Question

Which of the following statements accurately describes a difference between mitosis and meiosis? a. Mitosis may produce diploid cells, whereas meiosis produces haploid cells. b. Homologous chromosomes synapse during meiosis but do not synapse during mitosis. c. Crossing over commonly occurs during meiosis, but it does not commonly occur during mitosis. d. All of the above are correct. e. Both a and c are correct.

Short answer

All of the above statements (option D) accurately describes a difference between mitosis and meiosis.

Step-by-step solution

Understanding Mitosis and Meiosis

Mitosis and meiosis are two different types of cell division. Mitosis results in two cells (called daughter cells) that are identical to the parent cell, they are diploid cells which means they have two sets of chromosomes. On the other hand, meiosis produces four cells that are not identical to the parent and they are haploid, containing only one set of chromosomes.

Understanding Synapsing and Crossing Over

Synapsing of homologous chromosomes and crossing over are processes that occur during meiosis. Homologous chromosomes synapse, or pair up, during the first division of meiosis. Crossing over is the exchange of genetic material between these paired chromosomes, leading to a reshuffling of genetic material and therefore increased genetic diversity.

Matching Statements to Concepts

Given the information from steps 1 and 2, it can be determined that: A. Mitosis does indeed produce diploid cells and meiosis produces haploid cells. So, statement A is correct. B. Homologous chromosomes do synapse during meiosis but not during mitosis. Therefore, statement B is also correct. C. Crossing over occurs during meiosis and not commonly during mitosis, so Statement C is also correct.

Key concepts

Mitosis

In the process of mitosis, cells divide to produce two identical daughter cells. These daughter cells are diploid, meaning they contain two complete sets of chromosomes, just like the parent cell. Mitosis is fundamental for growth, development, and tissue repair in multicellular organisms.
Mitosis consists of several stages: prophase, metaphase, anaphase, and telophase. During these stages, chromosomes are duplicated and evenly distributed into the new cells. This ensures that the genetic information remains consistent in each daughter cell.
Key characteristics of mitosis include:

• Produces two identical daughter cells.
• Occurs in somatic (non-reproductive) cells.
• Maintains the chromosome number of the parent cell.
• Essential for asexual reproduction.

Meiosis

Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in four haploid cells. These cells have one set of chromosomes and are genetically diverse. Meiosis is essential for sexual reproduction and the formation of gametes, such as sperm and eggs.
The stages of meiosis include meiosis I and meiosis II, each of which has multiple phases similar to mitosis. However, the key difference is the reduction of chromosome number and genetic variation introduced during this process.
Important attributes of meiosis are:

• Produces four genetically diverse haploid cells.
• Occurs in germ cells (sex cells).
• Involves two rounds of cell division.
• Facilitates genetic diversity and evolution.

Chromosomes

Chromosomes are structures within cells that contain DNA, the molecule that carries genetic instructions. In humans, chromosomes come in pairs; we have 23 pairs. Each parent contributes one chromosome to every pair, resulting in a diploid set in somatic cells and a haploid set in gametes after meiosis.
Chromosomes ensure DNA is accurately copied and distributed during cell division. Different organisms have varying numbers of chromosomes, which is crucial for maintaining species-specific traits.
Key points about chromosomes are:

• Carry hereditary information in the form of genes.
• Compose the genetic architecture of an organism.
• Pair up during cell division for proper genetic distribution.
• Diverse in structure, varying in size and gene content.

Crossing Over

Crossing over is a vital process that occurs during meiosis, specifically in prophase I. It involves the exchange of genetic material between homologous chromosomes. This exchange results in new, recombinant chromosomes, which increases genetic variation among offspring.
Crossing over ensures that siblings have unique genetic makeups, apart from identical twins. It plays a critical role in evolution by promoting genetic diversity within a population.
Essential aspects of crossing over include:

• Occurs during prophase I of meiosis.
• Involves homologous chromosomes swapping segments.
• Increases genetic diversity in sexual reproduction.
• Contributes to the natural variation within a species.