Lake Tahoe Community College
Fall Qtr
Bio 101
Instructor: Sue Kloss
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Chapter 8 - Cell Division
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I. Connections between cell division and reproduction
A. Like begets like , more or less
1. only people beget people, only starfish beget starfish
2. asexual reproduction
3. chromosomes contain most of the organisms DNA
4. in sexually reproducing species, offspring generally resemble parents, not identical to parents
B. cells arise only from preexisting cells
1. the perpetuation of life is based on cell division
2. cell division perpetuates life in 2 ways
C. Prokaryotic cell division
1. prokaryotes
2. in prokaryotes, most genes are on single, circular chromosome w/ assoc. proteins
II. Eukaryotic Cell Cycle and Mitosis
A. large complex chromosomes of eukaryotes duplicate with each cell division
1. eukaryotic cells
2. genes are grouped into nucleus
3. chromosomes are chromatin
4. one long DNA molecule
5. well before division, a cell duplicates its chromosomes
B. Cell cycle multiplies cells
1. cell division
2. keeps total number in your body constant
3. cell cycle - orderly sequence of events
a. interphase
b. DNA duplication occurs in (approx) the middle of interphase
4. cell division consists of 2 processes - mitotic phase (M)
a. mitosis
b. cytokinesis
5. mitosis is unique to eukaryotes
C. Cell division is continuum of dynamic changes
1. Interphase
2. prophase 3. metaphase
4. anaphase
5. telophase and cytokinesis
D. Cytokinesis differs for plant and animal cells
1. animals - cleavage furrow
2. plants - formation of cell plate
E. anchorage, cell density and chemical growth factors affect cell division
1. timing of cell division must be controlled
2. anchorage
3. cells won’t divide
F. growth factors signal cell cycle control system
1. 3 key checkpoints
G. Cancers - uncontrolled growth
1. benign tumors
2. malignant tumors
3. types of cancers
4. ignore growth factor or manufacture it themselves
5. ignore density dependence
IV. Meiosis and crossing over
A. somatic cells (Body cells) have 46 chromosomes
1. homologous chromosomes
B. gametes have a single set of chromosomes
1. diploid (2n)
2. cell with single chromosome set is haploid
5. sex - haploid sperm joins w/ haploid egg - diploid zygote
C. Meiosis reduces diploid chromosome state to haploid
1. interphase
2. Prophase I
3. metaphase I
4. anaphase I
5. telophase I
6. Meiosis II.
Lesson Objectives/Homework Chapter 8
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Compare the relationship between parents and offspring in asexual vs. sexual reproduction
Why is the theory that cells can only come from other cells so important?
Explain how daughter prokaryotic chromosomes are separated from each other in binary fission.
Compare the structure of prokaryotic and eukaryotic chromosomes.
List the phases of mitosis and describe the events of each phase. Describe the functions of mitosis.
Compare cytokinesis in plants and animals.
What are homologous chromosomes?
Distinguish between:
a. somatic cells and gametes
b. diploid and haploid cells
c. autosomes and sex chromosomes
9. List the phases of meiosis I and meiosis II and describe the characteristic events of each.
10. Describe key differences between meiosis and mitosis.
11. Explain how independent orientation, crossing over and random fertilization contribute to genetic variation in sexually
reproducing organisms.