Cell Biology: Meiosis and Cell Division

Cell Cycle and Cell Division

• Meiosis is significant because it increases genetic variability, helps in the conservation of specific chromosome number, and is important for evolution.
• Most cell organelles duplicate during the S-phase.
• Meiosis is the reduction division.
• The main difference between dividing an animal and plant cell lies in cell plate formation.
• Nerve cells do not divide once they are differentiated.
• Mitosis occurs in diploid cells.
• Interphase is also called the resting stage because no visible changes occur in the nucleus.
• Diploid somatic cells are divided by mitosis.

Meiosis

• Meiosis reduces the number of chromosomes in daughter cells.
• Meiosis produces four genetically dissimilar cells due to crossing over or gene exchange.
• Crossing over is initiated at the pachytene stage.
• Anaphase I is characterized by the separation of homologous chromosomes.
• Interkinesis is a short-lived phase between meiotic divisions I and II.
• Condensation of chromosomes is completed in the prophase stage and can be easily visualized under a microscope.

Mitosis

• Mitosis is called equational division because it is the division of a parent cell into two identical daughter cells having the same amount of DNA as the parent cell.
• Mitosis is essential for the growth of multicellular organisms.
• Kinetochore is essential for cell division, serving as the site of attachment of spindle fibers to the chromosome.
• Spindle fibers attach to the kinetochore of the chromosome.

Cell Cycle

• The interphase is considered the most active stage of the cell cycle, being a period of intense synthesis and growth.
• Disappearance of the nuclear membrane is generally essential for karyokinesis.
• The stage between two meiotic divisions (I and II) is referred to as interkinesis.
• In oocytes, diplotene can last for months or years, during which chromosomes decondense and engage in RNA synthesis.

Cell Division

• Cell division takes place when the cell attains optimum growth.
• Cell division occurs in haploid cells.
• Cell division is characterized by the separation of chromatids.
• Centromere splitting occurs in anaphase stage.
• In some social insects, haploid cells divide by mitosis.

Test your knowledge of meiosis, cell division, and the significance of these processes in biology. Questions cover the stages of meiosis, the role of centromeres, and the importance of these processes in genetics and evolution.