Download Mitosis and Meiosis NCSCOS Objective 3.02 Chapter 8.2

Name: _____________________________________
Biology, Spring 2011
Topic 10: Mitosis and Meiosis
NCSCOS Objective 3.02
Chapter 8.2, 10.2
Key Terms:
Asexual reproduction
Sexual reproduction
Genetic variation
Nondisjunction
Mitosis
Cancer
Meiosis
Gamete
Tetrad
Haploid
Diploid
Crossing over
Fertilization
Homologous chromosomes
Independent assortment
Testing Your Knowledge:
1. Compare mitosis and meiosis.
Mitosis
Meiosis
Asexual
Sexual
Occurs in which cells:
Somatic cells (body cells)
Number of divisions:
1
Gametes / sex cells
(sperm, egg)
2
Chromosome number is
maintained
(diploid to diploid)
2
Chromosome number is
halved
(diploid to haploid)
4
Daughter cells
Gametes (sperm, egg)
Identical
NOT identical
Type of reproduction (asexual
or sexual):
How does chromosome
number change?
Number of resulting cells:
Resulting cells called:
New cells are:
(identical or not identical)
Name: _____________________________________
2. Complete the chart to describe mitosis
Name of stage What happens during this stage?
Interphase
Cell grows, respiration, DNA
replication
Prophase
DNA condenses into chromosomes,
nuclear membrane disappears,
centrioles and spindle fibers form
Metaphase
Spindle fibers attach to chromosomes
and chromosomes line up at center of
cell
Sketch of cell in stage
Name: _____________________________________
Name of stage
What happens during this stage?
Anaphase
Chromosomes are pulled to opposite
sides of the cell by the spindle fibers
Telophase
2 nuclear membranes form
Cytokinesis
Cytoplasm divides
Sketch of cell in stage
3. What is cancer?
Cancer happens when cells replicate out of control.
4. Describe the general process of meiosis.
Meiosis is similar to mitosis. In meiosis there are two divisions and the resulting cells
have one-half the number of chromosomes of the original cell. In meiosis crossing over
or nondisjunction may occur resulting in genetic variation.
Name: _____________________________________
5. What is crossing over?
Crossing over is when non-sister chromatids exchange segments of DNA. This allows
for genetic variation.
6. Explain nondisjunction.
Nondisjunction occurs when chromosomes fail to separate properly. Nondisjunction
results in cells having an abnormal number of chromosomes (some cells have too many
chromosomes, some cells are missing chromosomes). Trisomy 21 (Down Syndrome),
Klinefelter’s Syndrome, Triple-X Syndrome and Turner’s Syndrome are examples of
genetic disorders caused by nondisjunction.
7. Explain the law of independent assortment.
The law of independent assortment says that chromosomes will segregate and assort
randomly during meiosis to produce genetically diverse gametes.