DNA is a chain of 4 different units, called base pairs, in various orders. The 4 units that make up DNA are abbreviated A,C,T, and G so that any arbitrary chain made of these units such as AACTGGGTGC is DNA.

DNA stands for deoxyribose nucleic acid; “deoxyribose” is the sugar backbone of the DNA on which the ACTG base pairs are attached, the “nucleic” signifies that the molecule is found in the nucleus of a cell, and “acid” refers to the fact that DNA fulfills the definition of an acid.

DNA generally stores instructions to make proteins that the cell reads to grow or respond to a stimulus. Additionally, DNA sometimes doesn’t code for proteins and has other functions. A chromosome is a very large continuous strand of DNA, in other words it’s a long piece of DNA.

Many pictures of chromosomes have them looking like “X’s, but that’s only when the cell is about to divide. Usually chromosomes just look like a pile of yarn.

Genes are specific sections of a chromosome that code for a protein. The vast majority of the chromosome does not code for proteins. These non-coding regions are used either to control when genes are turned into proteins, to make functional RNA molecules which are similar to DNA, or don’t seem to do anything. So, to summarize, DNA is any molecule with a deoxyribose backbone and the ACTG bases, a chromosome is an actual piece of DNA, and genes are regions of DNA in a chromosome that code for proteins.

Chromosomes are composed of DNA. Genes are also made up of DNA. A chromosome contains many genes, but not all of the DNA in a chromosome is part of a gene. Chromosomes also contain proteins that hold them together that aren't DNA, but these proteins are not part of the genes.

Thank you for your very important question!

A scientist named Richard Dawkins likes to describe the relationship between DNA, genes, and chromosomes in the following way:

Imagine a massive building with many, many rooms. The building is a body, and the rooms are each a cell in that body. Within each room, or cell, there is something like a bookshelf packed with books (the nucleus). Take a book down and open it up. Each letter on the page, and the page is filled with letters, is a C, G, A, or T. These letters run on and on in complex patterns on every page in every book.

These letters represent the four different molecules that make up DNA, and the pattern they are written in is a code that builds and keeps the body running. To stay organized, every now and then there is a special sequence of C, G, A, and T that is like the period to the end of a sentence.

So what is a gene then? A gene is like a chapter in one of the books, it is a given length of DNA that does a specific job, like determining the color of someone’s eyes. Next, bundles of genes near each other form a chromosome, just as a series of chapters form a book.

It turns out that humans have 23 pairs of chromosomes, for a total of 46 “books” that describe how to create the body. Half are from mom and half are from dad. Because of this, no two people (except for identical twins) have quite the same genetic code.

So chromosomes are made of genes, which in turn are made from DNA in the way that books have chapters and chapters have letters.

Biology can be very difficult for a lot of people because there are so many different vocabulary words to keep track of, and genetics can be especially tricky. To simplify these three terms, let’s compare building a cell to building a house. The DNA itself is the paper that the plans are printed on. It contains all of the information on how to build every part of the house, and anyone that wants to build a house has to have blueprints. In humans,every single cell in your body has a complete copy of your DNA even though it may not use every part of it. The cells in your hand have the information on how to build an eye but they will never read that part of the DNA because it is worthless to hand cells.

Each chromosome is a page of the blueprints containing some, but not all of the necessary information. Humans contain twenty-three chromosomes which together have all of the information on how to build us. A gene is the plan on how to build a specific part of the house and is located on a certain part of a specific chromosome. Imagine one gene could be the instructions on how to build the front door which could be found on the top right portion of page five. In humans, a gene will contain the instructions on how to make a specific protein, like the protein that makes a person’s eyes brown. DNA, chromosomes, and genes are all involved in genetics, and refer to different specificities in the genetic code.

Thank you for the question!