Explain what genes are, highlighting their relationship to DNA and chromosomes.

Expert Answers

An illustration of the letter 'A' in a speech bubbles

Let's start with DNA. DNA is an organism's genetic code. In humans, that genetic code is 3 billion lines of code long. If you read one line of code per second for 24 hours per day, 365 days per year, it would take you nearly 100 years to read the entire code. The code itself is only composed of four different "letters." Those letters are A, T, C, and G. The order of those letters is different across the 3 billion lines of code that each person has. It is also different between every individual person.

A person's DNA sequence is broken into 46 different "chunks" or chromosomes. This means that your chromosomes are made of sections of DNA. A gene is a section of a chromosome. Therefore, a gene is also a section of DNA. A gene is the section of a chromosome that codes for a particular trait. Chromosomes each carry many genes. A single chromosome can carry information for hair color, eye color, ear appearance, and many other traits. Different species have different numbers of chromosomes.

An analogy for the relationship between DNA, chromosomes, and genes might help. Let's use a library. The entire library carries a lot of information, just like an entire strand of DNA carrying all the information necessary to produce a person. To make things easier to find, the library divides its books and knowledge into different sections. That's like your DNA being divided into chromosome sections. Then within each library section are specific books. The books are specific pieces of information, similarly to how genes are specific pieces of information within a chromosome.

Approved by eNotes Editorial Team