Gene Interactions
When the expression of a single trait is influenced by two or more different non-allelic genes, it is termed as genetic interaction. According to Mendel's law of inheritance, each gene functions in its own way and does not depend on the function of another gene, i.e., a single gene controls each of seven characteristics considered, but the complex contribution of many different genes determine many traits of an organism.
Gene Expression
Gene expression is a process by which the instructions present in deoxyribonucleic acid (DNA) are converted into useful molecules such as proteins, and functional messenger ribonucleic (mRNA) molecules in the case of non-protein-coding genes.
How many types of promoters are there?
Promoters are DNA sequences that determine where the gene transcription by RNA polymerase begins. That means promoter is the region where transcription of genes is initiated. Promoter sequences are usually located directly upstream on the DNA or at the 5’ end of transcription initiation site of genes. They can be about 100-1000 base pairs long.
There are three major types of promoters depending upon the level of gene expression and specificity: constitutive, inducible, and specific promoters.
- Constitutive promoters: These promoters facilitate the expression of the gene in all the tissues regardless of surrounding environment and development stage of organism. Constitutive promoters are unregulated promoters that allow for the continual transcription of genes associated with them. These promoters can turn on the genes in every cell, all the time, throughout the life of the organism. Some examples of constitutive promoters are: opine promoters, CaMV 35S promoter, rice actin-1, etc.
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