Question

1. Pre Lab Question (Do these BEFORE using the Gizmo.) During mitosis, a single cell divides to produce two daughter cells. What must happen in the original cell so that each of the daughter cells has a complete set of chromosomes?

Answer: The DNA (or chromosomes) must be duplicated before cell division.

2. Pre Lab Question (Do these BEFORE using the Gizmo.) During sexual reproduction, two sex cells fuse to create a fertilized cell with a complete set of chromosomes. What must be true about the number of chromosomes in each sex cell?

Answer: The sex cells will have half the number of chromosomes as the fertilized cell.

3.Activity A: Steps in meiosis. 1. Get the Gizmo ready: Make sure the STEPS tab is selected. 2. Choose the Male cell. 3. Click on the DNA to copy it to proceed to prophase I. Observe: (Prophase I) Click on the nucleus to break it down then click on the DNA to condense it into chromosomes. Drag the centrosomes to the top and bottom of the cell. How many chromosomes does this cell have?

Answer: 4

Observe Prophase 1, Metaphase 1, Anaphase 1, Telophase 1 and cytokinesis.
At the end of the first half of Meiosis and the start of Prophase II (P II) how many chromosomes does each cell have?

Answer: 2

5.Observe: Go through the steps of the second half of meiosis until you reach the end of telophase II, following the instructions at the top right corner. True or False? Before prophase II begins, the DNA in the cell duplicates itself.

Answer: False

6.True or False? During metaphase II, homologous chromosomes pair up as in metaphase I.

Answer: False

7.How does anaphase II differ from anaphase I? True or False? During anaphase I, whole chromosomes are pulled to opposite sides of the cell. During anaphase II, the chromosomes are split and sister chromatids are pulled to opposite sides of the cell.

Answer: True

8.At the end of anaphase II, how many chromatids are on each side of the cell?
Answer: 2

9. After cytokinesis II, how many cells have been formed from the parent cell?
Answer: 4

10. Comparing female and male gametes. Make sure the STEPS tab is selected. Click Reset. Compare: Click on the Female button. For the female cell, proceed through meiosis until you finish telophase II and cytokinesis II. Which statement below matches your observations?

Answer: Same chromosomal division as with male but unlike male the female division
results in one big and three small cells.

Answer 1

During mitosis, DNA must be duplicated; the sex cells have half the number of chromosomes as the fertilized cell; Meiosis involves reduction of chromosome and chromatid numbers.

During mitosis, a single cell divides to produce two daughter cells. In order for each of the daughter cells to have a complete set of chromosomes, the DNA (or chromosomes) must be duplicated before cell division.

In sexual reproduction, two sex cells fuse to create a fertilized cell with a complete set of chromosomes. Each sex cell will have half the number of chromosomes as the fertilized cell.

Meiosis is a series of events that arrange and separate chromosomes and chromatids into daughter cells. The first half of meiosis reduces the number of chromosomes and chromatids, resulting in cells with half the number of chromosomes as the original cell. The second half of meiosis separates the sister chromatids, resulting in cells with a full set of chromosomes but half the number of chromatids as the original cell.