Cell Division
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Which of the following choices correctly lists the order of development of the listed cell types of oogenesis in humans?
Primary oocyte
Secondary oocyte
Oogonium
Ovum
Oogonium, primary oocyte, secondary oocyte, and ovum
Primary oocyte, secondary oocyte, oogonium, and ovum
Oogonium, secondary oocyte, primary oocyte, and ovum
Ovum, primary oocyte, secondary oocyte, and oogonium
Secondary oocyte, primary oocyte, oogonium, and ovum
Explanation
Oogonia are the primordial oocytes formed inside females either during or shortly after birth. At this time, the formation of primary oocytes occurs during dictyate, which lasts until the surge of luteinizing hormone (LH) just before the onset of puberty. After menarche, a few of these cells will further develop each period into secondary oocytes, which are halted in metaphase II until fertilization. At the end of meiosis II, both polar bodies created to discard extra haploid sets of chromosomes disintegrate, leaving behind the oocyte which can then mature into an ovum. Thus, the correct order is the following order: oogonium, primary oocyte, secondary oocyte, and ovum.
Which of the following best defines oogenesis?
The formation of egg cells through meiosis
The inability to form egg cells during meiosis
The inability to form egg cells during mitosis
The formation of egg cells during prophase
The formation of egg cells during anaphase
Explanation
Gametes are formed during the process of meiosis. Oogenesis is the process by which the female games are produced, which occurs in the ovary. The product of oogenesis is one mature egg from one primary oocyte; this occurs about once every four weeks in humans.
Which of the following best defines oogenesis?
The formation of egg cells through meiosis
The inability to form egg cells during meiosis
The inability to form egg cells during mitosis
The formation of egg cells during prophase
The formation of egg cells during anaphase
Explanation
Gametes are formed during the process of meiosis. Oogenesis is the process by which the female games are produced, which occurs in the ovary. The product of oogenesis is one mature egg from one primary oocyte; this occurs about once every four weeks in humans.
Which of the following best defines oogenesis?
The formation of egg cells through meiosis
The inability to form egg cells during meiosis
The inability to form egg cells during mitosis
The formation of egg cells during prophase
The formation of egg cells during anaphase
Explanation
Gametes are formed during the process of meiosis. Oogenesis is the process by which the female games are produced, which occurs in the ovary. The product of oogenesis is one mature egg from one primary oocyte; this occurs about once every four weeks in humans.
Which of the following choices correctly lists the order of development of the listed cell types of oogenesis in humans?
Primary oocyte
Secondary oocyte
Oogonium
Ovum
Oogonium, primary oocyte, secondary oocyte, and ovum
Primary oocyte, secondary oocyte, oogonium, and ovum
Oogonium, secondary oocyte, primary oocyte, and ovum
Ovum, primary oocyte, secondary oocyte, and oogonium
Secondary oocyte, primary oocyte, oogonium, and ovum
Explanation
Oogonia are the primordial oocytes formed inside females either during or shortly after birth. At this time, the formation of primary oocytes occurs during dictyate, which lasts until the surge of luteinizing hormone (LH) just before the onset of puberty. After menarche, a few of these cells will further develop each period into secondary oocytes, which are halted in metaphase II until fertilization. At the end of meiosis II, both polar bodies created to discard extra haploid sets of chromosomes disintegrate, leaving behind the oocyte which can then mature into an ovum. Thus, the correct order is the following order: oogonium, primary oocyte, secondary oocyte, and ovum.
Which of the following choices correctly lists the order of development of the listed cell types of oogenesis in humans?
Primary oocyte
Secondary oocyte
Oogonium
Ovum
Oogonium, primary oocyte, secondary oocyte, and ovum
Primary oocyte, secondary oocyte, oogonium, and ovum
Oogonium, secondary oocyte, primary oocyte, and ovum
Ovum, primary oocyte, secondary oocyte, and oogonium
Secondary oocyte, primary oocyte, oogonium, and ovum
Explanation
Oogonia are the primordial oocytes formed inside females either during or shortly after birth. At this time, the formation of primary oocytes occurs during dictyate, which lasts until the surge of luteinizing hormone (LH) just before the onset of puberty. After menarche, a few of these cells will further develop each period into secondary oocytes, which are halted in metaphase II until fertilization. At the end of meiosis II, both polar bodies created to discard extra haploid sets of chromosomes disintegrate, leaving behind the oocyte which can then mature into an ovum. Thus, the correct order is the following order: oogonium, primary oocyte, secondary oocyte, and ovum.
A cell is arrested during mitosis. At this stage, distinct chromatids are visible at opposite poles of the cell. Which stage of mitosis does this describe?
Anaphase
Metaphase
Prophase
Telophase
Explanation
The phases of mitosis can be described as follows:
During prophase chromatin condenses to form discrete chromosomes.
During metaphase microtubules attach to the kinetochores and chromatids begin segregating.
During anaphase sister chromatids have been separated and reside at opposite poles of the cell.
During telophase both sets of chromatids are surround by new nuclear membranes and chromosomes decondense into chromatin.
Cytokinesis (the dividing of the cytoplasm into two cells) follows telophase.
If the cell were arrested during telophase, distinct chromatids would no longer be visible.
What is the evolutionary purpose of cells that undergo crossing over?
To increase genetic diversity
To keep mutations from forming
To keep the redundancy of the cell high
To produce two cells instead of one
To produce gametes that are genetically identical
Explanation
Crossing over is a process that happens between homologous chromosomes in order to increase genetic diversity. During crossing over, part of one chromosome is exchanged with another. The result is a hybrid chromosome with a unique pattern of genetic material. Gametes gain the ability to be genetically different from their neighboring gametes after crossing over occurs. This allows for genetic diversity, which will help cells participate in survival of the fittest and evolution.
Many secondary processes enable the primary processes of human gametogenesis to occur smoothly. One important secondary process during human oogenesis is ovarian follicle atresia.
Which of the following is closest to the definition of "ovarian follicle atresia"?
The process by which all but one primary ovarian follicle degenerates and are absorbed back into the ovary, allowing the surviving follicle body to develop into a corpus luteum following ovulation.
The process by which FSH triggers the development of primary follicles into secondary follicles which are ready for ovulation.
The process by which estradiol and luteinizing hormone interact in a positive feedback loop, severely heightening the level of LH and developing the secondary follicle into a tertiary follicle.
The process by which a follicle develops into a corpus luteum following ovulation, which will later release the hormone progesterone into the body.
The process by which the dominant follicle releases large amounts of estradiol during the late follicular phase, preparing the follicle for the LH surge.
Explanation
Follicular atresia is a hormone-controlled, apoptotic (cell-suicide) process by which immature follicles degenerate and are resorbed into the main body of the ovary, leaving one out of typically 20 primary follicles standing as a secondary follicle. This process, moderated by follicle stimulating hormone and tumor necrosis factor alpha (TNF), assists the body in forming the corpus luteum out of the remaining follicle following ovulation, as the body would otherwise not be able to generate enough progesterone to continue the process.
Where does fertilization of the ovum typically occur?
Fallopian tube
Ovary
Uterus
Cervix
Follicle
Explanation
Fertilization typically occurs in the fallopian tube. After fertilization, the diploid zygote will begin the process of implantation into the uterus, where it undergoes mitotic divisions. The resulting multicellular organism is called the embryo, which further develops in the uterus into a fetus.