How are traits expressed?
Proteins are responsible for expression of traits. They are represented by genotype and phenotype of an individual. Genotype is the genetic constitution of a trait and phenotype is the physical character of a trait.
The DNA contains information which are needed to make the proteins which are essential for growth, development and immunity of body.
DNA determine traits by the order of the nitrogen bases in a DNA molecule. This order is required to make proteins that controls the traits and characteristics of an organism.
Central dogma of molecular biology explained how instructions from DNA flows into proteins, which means how the genes are expressed.
DNA → RNA → protein
Gene expression is defined as the process by which gene is expressed or used for production of functional protein or gene product.
All cells have same in your body has same set of genes, but when cells divide and grow then different cell types are formed that results in different genes expression.
For example, liver cell perform different biochemical duties from nerve cell which means different proteins are made as different genes are expressed. This is because different gene sets of must be turned on and off which means expressed or not in the various cell types.
An organism require different proteins at different places in body and at different times. Genes will be turned on and off in cells according to their need. For example liver cell expresses particular gene and rest of the genes are not expressed, or turned off as they are not needed in liver cells.