Levels of Organization Image Map

How do you define sex? Scientists define sex as the exchange of inherited traits.  

Man Lifting Weights ImageOver a hundred years ago, there was a raging debate over whether we could inherit things that happen to us in our environment. For example, if your parents had lifted weights and became super strong, would they have passed that on to you when you were born? The answer is a definite NO. What can be passed on to children is how much capability you will have for responding to the lifting of weights. 

In cells, the instructions begin in the genes, which are found in the structures called chromosomes inside the cell nucleus. Chromosomes contain the DNA, and specific sequences of base pairs code for specific amino acids, which  are the building blocks of proteins. 

The beginning of our modern understanding of the coding scheme began in 1857 with the experiments of Gregor Mendel. Click here for a complete outline of the key historical events. Story Time tells about Gregor and how he came to be so famous.

Relation of a Plant to its Cells to its Genes
Relation of a Plant to its Cells to its Genes

Mendel's tedious experiments led him to some brilliant conclusions in the form of two principles that later became known as the laws of heredity. 

To really understand this, let's explore: 

Nature of Genetic Coding

 

Web Sites You Might Want to Check Out:

Animated primer on the basics of DNA, genes, and heredity: http://www.dnaftb.org/dnaftb/ 
The Human Genome project: http://www.ornl.gov/TechResources/Human_Genome/home.html
Tutorial: http://library.thinkquest.org/19037/ebasics.html
Gene sequences for human chromosomes 5, 16, and 19: www.doe.gov/news/releases00/aprpr/pr00104.htm
The "gene school", written by students: http://www.netspace.org/MendelWeb/MWref.html
Mendel Web, a popular site on classic genetics: http://www.mendelweb.org/
Web site on Mendelian Genetics: http://www.biology.arizona.edu/mendelian_genetics/mendelian_genetics.html


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