Meiosis and Mitosis

Introduction

• The video presents a comparison between mitosis and meiosis.
• The processes are shown side-by-side to understand their similarities and differences.

What is Mitosis and Meiosis

• Two important processes for creating new cells.
• Mitosis results in body cells.
• Meiosis results in the formation of sperm and egg cells (gametes).

Primary Cells

• The primary cell in both cases is diploid (2N).
• Contains two sets of chromosomes.
• Humans have 46 chromosomes (23 from the mother and 23 from the father).
• During interphase, the cell duplicates the chromosomes.

PMAT Stages

• Both mitosis and meiosis go through the PMAT stages (Prophase, Metaphase, Anaphase, Telophase).
• Meiosis goes through these stages twice.

Interphase

• Not a part of mitosis or meiosis.
• Duplicates the chromosomes before starting mitosis/meiosis.

Prophase

• Mitosis: Chromosomes become visible and thicken.
• Meiosis: Chromosomes pair with their homologous pairs and crossing over occurs (exchange of genetic information).

Metaphase

• Mitosis: Chromosomes line up in the middle of the cell in a single line.
• Meiosis: Chromosomes line up in the middle of the cell but stay in pairs.

Anaphase

• Mitosis: Chromatids are pulled apart to either side of the cell.
• Meiosis: Chromosomes (whole) are pulled apart, not chromatids.

Telophase

• Mitosis and Meiosis I: Chromosomes are at opposite ends and a new nucleus forms.
• Cytokinesis begins to complete the actual cell division.
• Result of Mitosis: Two identical cells (46 chromosomes each).

Meiosis II

• A second phase of meiosis.
• The stages are repeated but without homologous pairs and crossing over.

Prophase II

• Chromosomes thicken in both cells.

Metaphase II

• Chromosomes line up in a single line.

Anaphase II

• Chromatids are pulled apart.

Telophase II

• Chromosomes are at opposite ends and a new nucleus forms.

Cytokinesis - Meiosis II

• Cytoplasm division follows, resulting in four non-identical cells (23 chromosomes each).
• Males produce sperm cells, females produce egg cells.
• When sperm and egg unite, a zygote is formed, starting a series of divisions using mitosis.

Conclusion

• The video illustrates the differences and similarities between mitosis and meiosis.
• Reminder to stay curious about knowledge and continue studying further.