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Mitosis and meiosis are both cell division processes, but they differ in purpose, number of divisions, and genetic outcomes. Mitosis produces two identical daughter cells for growth and repair, maintaining the same chromosome number. Meiosis, on the other hand, produces four genetically diverse daughter cells with half the chromosome number, essential for sexual reproduction.
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### 1. Definition
- **Mitosis** is the process of cell division through which a single cell divides to produce two genetically identical daughter cells.
- **Meiosis** is the process of cell division that reduces the chromosome number by half, resulting in four genetically distinct daughter cells, typically involved in the production of gametes (e.g., sperm and eggs).
### 2. Purpose and Function
- **Mitosis:**
- Produces cells for growth, repair, and asexual reproduction.
- Maintains the same ploidy (i.e., if the parent cell is diploid \(2n\), the daughter cells are also diploid \(2n\)).
- **Meiosis:**
- Produces gametes for sexual reproduction.
- Reduces the chromosome number from diploid \(2n\) to haploid \(n\) in each gamete, ensuring that when two gametes unite during fertilization, the original diploid number is restored.
### 3. Number of Divisions and Outcome
- **Mitosis:**
- Involves one division cycle.
- Results in two daughter cells that are genetically identical to the parent cell.
- **Meiosis:**
- Consists of two successive division cycles, called Meiosis I and Meiosis II.
- Results in four daughter cells, each genetically distinct from the parent cell and from each other.
### 4. Genetic Variation
- **Mitosis:**
- No crossing over or recombination occurs, so the daughter cells have identical genetic information as the parent cell.
- **Meiosis:**
- Crossing over occurs during prophase I, where homologous chromosomes exchange genetic material. This leads to genetic recombination.
- Independent assortment during metaphase I also contributes to genetic variation among the daughter cells.
### 5. Synapsis of Chromosomes
- **Mitosis:**
- Homologous chromosomes do not pair up.
- **Meiosis:**
- Homologous chromosomes pair up during prophase I (a process known as synapsis) which facilitates crossing over.
### 6. Summary Table
| Feature | Mitosis | Meiosis |
|------------------------------|---------------------------------------------|-------------------------------------------|
| **Purpose** | Growth, repair, asexual reproduction | Production of gametes for sexual reproduction |
| **Number of Divisions** | One | Two |
| **Number of Daughter Cells** | Two | Four |
| **Genetic Identity** | Daughter cells are identical | Daughter cells are genetically different |
| **Ploidy** | Maintains \(2n \to 2n\) | Reduces \(2n \to n\) |
| **Crossing Over** | Does not occur | Occurs during prophase I |
Each process plays a crucial role in the life cycle of an organism, contributing distinctively either to the maintenance of the organism's tissues or to the diversity seen in sexually reproducing populations.
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