Archive for the ‘Glossary’ Category
- 07.23.09
Glossary – 1
DNA
DNA (Deoxyribonucleic acid) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.
DNA Fingerprinting
- 03.03.09
DNA Mutation
A point mutation is a change in the nucleotide sequence of a gene. This can result from an error during replication that is not corrected by the usual repair mechanisms. Under normal circumstances, Adenines and thymines should bind one another as should cytosines and guanines .In a base substition mutations a non-complimentary nucleotide is incporated into the new strand. The resulting altered triplet may code for a different amino acid or even a stop codon. Here we see four codons and their corresponding amino acids. A change within the second triplet results in a change in the amino acids. None of the other amino acids are affected. Insertions and deletions result in frame shift mutations. The insertion of an extra nucleotide not only affects the triplet it is part of but all subsequent triplet thus drastically altering he protein product. The result is similar if the nucleotide is deleted.
- 02.04.09
Composition & Structure of DNA
What is DNA?
Deoxyribonucleic Acid (DNA)
A. What is DNA?
B. Composition and Structure of DNA
- What is DNA?
(Prof. James Watson, Nobel Laureate-1962)
Burning question is how it could work. How could even a giant molecule like this retain all specification, say no, and more personally, how could a molecule instruct onto billions of cells to do their exact function, whether it would be the tip of a trunk or the lens of an eye?
Let us take the first question. What about DNA? We have mentioned it before, but we really need to get into it now. DNA is a long molecule that resides from the most part in the nucleus. DNA is basically a linear chain of 4 bases. They are:
- Adenine
- Thymine
- Cytosine
- Guanine
But we usually just refer to them as A, T, C, and G.
This chain is a code for everything that goes on in your body. The term “coding for” is often used when we speak of a piece of DNA that codes information for a certain set of product or activity. When DNA carries the information necessary to make a protein molecule, we say it “codes for” a certain protein.
How exactly DNA “codes for” protein will be made clear when we talk about protein synthesis.
The Morse code has only three symbols – dot, dash, and space. But these three can convey any message from man to man. DNA, with its four symbols, can convey any possible information from cell to cell.
So, DNA is made of a string of bases. It is the code for proteins, almost everything in your body, and it hangs out in the nucleus of your cells, as well as in the chloroplast and mitochondria.