Consider the Concepts
Experiment: 1. A common misconception about meiosis appears when students identify which of the two divisions converts a diploid cell into two haploid cells. Meiosis I is the division immediately following DNA replication and replication does not occur again before meiosis II. However, meiosis I is the "reduction" division when a diploid cell forms two haploid cells. If the DNA duplicated before meiosis I, how do the daughter cells become haploid?
DNA must replicate before mitosis or meiosis can occur. If daughter cells are to receive a full set of genetic information, a duplicate copy of DNA must be available. Before DNA replication occurs, each chromosome consists of a single long strand of DNA called a chromatid. When a diploid cell undergoes meiosis, four unique haploid daughter cells are produced. It is important for gametes to be haploid
Experiment: Following Chromosomal DNA in Meiosis
2. Why was the model of ONE chromosome composed of TWO identical strands of beads at the beginning of the experiment? To represent the dna sequence.
3. Why did you use the same number of beads and position for the centromere for the two long homologous chromosomes? To represent the set of genes for the mother and father.
4. In terms of DNA sequences and genes, what did the two different bead colors represent? Sister chromatids
5. Considering all the stages of meiosis, when does random chromosome alignment take place? During metaphase 1 and 2
6. Briefly describe the two meiotic events that contribute to genetic diversity in a population. Each gamete (sex cell) is unique due to a process during meiosis called cross-over which (simplified) swaps around some genes to create unique chromosome combinations. meiosis helps to create a population that is not only physically and genetically different but also one, which is perfectly fit to survive.
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