Biology Lesson 2.2: Mitosis

Mitosis Overview

• Main purpose of mitosis is to enable cell division for growth, repair, and asexual reproduction.
• During mitosis, the nuclear envelope disintegrates to allow separation of chromosomes.
• Kinetochore is a protein structure on chromosomes that facilitates attachment to spindle fibers for chromosome movement during cell division.
• The final stage of mitosis in animal cells is cytokinesis, where the cell divides its cytoplasm, resulting in two separate daughter cells.
• Key difference between mitosis in animal and plant cells is that plant cells form a cell plate during cytokinesis, while animal cells undergo cleavage furrow formation.

Mitotic Spindle and Chromosome Dynamics

• When the mitotic spindle breaks down, it results in the loss of the structure that organizes and segregates chromosomes, potentially leading to errors in chromosome distribution.

Meiosis Overview

• One parent cell produces four daughter cells during meiosis, through two rounds of division.
• Daughter cells contain half the number of chromosomes compared to the parent cell, resulting in haploid cells from a diploid parent.
• DNA replicates once during meiosis, prior to the first division.
• Synapsis occurs during prophase I of meiosis, allowing homologous chromosomes to pair closely and exchange genetic material.

Genetic Variation in Meiosis

• Crossing-over during meiosis leads to genetic recombination, enhancing genetic diversity among daughter cells.
• During Anaphase I of meiosis, homologous chromosomes are pulled apart to opposite poles of the cell.
• The final stage of Meiosis I is telophase I, where the cell divides into two haploid cells.

Test your knowledge of mitosis, the process of nuclear division that results in two identical daughter cells. Learn about the different stages of mitosis, including prophase, metaphase, anaphase, and telophase.