Question

LAB 12: Following Chromosomal DNA Movement Through Meiosis

I need help with diagramming Meiotic Division WITH AND WITHOUT crossing over using beads (for each phase).

Answer 1

Okay, the purpose for this activity is to watch the differences in the results. Here are the diagrams:

Prophase 1. The homologous chromosomes cross over. Creating combinations not found in the parental chromosomes Metaphase 1. Homologous chromosomes align paired at the center and attach their centromeres to the cytoskeleton Anaphase 1. Homologous chromosomes get segragated Telophase 1. Two cells result, each of them has half the genetic charge but they keep their sister chormatides Telophase 2. Four cells result, they have only one copy of all the human genes. They have gene combinations not found in the parenta) shromosomes Anaphase 2. Sister chromatides get segragated Metaphase 2. Sister chromatides align at the center and attach their centromeres to the cytoskeleton Prophase 2 Cells prepare for division. There is no cross over event here

here we can see a meiosis event with recombination, the special traits are found in the first circle where crossing over occurs, and in the last circle where we can see the result of crossing over.

Now, without crossing over:

Prophase 1. Cells prepare for division, they condense to be able to get segrated. Metaphase 1. Homologous chromosomes align paired at the center and attach their centromeres to the cytoskeleton Anaphase 1. Homologous chromosomes get segragated Telophase 1. Two cells result, each of them has half the genetic charge but they keep their sister chormatides Félophase 2. Four cells result, they have only one copy of each human gene, and each chromosome here is identical to a parental chromosome Anaphase 2. Sister chromatides get segragated Metaphase 2. Sister chromatides align at the center and attach their centromeres to the cytoskeleton Prophase 2 Cells prepare for division. There is no cross over event here

No crossing over event occurs in the first circle, then we proceed to equally segregate homologous chromosomes and then sister chromatides. The result is four cells, they have the same genetic charge as the one produced with crossing over, but this time the cells are genotipically identical to the parental chromosomes.