Download Unit 9 obj. Mitosis and Meiosis

UNIT 9 OBJECTIVES - MITOSIS AND MEIOSIS
Dates: Dec. 4 – Dec. 12
Chapters: 5
Assignments:
Investigation 22 - Mitosis
Investigation 23 Limits of Cell Growth
Cancer Handouts
Handout - Mitosis and Meiosis worksheets
Investigation 24
Case of the Dividing Cell
Evaluation: Dec. 12th - TEST - DNA-RNA (Unit 8) and Mitosis and Meiosis
Introduction:
DNA has been found to be the genetic code, the blueprint for all cellular activity. As we now
know, it is located on the chromosomes in the nucleus of eukaryotic cells. The chromosome number may
vary from organism to organism but one characteristic of each organism is that each of their body (somatic)
cells always maintains the same number of chromosomes. The Cell Theory states that cells come from
other cells; meaning that cells divide to produce two new cells called daughter cells. These are identical to
the parent cell in respect to the number of chromosomes they have and the blueprint they carry. The ability
of DNA to duplicate itself gives the nucleus the ability to copy itself. This is called mitosis. The division
of the cytoplasm (Cytokinesis) follows this by dividing the cell in half. For some organisms, this may be a
form of reproduction called Asexual; for multicellular organisms, it is a way to increase the number of cells
thus increasing the size of the organism, or helping to repair or replace old or dying cells.
Meiosis is another form of cell division that is a necessary process for those organisms that carry
out sexual reproduction. In sexual reproduction, there is a combination of chromosomes to make the
offspring. Half come from the female and half from the male. The specialized cells that join are called
gametes or sex cells (better known as egg and sperm). To maintain the proper number of chromosomes for
the species, these cells must undergo a different kind of cell division than mitosis. This process is called
meiosis and is a reduction division or a reduction of the chromosome number by one-half to form gametes.
This process does not take place just anywhere in the body, it occurs only in the gonads (ovaries and testes)
that produce the sex cells.
At the conclusion of this unit the student should be able to:
1. explain why cells divide and under what cellular conditions might they be stimulated to divide.
a. What happens to the surface-to-volume ratio of a cell as it grows?
2. explain the purpose of mitosis. Cytokinesis.
3. list and describe the phases of the cell cycle.
4. explain the importance of metaphase.
5. distinguish between cell division in an animal cell and cell division in a plant cell.
6. define Meiosis I and Meiosis II.
7. explain the importance of Meiosis to sexually reproducing organisms.
chromosomal characteristics of that species?
How does it continue the
8. using cell division in your explanation, define cancer. Explain why it is such a dangerous disease.
Vocabulary:
somatic cells
cancer
cytokinesis
mitosis
meiosis
chromosome
chromatid
centromere
chromatid
centromere
centrioles
spindle fibers
tetrad
haploid (monoploid) (1n)
homologous
crossing-over
synapsis
mutation
diploid (2n)
Extra Credit:
1. A cell is 3um long, 3um wide, and 3 um high. Find the ratio of volume to surface area.
2. Using reference sources, investigate the relationship between mitosis and cancer. What phases of mitosis
might you expect to observe most frequently?