Download Cell Cycle, Mitosis and Meiosis

The Cell Cycle, Mitosis and Meiosis
Biology 110
Fall 2007
Study Guides for Mitosis and Meiosis are available in Angel. The Biology Project Tutorials are also helpful - links in Angel.
Relative time spent in the phases and subphases of the Cell Cycle in plant and animal cells
Scan 100 cells of onion (Allium cepa) root tips and 100 cells of whitefish (Leucichthys sp.) blastula. For each
cell determine what phase/subphase of the cell cycle the cell is in. Keep a tally of your own counts in Table I
below. Record the class compiled data in Table II below. (Note: you can also practice classifying cells in
phases of the cell cycle in the Biology Project Tutorials).
Table I Numbers of Cells in Different Phases/Subphases of the Cell
Cycle in Two Organisms
Individual Data
Onion
Tally
Whitefish
Percent
Tally
Percent
Cells in interphase
Cells in prophase
Cells in metaphase
Cells in anaphase
Cells in telophase
Table I I Numbers of Cells in Different Phases/Subphases of the Cell
Cycle in Two Organisms
Class Data
Onion
Total
Number
Cells in interphase
Cells in prophase
Cells in metaphase
Cells in anaphase
Cells in telophase
Percent
Whitefish
Total
Number
Percent
Your textbook states that interphase typically accounts for 90% of the cell cycle. Does your individual
data agree with this? Does class data agree with this? Suggest a reason that our collected data might not
agree with the typical percentages.
Simulation of mitosis in a cell where 2N=4
Use beads to construct a single cell's (non-replicated) chromosomes for an organism where 2N=4. Use
different colors and lengths to clearly indicate which chromosomes are homologous.
How many homologous pairs are present?
How many chromosomes are present?
Simulate chromosome replication using more beads as needed.
During what phase of the cell cycle does chromosome replication occur? Be specific.
How many chromosomes are now present in your cell?
How many chromatids are now present in your cell?
Move the chromosomes through prometaphase, metaphase, anaphase and telophase.
How do you recognize metaphase?
What event marks the beginning of anaphase?
How do you recognize telophase?
What 2 major actions during anaphase and telophase are controlled by the microtubules of the mitotic spindle
apparatus?
Simulation of meiosis in a cell where 2N=4
Use beads to construct chromosomes as they would appear in a cell at the start of Prophase I of meiosis.
(Think - replicated or not?) Simulate homologous chromosomes coming together in synapsis to form
tetrads. Do not simulate the process of crossing over.
Does synapsis occur during mitosis?
How many chromosomes are present in a tetrad?
How many chromatids?
How many tetrads are present in your cell?
Move the chromosomes into metaphase I position.
How many different ways can a single tetrad line up at metaphase I? (See Fig. 13.10)
Move the chromosomes through anaphase I and telophase I to show chromosomes at the end of meiosis
I.
What event marks the beginning of anaphase I?
Are the daughter nuclei at the end of meiosis I haploid or diploid? How many chromosomes are present in
each nucleus?
Regardless of whether an interphase occurs between meiosis I and meiosis II, is there any replication of genetic
material before prophase II?
Move the chromosomes of each nucleus through metaphase II, anaphase II and telophase II.
What event marks the beginning of anaphase II?
How many cells result from this meiotic division?
Are these daughter cells haploid or diploid?
How many chromosomes does each daughter cell have?
Repeat the simulation of meiosis beginning at Prophase I. Show each synapsed pair of homologous
chromosomes forming a single chiasma and exchanging non-sister chromatid segments during prophase
I. This process is called crossing over.
Are sister chromatids genetically identical if crossing over DOES NOT occur?
Are sister chromatids genetically identical if crossing over DOES occur?
Are non-sister chromatids genetically identical?
How many cells result from this meiotic division?
Are these daughter cells haploid or diploid?
How many chromosomes are present in each daughter cell?
How many of the daughter cells contain chromosomes which represent new genetic combinations
(chromosomes different from any of the parental chromosomes)? (Note: You must consider all possible results
of this meiotic division)