bio181L 08 worksheet lab 8 PDF

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Alizah Yrigolla

Cell Division Worksheet Compare the nuclear and chromosomal activities in mitosis and meiosis by completing the following table.

Comparing Nuclear and Chromosomal Activities in Mitosis and Meiosis Table 1 Activities

Mitosis

Synapsis does not occur during Mitosis.

Synapsis occurs in meiosis during prophase 1.

Crossing over does not occur during mitosis.

Crossing over does not occur during mitosis.

Synapsis

Crossing Over

When Centromeres Split

Meiosis

Centromeres are split during anaphase Centromeres only split during anaphase. because that is when the centromeres are being pulled apart. The chromosomes sister chromatids

Anaphase I: The double chromosomes

separate and move to opposite sides.

separate into its own pair of chromosomes

Chromosomes Structure and Movement During Anaphase

Anaphase II: The chromosomes split into one chromatid.

In Mitosis, there is only one division.

In meiosis, there are two divisions.

Two sister cells are created

Four daughter cells are created

Number of Divisions

Number of Cells Resulting

Number of Chromosomes on Daughter Cells Genetic Similarity of Daughter Cells to Parent Cells

Each daughter cell created has the exact same Each daughter cell created has 23 chromosomes number of chromosomes which is 46

In mitosis, the daughter cells are In meiosis, the daughter cells are not genetically identical to the parent as well genetically identical. as each other.

1

Section 1: Observing Phases of Mitosis and Cytokinesis Complete Table 2 using one of the following options: 1. Using a pencil, draw all structures that characterize each phase of cell division, including nucleus, nuclear envelope, nucleolus, aster, centromere, chromatids, chromosomes, spindle fibers, centrioles, and cleavage furrow. All drawings should be clear, colored, and labeled. 2. Take a photo of the field of view in the microscope, and label the nucleus, nuclear envelope, aster, centromere, chromatids, chromosomes, spindle fibers, centrioles, and cleavage furrow. Be sure to crop all of the photos, and paste them to the appropriate cell for each phase. Table 2

White Fish and Onion Root Cells at Various Stages of Mitotic Cells Division Phase of Cell Division

White Fish

Onion Root

Brief Description of Each Phase Chromosomes groups together and crossing over occurs

Prophase

The nuclear envelope breaks down.

Prometapha se

Chromosomes attach to spindle fibers.

Metaphase

Hint: Notice the absence of the cell wall in the white fish slide as most cells appear as round or irregularly shaped. In addition, aster is an array of microtubules at the poles around which the microtubules of the spindle and asters appear to radiate.

White Fish and Onion Root Cells at Various Stages of Mitotic Cells Division continued Phase of Cell Division

White Fish

Onion Root

Brief Description of Each Phase

Chromosomes move away from each other to the opposite sides of the spindle. Anaphase

chromosomes move to opposite ends and two nuclei are formed Telophase

Hint: Notice the absence of the cell wall in the white fish slide as most cells appear as round or irregularly shaped. In addition, aster is an array of microtubules at the poles around which the microtubules of the spindle and asters appear to radiate.

Section 2: Modeling Interphase and Meiosis Draw each step or utilize the photos taken to show a comprehensive figure displaying the steps of meiosis. If drawing, use colors to identify chromosomes and crossing over.

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Cell Division Worksheet

Review Questions 1. Describe any observations made regarding differences and similarities between plant (onion root) and animal (white fish) cells in regard to each of the phases of mitosis.

Some similarities between plant and animal cells in regard to each phase of mitosis are that chromosomes condense during prophase, in prometaphase the nuclear envelope breaks down, in metaphase the chromosomes align at the equator, in anaphase chromosomes move towards opposite poles, and in telophase the nuclear envelope forms again while chromosomes condense, and the spindle breaks down. Some differences are centrosomes are essential in animal cell division, but not present in plant division. In animal cells the cleavage furrow occurs more towards the center, but in plant cells the cell grows outward instead of inward.

2. In the modeling meiosis portion of the lab, describe how the new nuclei formed in meiosis I as being diploid (2n) or haploid (n).

At the end of meiosis there are 2 haploid cells. They are called haploid because they have half the chromosomes of a diploid cell.

3. Explain how crossing over changed the structure of the sister chromatids in the new nuclei in meiosis I.

Crossing over changed the structure of the sister chromatids in the new nuclei in meiosis 1 because a crossover is a cross connection that forms from breakage and rejoining between sister chromatids

4. What are the total number of cells at the end of meiosis II? At the end of Meiosis there are a total of 4 cells.

5. Based on the model in class, how many chromosomes are in each daughter cell at the end of meiotic cell division? Based on the model in class, there are 23 chromosomes in each daughter cell at the end of meiotic cell division.

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Cell Division Worksheet 6. Based on the model in class, how many chromosomes were present per cell when the entire process began?

Based on the model in class, there were 48 chromosomes present per cell when the entire process began. 7. Based on the model in class, how many of the cells formed by the meiotic division are genetically identical?

Based on the model in class, 0 cells formed by meiotic division are genetically identical 8. Explain the results obtained in meiotic cell division in terms of independent assortment and crossing over.

Meiotic cell division results in 4 daughter haploid cells, each with only half the number of chromosomes as a diploid cell. Independent assortment is the random formation of combinations of chromosomes. It this didn’t occur, then the offspring would be identical to the parents. Crossing over is when two chromosomes of a homologous pair exchange equal segments with each other. Crossing over enhances the number of possibilities....