Genetics in Biomedical Research

The study of DNA has been the second main thrust of molecular biology, paralleling analysis of protein structure and function. Proteins make up most cellular components DNA contains the instruction set for when and how to make them. The other important function of DNA is to serve as the structural basis of inheritance. 

The DNA base pairs described earlier in this chapter are linked together in long chains. There are four nucleotide bases linked together in extremely long chains, coiled up and bound with proteins to form chromosomes. The information content of DNA is mainly contained in the order of these base pairs, the DNA sequence. DNA is the structure by which individual traits are transmitted from generation to generation. The linear code of four letters is analogous in some ways to the linear code of O s and l s in computer software, which also instruct hardware to carry out functions and can be copied faithfully for transmission. 

Genes were expressed (ie., produced a product) only at certain times, in certain tissues, and in certain amounts. Uncovering such complexities made it difficult to directly map inheritance, with its discrete particles of inheritance, to the exquisitely complex processes governing expression of genes. The complexity of molecular genetics was reflected in the changing face of human genetics. 

Geneticists have been constructing maps of chromosomes since 191.3, when Alfred Sturtevant found traits that were inherited together and inferred their corresponding genes were therefore located on the same chromosome. Geneticists labored for decades to construct maps of the 

CF is the most common seriously disabling single gene defect among Caucasian populations. It is a recessive condition, present only when a child inherits defective copies of a gene on chromosome 7 from both parents. CF affects approximately 1 in 3,500 live births in the United States 1 in 30 Americans has one copy of a CF mutation gene, but most are unaffected because it takes both copies of the gene to cause 

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