Chapters 18, 19, 20, 21
Cell Division- Mitosis (pages 379-391)
Early Fetal Development (page 436, powerpoint slides 44-48)
Role of Genes/Chromosomes in Inheritance (pages 392-397)
Roles of DNA/Genes in Controlling Cell Metabolism (pages 444-447, 452 )
Recombinant DNA Technology (Genetic Engineering) (pages 454-463)
Cellular Basis for Cancers (pages 404-412, powerpoint slides 28-36)
Cell Division/Mitosis
After interphase (where the organelles carry on normal functions) the cell enters the stages of the cell cycle. These are mitosis and cytokinesis. The right workings of the cell cycle and mitosis are crucial to the growth and repair of tissue.
After interphase (where the organelles carry on normal functions) the cell enters the stages of the cell cycle. These are mitosis and cytokinesis. The right workings of the cell cycle and mitosis are crucial to the growth and repair of tissue.
The phases of mitosis are Prophase, Metaphase, Anaphase, and Telophase.
1. Prophase- chromosomes attach to spindle fibers
2. Metaphase- chromosomes align at the equator
3. Anaphase- chromatids separate into chromosomes that move toward the poles
4. Telophase-nuclear envelopes form around chromosomes and cytokinesis begins (cytokinesis is the division of cytoplasm and organelles after mitosis).
The major differences between mitosis and meiosis are discussed in the following article.
Early Fetal Development
Meiosis produces eggs and sperm with just one member of a chromosome pair. Fertilization occurs with the uniting of both gametes. A new being is then produced.
This image shows the process of meiosis. http://publications.nigms.nih.gov/thenewgenetics/images/ch1_meiosis.jpg
Meiosis begins fetal development.
Role of Genes/Chromosomes in Inheritance
Meiosis is a part of the development of the sperm and the egg and contributes to genetic diversity. Changes in the chromosome number in the sex cells results in trisomy (one type of chromosome is present in three copies) or monosomy (one type of chromosome is present in a single copy). The syndromes associated with this include trisomy and Down syndrome.
Sex cells that have too few or too many X or Y chromosomes result in Turner, Klinefelter, poly-X, and Jacobs Syndromes.
Chromosomes with deleted, duplicated, inverted, or translocated segments caused by chromosomal mutations result in deletion, Alagille, and certain cancers.
The following site discusses chromosome and gene mutations.
Roles of DNA/Genes in Controlling Cell Metabolism
The nucleus determines the order of amino acids in proteins. (The nucleus is where the DNA is). The proteins control the metabolism of a cell. Chromosomes are formed in the nucleus when cells are dividing. At this time the DNA replicates itself so that the newly created cell is the same as the old cell.
Gene expression is the process that leads to the forming of a protein or another product. The steps required for gene expression are transcription and translation. Transcription takes place in the nucleus and translation occurs in the cytoplasm at the ribosomes.
Recombinant DNA and Technology
Recombinant DNA contains DNA from two or more different sources. For the most part this involves putting a gene from one organism into the genome of another organism.
Bacteria, plants, and animals have all been genetically engineered. Frost resistant strawberries are being developed. Corn, potato, soybean, and cotton plants have been engineered to be resistant to pesticides and herbicides. Mice are being tested through the injection of alleles for human disease. (The mice are then given medications and are studied to see the result of these medications).
This thinkquest site has several links to resources related to genetic engineering.
This diagram shows how genetic engineering produces insulin.
The gene the genetic engineers want to produce insuling may be in a human chromosome.
They use an enzyme to cut the insulin gene out of the chromosome.
Plasmids are then removed from bacterial cells
The plasmids are cut open with an enzyme
A human insulin gene is inserted into each plasmid
The genetic engineers encourage the bacteria to accept the genetically modified plasmids
Bacteria with the insulin gene are then multiplied
Each bacterium will produce a tiny volume of insulin
By culturing the genetically engineered bacteria limitless supplies of insulin may be produced.
Plasmids are then removed from bacterial cells
The plasmids are cut open with an enzyme
A human insulin gene is inserted into each plasmid
The genetic engineers encourage the bacteria to accept the genetically modified plasmids
Bacteria with the insulin gene are then multiplied
Each bacterium will produce a tiny volume of insulin
By culturing the genetically engineered bacteria limitless supplies of insulin may be produced.
Genetic engineering can be used to create other substances such as penicilin or vaccines.
Cellular Basis for Cancers
Characteristics Common to all Cancer Cells
1. lack differentation and do not function
2. enter the cell cycle an unlimited number of times
3. form tumors and do not need growth factors to signal them to divide
4. gradually become abnormal
5. blood vessels grow to support them (angiogenesis)
6. can spread through the entire body (metastasis)
Cancer can be caused by genetics and also environmental carcinogens such as radiation, tabacco smoke, and viruses.
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