Chapter 8 Cell reproduction

 

1.      Introduction - Life cycle of sea urchin

(use this space for drawing)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Development of multicellular organisms from a single cell

•      cell division

–   cell proliferation

 

•      cell differentiation (specialization) and organization (discussed more in Chapter 11)

 

 

2. Sexual vs. asexual reproduction

•      Sexual reproduction

–   offspring inherits genetic materials from two parents (eg. fertilization of a sperm and an egg)

–   offspring resembles parents but not exactly the same

•      Asexual reproduction

–   offspring inherits genetic materials from one parent (eg. prokaryotes and some eukaryotes)

–   offspring is virtually the same as the parent (clones)

 

 

3. Prokaryotes reproduce by binary fission (Fig 8.3A p129)

•      Prokaryotic cells divide asexually

•      These cells possess a single chromosome, containing genes

•      The chromosome is replicated

•      The cell then divides into two cells, a process called binary fission

 

4. Eukaryotic chromosome

•      Chromosomes contain a very long DNA molecule with thousands of genes (Fig 8.4A, p130) They are packaged as chromatin (DNA/protein complex)

 

•      Individual chromosomes are only visible during cell division

 

 

•      Before a cell starts dividing, the chromosomes are duplicated

- This process produces sister chromatids (Fig 8.4B, p130)

 

 

•      When the cell divides, the sister chromatids separate (Fig 8.4C, p130)

- Two daughter cells are produced

- Each has a complete and identical set of chromosomes

 

 

5. Eukaryotic Cell division

•      Mitosis

–   Cell division to produce somatic cells

–   Chromosomes are evenly distributed to the daughter cells

•      Meiosis

–   Cell division to produce gametes (sperm, egg cells)

–   Number of chromosomes are reduced to half

 

 

6. Functions of mitosis

•      When the cell cycle operates normally, mitotic cell division functions in:

–   Growth (Figure 8.11A)

–   Cell replacement (Figure 8.11B)

–   Asexual reproduction (Figure 8.11C)

 

 

7. Uncontrolled cell division results in tumor development (Figure 8.10, p137)

•      Benign tumors

-          do not spread to other sites

-          may need to be removed

•      Malignant tumors

-          can spread to other tissues (Metastasis)

-          need to be removed