Gametogenesis: Spermatogenesis and Oogenesis Explained

Posted on Nov 8, 2024 in Biology

Gametogenesis

Spermatogenesis vs. Oogenesis

Multiplication

Oogenesis: Occurs only during the embryonic stage. Primordial germ cells (PGCs) give rise to oogonia (2n, 2c).

Spermatogenesis: Starts during the embryonic stage and pauses until puberty. PGCs give rise to spermatogonia (2n, 2c).

Growth

Oogenesis: Occurs during the embryonic stage, where oocytes develop into primary oocytes (2n, 4c).

Spermatogenesis: Continues at puberty. Spermatogonia develop into primary spermatocytes (2n, 4c).

Maturation

Oogenesis:

  • The first part takes place during the embryonic stage, resulting in primary oocytes that remain latent in Prophase I.
  • The second stage occurs from puberty until around age 55. During each ovarian cycle, meiosis resumes, producing a secondary oocyte (n, 2c) from each primary oocyte. The secondary oocyte arrests at metaphase II and a polar body is formed. The second meiotic division only completes if fertilization occurs, resulting in an ovum (n, c).

Spermatogenesis:

  • Begins at puberty and continues until the end of life, lasting approximately 8 weeks.
  • The first meiotic division produces two secondary spermatocytes (n, 2c).
  • The second meiotic division results in four spermatids (n, c).
  • Each spermatid undergoes spermiogenesis, transforming into a spermatozoon (n, c).

Mitosis and Meiosis Review

Multiple Choice Questions

  1. In what stage of mitosis are chromosomes arranged in the cell’s equatorial plane?
    1. Anaphase
    2. Interphase
    3. Prophase
    4. Metaphase
    5. Telophase
  2. A diploid cell contains in its nucleus:
    1. An even number of chromosomes
    2. An odd number of chromosomes
    3. A copy of each homologue
    4. An even or odd number of chromosomes
    5. Two sister chromatids of each chromosome during the G1 stage
  3. The synthesis of new DNA occurs during:
    1. Prophase
    2. Interphase
    3. Mitosis
    4. Cytokinesis
    5. Anaphase
  4. When do homologous chromosomes pair?
    1. Only in mitosis
    2. Only in meiosis I
    3. Only in meiosis II
    4. Only in cytokinesis
    5. Neither in mitosis nor meiosis
  5. If a corn plant has a diploid number of 68 chromosomes, how many chromosomes are in its pollen?
    1. 23 chromosomes
    2. 68 chromosomes
    3. 34 chromosomes
    4. 136 chromosomes
    5. None of the above
  6. The chromosomes in a human stomach cell have:
    1. 46 pairs of chromosomes
    2. 23 pairs of chromosomes
    3. 23 chromosomes
    4. 24 pairs of chromosomes
    5. 48 chromosomes
  7. During cell division, the mitotic spindle becomes visible for the first time in:
    1. Telophase
    2. Metaphase
    3. Anaphase
    4. Late prophase
    5. Interphase
  8. Meiosis is an important cellular process because:
    1. It helps reduce chromosomal material by half
    2. It has similar stages to mitosis
    3. It helps produce sexual gametes
    4. It facilitates genetic variability
    5. All of the above
  9. A three-month-old embryo has:
    1. A haploid chromosome number
    2. A diploid chromosome number
    3. A triploid chromosome number
    4. All of the above
    5. None of the above
  10. A sex chromosome:
    1. Has DNA
    2. Has nitrogenous bases
    3. Has a phosphate group
    4. Has a pentose sugar

    Choose the correct combination:

    1. I only
    2. I and II only
    3. II and III only
    4. II, III and IV only
    5. I, II, III and IV
  11. Meiosis is characterized by:
    1. Reducing DNA
    2. Having two divisions
    3. Producing genetic variability
    4. Generating different cells
    5. All of the above
  12. The process where DNA polymerase copies a DNA strand occurs in:
    1. Mitosis
    2. Metastasis
    3. Synthesis (S phase)
    4. Mutation
    5. Chromosomal permutation
  13. Carcinogenic agents include:
    1. Ultraviolet radiation
    2. Some types of viruses, such as herpes
    3. Some components of cigarettes
    4. Genetic factors

    Choose the correct combination:

    1. I only
    2. I and II only
    3. I, II and III only
    4. II, III and IV only
    5. All of the above
  14. Chromosomal disorders associated with problems in the sex chromosomes include:
    1. Down Syndrome
    2. Turner Syndrome
    3. Klinefelter Syndrome
    4. Patau Syndrome

    Choose the correct combination:

