When will meiosis I begin again in females?
- Each month a primary oocyte is activated => completes meiosis I - By the onset of puberty, # of primary oocytes has been reduced
When does meiosis I begin in females?
- Meiosis I occurs between 3 - 7 months gestation in females
What triggers meiosis II to begin? At what point will it pause?
- Ovulation or fertilization of oocyte triggers the beginning of Meiosis II. - It will pause during metaphase II
At what point does this meiosis I pause in females?
- Primary oocytes begins meiosis I but pauses @ prophase I - Remains paused until the onset of puberty
What type of cell is produced during meiosis II during spermatogenesis?
- Spermatids produced and mature during spermiogenesis
What 3 processes occur during spermatogenesis?
1. Mitosis of spermatogonia 2. Meiosis (produces spermatids/immature sperm) 3. Spermiogenesis (maturation of sperm)
What is produced as a result of mitosis during spermatogenesis? Are those cells haploid or diploid?
2 (2n) daughter cells: (1) Spermatogonium - Remain as stem cells, divide again (2) Primary spermatocyte - Enters meiosis I
Approximately how many primary oocytes will be present at birth?
2 - 4 million primary oocytes present at birth
What type(s) of cells are produced as a result of mitosis during oogenesis?
2 daughter cells: (1) Oogonium (2n) (2) Primary oocyte (2n)
What does the head of the sperm contain?
Chromosomes
Acrosome
Contains enzymes that helps the sperm to penetrate oocyte during fertilization
Why is the middle piece of the sperm important?
Contains mitochondria that produces the ATP to power the tail/flagellum
spermatogonium
Diploid cell (2n) undergoing mitosis to form more spermatogonium; triggered to undergo meiosis to form sperm
at the end of mitosis, are the cells produced haploid or diploid?
Diploid to diploid (2n --> 2n)
When does meiosis II begin in females?
Each month, one secondary oocyte begins meiosis II during ovulation point
Gametogenesis
Formation of gametes (sperm and egg/oocyte)
Spermatogenesis
Formation of sperm
During the oogenesis process, when does mitosis occur?
In females, all mitotic divisions that produce oocytes will occur PRIOR to birth
Does gamete formation involve mitosis or meiosis?
Meiosis
When does meiosis II finish?
Meiosis II will not complete until ovulation or fertilization of oocyte occurs.
Are oogonia haploid or diploid?
diploid
is a spermatogonium haploid or diploid
diploid (2n)
Oogenesis
formation of oocytes
Endometrium
inner lining of the uterus