Cells, DNA, Proteins and Traits



Four bases are found in DNA. These are Adenine, Guanine, Cytosine, and Thymine.

The physical appearance or characteristics of an individual are determined by its genetic material but the environment is also important for some traits. Each trait is determined by one or more genes.

A gene is a segment of DNA that codes for a product. It is the sequence of bases in that segment that is important. Human beings have approximately 20,000 genes. The sequence of bases determines what proteins will be produced. These proteins serve various functions in the cell. 


The environment also plays in role in determining the appearance i.e. it also influences some traits. For example, irrespective of genes they carry, children who are malnourished cannot grow normally.

There are two main implications of this:

  • We can predict what an organism will look like from its DNA (genes): We can analyze DNA to screen for genetic differences between individuals. We can also determine what genes individuals carry directly from their DNA even before those genes are expressed.
  • We can also alter the appearance of an organisms by directly changing its DNA: We can control the traits of an organism by inserting new genes or even by shutting down specific genes.