The image provided is a diagram of the stages of
meiosis, which is a type of cell division that reduces the chromosome number by half, resulting in the production of gametes (sperm and egg cells). The process of meiosis consists of two sequential divisions:
Meiosis I and
Meiosis II. Each division has its own set of phases: Prophase, Metaphase, Anaphase, and Telophase.
Task:
The task is to fill in the missing diagrams for each phase of Meiosis I and Meiosis II, based on the given starting point (Prophase I) and the final result (Telophase I and Telophase II).
Solution:
####
Meiosis I Stages:
1.
Prophase I:
- Homologous chromosomes pair up (synapsis), forming tetrads.
- Crossing over may occur between non-sister chromatids.
- The diagram shows this pairing clearly.
2.
Metaphase I:
- Tetrads align at the metaphase plate (equatorial plane).
- Spindle fibers attach to the kinetochores of homologous chromosomes.
- The diagram should show the tetrads aligned at the center of the cell.
3.
Anaphase I:
- Homologous chromosomes separate, but sister chromatids remain attached.
- Each homolog moves to opposite poles of the cell.
- The diagram should show the homologous pairs moving apart.
4.
Telophase I:
- Chromosomes reach opposite poles.
- Nuclear envelopes may reform, and cytokinesis occurs, resulting in two haploid daughter cells.
- The diagram should show two separate nuclei, each with one chromosome from each homologous pair.
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####
Meiosis II Stages:
5.
Prophase II:
- The nuclear envelope breaks down again.
- Spindle fibers form, and chromosomes condense.
- The diagram should show individual chromosomes (not tetrads) inside the newly formed haploid cells.
6.
Metaphase II:
- Sister chromatids align at the metaphase plate.
- Spindle fibers attach to the kinetochores of sister chromatids.
- The diagram should show the sister chromatids aligned at the center of the cell.
7.
Anaphase II:
- Sister chromatids separate and move to opposite poles.
- The diagram should show the sister chromatids moving apart.
8.
Telophase II:
- Chromosomes reach opposite poles.
- Nuclear envelopes reform, and cytokinesis occurs, resulting in four haploid daughter cells.
- The diagram should show four separate nuclei, each with one chromosome.
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Filling in the Diagram:
Based on the above explanations, here is how the diagram should be completed:
####
Top Row (Meiosis I):
-
Prophase I: Already filled in (tetrads forming).
-
Metaphase I: Draw tetrads aligned at the metaphase plate.
-
Anaphase I: Draw homologous chromosomes separating.
-
Telophase I: Draw two separate nuclei, each with one chromosome from each homologous pair.
####
Bottom Row (Meiosis II):
-
Telophase II: Already filled in (four separate nuclei).
-
Anaphase II: Draw sister chromatids separating.
-
Metaphase II: Draw sister chromatids aligned at the metaphase plate.
-
Prophase II: Draw individual chromosomes inside the haploid cells.
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Final Answer:
The completed diagram should look like this (described in words):
1.
Prophase I: Tetrads forming.
2.
Metaphase I: Tetrads aligned at the metaphase plate.
3.
Anaphase I: Homologous chromosomes separating.
4.
Telophase I: Two separate nuclei, each with one chromosome from each homologous pair.
5.
Prophase II: Individual chromosomes inside haploid cells.
6.
Metaphase II: Sister chromatids aligned at the metaphase plate.
7.
Anaphase II: Sister chromatids separating.
8.
Telophase II: Four separate nuclei, each with one chromosome.
$$
\boxed{\text{See the description above for the completed diagram.}}
$$
Parent Tip: Review the logic above to help your child master the concept of stages of meiosis worksheet.
