Number of cells observed in each stage of the cell cycle

Table 1: Number of cells observed in each stage of the cell cycle(2 pts)
Predicted %
Number of cells in stage
Total number

of cells counted*
Calculated %












NOTE: You do not have to draw the cells in each of the stages.

Questions (6 pts)

What stage of the cell cycle (not just mitosis) were most of the onion root tip cells in? Does this make sense? Why? Cite source(s) used.

What is the function of mitosis in a cell that is about to divide? Cite source(s) used.

How accurate were your time predictions, based on your data, for each stage of the cell cycle?

Lab 12 Experiment 1: Meiosis

Read through the Lab 12 Introduction material and the instructions for the Lab 12 Experiment 1. Pay attention to the added information under the Week 4 Experiment link regarding these experiments! In the table below, describe the major events that take place in each stage of Meiosis and indicate the number of chromosomes in each. Cite your sources!(14pts)

Major Events
# of Chromosomes in each cell
Meiosis I

Prophase I
Nuclear membrane breaks down and chromosomes condense. Two sets of homologous chromosomes are attached at the centromere. Crossing over will occur between the homologous pairs.
Metaphase I

Anaphase I

Telophase I

Meiosis II

Prophase II

Metaphase II

Anaphase II

Telophase II

Sources used:

Questions(12 pts)

Name at least two differences between Meiosis I and Meiosis II in terms of what is produced and what occurs with the chromosomes. Cite source(s) used.

Name and briefly describe two processes that occur during meiosis that contribute to genetic variation. Cite source(s) used.

At the beginning of meiosis I are the cells diploid or haploid?

What are they at the beginning of meiosis II?

Why is it necessary to reduce the chromosome number of gametes (egg and sperm), but not other cells of an organism? Cite source(s) used.

If humans have 46 chromosomes in each of their body cells, determine how many chromosomes you would expect to find in the following cells:

Sperm _______________
Egg _________________
Daughter cell from mitosis __________
Daughter cell from Meiosis II __________

Investigate one of the diseasesfrom the following list.Include the following:
Name of the disease or disorder
What is the type of mutation and when might it occur?
What chromosome is affected?
What are the consequences?
What is the incidence rate of this disease or disorder?

Down Syndrome Turner Syndrome Klinefelter Syndrome
Jacobs Syndrome Triple X Edward Syndrome
Patau Syndrome Hemophilia Cri-du-chat Syndrome
Cystic fibrosis Prader-Willis Syndrome Fragile X

Remember to properly cite your sources! (Minimum of 250 words) (6 pt)

Posted in Frequent Questions.