    1. I and II only
    2. II and III only
    3. III and IV only
    4. I and IV only
    5. All of the above
  15. The chromosomal disorder with a karyotype of 44 + X0 corresponds to:
    1. Down Syndrome
    2. Turner Syndrome
    3. Klinefelter Syndrome
    4. Patau Syndrome
    5. Cri-du-chat Syndrome
  16. Eukaryotic chromosomes are duplicated during:
    1. Metaphase
    2. Telophase
    3. Interphase
    4. Prophase
    5. Anaphase
  17. Indicate the correct order of Mitosis:
    1. Interphase, prophase, telophase, anaphase
    2. Metaphase, Anaphase, Prophase, Telophase
    3. Prophase, Metaphase, Anaphase, Telophase
    4. Anaphase, Metaphase, Interphase, Prophase
    5. anaphase, metaphase, prophase, telophase
  18. Cytokinesis corresponds to:
    1. A type of cancer
    2. Cell death
    3. Cytoplasmic division
    4. The movement of the centrioles
    5. The duplication of chromosomes
  19. The cell cycle is not:
    1. An iterative process
    2. A form of reproduction
    3. A process that has four stages
    4. A cycle consisting of interphase and cytokinesis
    5. A process that allows the formation of identical cells
  20. In mitosis, it is not possible to state that:
    1. It ensures the existence of tissue
    2. It ensures the transmission of genetic information
    3. It produces new genetic information
    4. It produces two genetically identical cells
    5. It allows the equitable sharing of genetic material
  21. All body cells have a maximum lifespan and are then removed. This is known as:
    1. Viral infection
    2. Mitosis
    3. Meiosis
    4. Apoptosis
    5. Metastasis
  22. Cancer cells are characterized by:
    1. The induction of apoptosis
    2. High capacity to differentiate
    3. Increased replicative control
    4. Rapid and uncontrolled reproduction
    5. Increased generation of proto-oncogenes
  23. In what stage of the cell cycle do DNA repair processes occur, and chromatin begins to condense?
    1. G0
    2. G1
    3. G2
    4. S
    5. Mitosis
  24. If a cell has a total of 12 chromosomes, how many pairs of chromosomes will a cell have at the end of telophase II of meiosis?
    1. 3
    2. 6
    3. 12
    4. 24
    5. None of the above
  25. If a plant species cell has 24 chromosomes, what will be the result of mitosis?
    1. One cell with 24 chromosomes
    2. One cell with 12 chromosomes
    3. Two cells with 24 chromosomes
    4. Two cells with 12 chromosomes
    5. Four cells with 12 chromosomes
  26. What procedure was used to clone Dolly the sheep?
    1. Vegetative propagation
    2. DNA sequencing
    3. Restriction enzyme cloning
    4. Nuclear transfer
    5. Gene transfer by Agrobacterium tumefaciens
  27. Which of the following is not related to the process of meiosis?
    1. Increased genetic variability
    2. Reduction in the number of chromosomes
    3. Formation of gametes
    4. Obtaining different stem cells
    5. Tissue renewal and repair
  28. Which of the following situations occurs during mitotic telophase?
    1. The nucleoli disappear
    2. Chromatid separation occurs
    3. Genetic material is duplicated
    4. The spindle disappears
    5. Chromosomes are at their most condensed
  29. Which of the following stages of meiosis promotes genetic variability?
    1. Prophase I
    2. Prophase II
    3. Metaphase I
    4. Metaphase II
    5. Anaphase I

    Choose the correct combination:

    1. I only
    2. I and III only
    3. I, II and III only
    4. II, III and IV only
    5. I, III and V only
  30. During interphase of the cell cycle, cells synthesize:
    1. ATP
    2. Lipids
    3. Nucleotide sequences

    Choose the correct combination:

    1. I only
    2. III only
    3. I and II only
    4. II and III only
    5. All of the above
  31. A human meiotic product cell has the same number of DNA molecules and chromosomes as a cell in:
    1. Mitotic Anaphase
    2. Meiotic Prophase I
    3. Meiotic Metaphase II
    4. Meiotic Anaphase I
    5. Meiotic Telophase
  32. A cell with 2n = 12, in Prophase II of meiosis, will have:
    1. 12 single chromosomes
    2. 12 double chromosomes
    3. 6 bivalents or tetrads
    4. 6 double chromosomes
    5. 12 double chromatids
  33. The term “diploid cell” means that a cell:
    1. Presents double-stranded DNA molecules
    2. Has two sets of homologous chromosomes
    3. Can divide its nucleus by mitosis

    Choose the correct combination:

    1. I only
    2. II only
    3. III only
    4. II and III only
    5. I, II and III
  34. Regarding meiosis, it is incorrect to say that:
    1. Tetrads form in Prophase I
    2. Single chromosomes are generated in Meiosis II
    3. Haploid cells are obtained in Meiosis I and II
    4. It can be performed by diploid and haploid cells
    5. The first meiotic division is reductional
  35. Each bivalent observed during meiosis consists of:
    1. Four sets of paired chromosomes
    2. Two chromatids attached to a centromere
    3. Two paired homologous chromosomes
    4. Two paired non-homologous chromosomes
    5. Any two paired chromosomes
  36. Of the following terms, the one that encompasses the other four is:
    1. Meiosis
    2. Mitosis
    3. Growth
    4. Gametogenesis
    5. Spermiogenesis
  37. The cell that has the largest amount of DNA molecules is the:
    1. Spermatid
    2. Polar body I
    3. Primary oocyte
    4. Secondary spermatocyte
    5. Oogonium
  38. If sections are made in the testes of a rat at puberty, the following may be seen under the microscope:
    1. Spermatozoa
    2. Spermatids
    3. Primary spermatocytes

    Choose the correct combination:

    1. I only
    2. II only
    3. III only
    4. I and II only
    5. I, II and III
  39. At the end of the first meiotic division during the maturation stage of oogenesis, each cell:
    1. Has a different amount of cytoplasm
    2. Has one chromosome of each pair of homologues
    3. Has the same number of DNA molecules

    Choose the correct combination:

    1. I only
    2. I and II only
    3. I and III only
    4. II and III only
    5. I, II and III