Gametogenesis Lab Report

     The process, during which the germ cells are generated is called meiosis. It represents nature's solution to the problem of chromosome doubling that would occur, if two diploid cells, i.e. two cells with a double set of chromosomes would fuse. Accordingly does meiosis produce haploid germ cells, with maternal and paternal germ cell fusing at fertilization and thus generating a

With sperm, each cell goes through meiosis to produce four sperm cells. During oogenesis a oogonium cell undergoes mitosis to produce primary oocytes. It differs from sperm formation because it is a stop-start process. It also divides the cell unequally and one primary oogonium cell produces one active cell in contrast to sperm.

Purpose: The purpose of this lab was to calculate the amount of time that was spent by a cell in each of the phases of mitosis. Also, it is used to be able to compare the process of mitosis between plant and animal cells.

Germ cells: the sexual reproductive cell at any stage from the primordial cell to the mature gamete

Meiosis results in four daughter cells (gametes) which have half the number of chromosomes of the original cell. They are therefore called haploid cell

A) Meiosis consists of two cell divisions and is broken up into Meiosis I and Meiosis II. At the beginning of the Cell Cycle, in this case there are four chromatids each from the homologous pairs being A, a, B, b. This is the Diploid number (4) meaning it is 2 times the haploid number that will be seen at the end of meiosis II. During the S phase of interphase, the chromatids replicate and reach the end of G2 phase. Now starting meiosis, during the first stage of prophase I the chromosomes condense and pair up through synapsis with their sister chromatids creating AA, aa, BB, bb. After they pair up they go through a process called crossing over, where the homologous chromosomes share a piece of their genetic material with each other. Crossing over allows for the genetic diversity of chromosomes. Now there are four homologous chromosomes Aa, Aa, Bb, Bb, each containing heterozygous alleles because the sister chromatids exchanged genetic information with their homologous pair. During late prophase I, spindle fibers being to form where they will later attach to a homologous chromosomes centromere. The next stage is Metaphase I. During metaphase I, the homologous pairs line up at the metaphase plate, also known to be the center of the cell. The homologous pairs form a tetrad which is considered a group of four homologous chromosomes. These homologous chromosomes orient themselves randomly, which is know as the process of independent

*. Low levels of _____ in the female embryo allow the normal development of female sex organs.

Charlene Forest is an associate professor in the Biology department at Brooklyn College, who dedicates her research in to trying to understand the mechanism behind the process of fertilization in algae, as well as what controls expression of gamete-specific genes. To do so, she must understand how sperm and egg gametes first recognize and then fuse with each other. Thus, in order to find what causes the fusion of these gametes, Forest’s lab is cloning genes that prevent the fusion of sperm and egg gametes. She hopes that her research on the fertilization process in algae will help understand the fertilization process in other organisms, particularly humans.

Pink colored spermatozoa (sperm) were surrounded by spermatocytes (formed after meiosis of spermatogonia) and spermotigonia (precursor to sperm)

17) The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

Cell division may happen by either mitosis or meiosis, depending on what type of cell is invovled. Mitosis is a process by which a cell divides to form two daughter cells. They each have the same exact number and kind of chromosomes as the parent cell. Meiosis occurs in the primary sex cells leading to the formation of viable egg and sperm cells. They reduce the number of chromosomes to half in each gamete so that when they are getting furtilized, the species chromosome number is kept even.

CYP19A1 converts AN and TS to E1 and E2b, respectively, in the granulosa cells, which are somatic cells present in the ovaries and the placenta. Furthermore, CYP19A1 can convert TS to E2b in the leydig, seroli, and germ cells found in the testis. This process is crucial for the initiation of spermatogenesis and mitosis of spermatogonia . Both E2b and E1 can be further catalyzed into the third estrogen estriol.

sperm as a superior and the egg as an expelling organ part. Moreover, the features of the egg and

Since the mid 1970’s scientists have understood that one germ cell from each sex are required for the development of a viable embryo. Pathological analyses of human germ cell tumors have provided important biological information regarding the difference of parental genetic origins. Through histopathological analyses of ovarian teratomas and hydatidiform mole functional differences of what the maternal and paternal genome each contribute to cell growth and differentiation was recognition. Ovarian teratomas occur in the ovary and consist of three germimative layers (Linder et al., 1975) whereas hydatidiform mole occurs in the uterus and only contain extra trophoblast (Kajii and Ohama, 1977; Wake et al., 1978) however, both tumors arise from uniparental genomes. Genetic analyses have shown that the cells which result in ovarian teratomas consist only of the maternal genome whereas the hydatidiform mole is only the paternal genome. This work provided the early conceptual framework for the understanding and recognition of the importance and what each of the maternal and parental genomes contributes to the development of a viable

The main focus of this lab was to be able to understand the different phases of mitosis and the cell cycle and also identify what those stages may look like. Mitosis is the process in which concerns the production of new cells. For example, when apoptosis(cell death) the process of Mitosis begins to replace the dead cells. To be able to familiarize ourselves with this concept, we took a sample of an onion root and had it put through a process to be able to look at the different phases under the microscope. We found that the majority of the cells were mostly undergoing Interphase or Prophase which are the phases in charge of crossing over of DNA and where the chromosomes then become visible and the nuclear envelope dissipates. The conclusion of this lab was that Mitosis is essential for the production of new cells. In the case of the onion root sample, the cells were damaged leading to the tester to undergo Mitotic cell division and it was found that mainly Interphase and Prophase were the stages that occurred in this lab.