08-23-2013, 04:59 AM
Functional genomics may be defined as determination of the function of a gene product. This includes answers to the questions, how is a gene expressed, how is its product related in sequence and structure to products of other genes of the same organisms, and how does it interact with them? These questions can be answered by studying the following:
(i) When and where particular genes are expressed (expression profiling)
(ii) The functions of specific genes by selectively mutating the desired genes, and
(iii) The interactions that take place among proteins and between proteins and other molecules.
These are the questions that molecular geneticists had been investigating all along. But while they were looking at one gene at a time, functional genomics attempts to examine all the genes present in the genome in one go. Therefore, the techniques used in functional genomics enable high throughput analyses that enable a very rapid accumulation.
1. Expression profiling
2. Transcriptome
The full complement of RNA molecules produced by the genome is, usually, referred to as transcriptome. In case of eukaryotes, a single gene can produce more than one type of mature mRNA by a phenomenon called alternative splicing. In alternative splicing, the splicing occurs in two or more different but well-defined patterns. In each splicing pattern, a defined set of exons in joined together to yield a functional RNA molecule. The net effect of alternative splicing is the generation of a large number of different proteins from a relatively smaller number of genes. If each human gene was alternatively processed to yield an average of 3 proteins, the estimated 35,000 human genes would produce 105,000 different proteins. Thus, the transcriptome is bound to be much more complex, i.e., variable, than the transcribed portion of the genome.
This is because each RNA transcript would generate multiple mRNAs. In addition, none of the tissue of a multicellular organism will express all the genes, and genes expressed in one tissue will differ from those in another tissue. In other words, the transcriptome obtained from one tissue will differ in some respects from that obtained from another tissue. Therefore, it is customary to refer to the transcriptomes as ‘human brain transcriptome’, ‘mouse liver transcriptome’ etc.
3. DNA Arrays
4. Gene Function determination
5. Protein Interactions
(i) When and where particular genes are expressed (expression profiling)
(ii) The functions of specific genes by selectively mutating the desired genes, and
(iii) The interactions that take place among proteins and between proteins and other molecules.
These are the questions that molecular geneticists had been investigating all along. But while they were looking at one gene at a time, functional genomics attempts to examine all the genes present in the genome in one go. Therefore, the techniques used in functional genomics enable high throughput analyses that enable a very rapid accumulation.
1. Expression profiling
2. Transcriptome
The full complement of RNA molecules produced by the genome is, usually, referred to as transcriptome. In case of eukaryotes, a single gene can produce more than one type of mature mRNA by a phenomenon called alternative splicing. In alternative splicing, the splicing occurs in two or more different but well-defined patterns. In each splicing pattern, a defined set of exons in joined together to yield a functional RNA molecule. The net effect of alternative splicing is the generation of a large number of different proteins from a relatively smaller number of genes. If each human gene was alternatively processed to yield an average of 3 proteins, the estimated 35,000 human genes would produce 105,000 different proteins. Thus, the transcriptome is bound to be much more complex, i.e., variable, than the transcribed portion of the genome.
This is because each RNA transcript would generate multiple mRNAs. In addition, none of the tissue of a multicellular organism will express all the genes, and genes expressed in one tissue will differ from those in another tissue. In other words, the transcriptome obtained from one tissue will differ in some respects from that obtained from another tissue. Therefore, it is customary to refer to the transcriptomes as ‘human brain transcriptome’, ‘mouse liver transcriptome’ etc.
3. DNA Arrays
4. Gene Function determination
5. Protein Interactions
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