In this section, we’re going to introduce you to DNA, genes, and chromosomes. This will help you understand the building blocks of your genetic makeup.
Now, we’re going to introduce you to DNA, genes, and chromosomes.
2.A — WHAT IS DNA?
Genetic material is made of DNA. DNA is a long string of 4 different chemicals represented by letters.Imagine a language with an alphabet containiing only 4 letters.
These four letters are strung together in different combinations or “sequences.”
2.B — WHAT IS A GENE?
Specific sequences of DNA are called genes. These sequences are read and understood by the cells in our body.
If we think of DNA as a cookbook, then a gene is like a recipe in that cookbook. There are over 20,000 different genes. Wow! That’s a lot of recipes!
Genes give instructions for our bodies to make proteins, just like recipes give instructions to make different cookies.
Proteins make up our bones, blood, muscles, skin, hair and everything else our bodies need to grow, develop and function.
2.C — WHAT IS A CHROMOSOME?
Genetic information is not limited to just the genes. DNA also includes what is in between the genes. There is a lot of this “filler” DNA. Genes, and the DNA between them are tightly wound together and organized into structures called chromosomes.
Each cell of our body contains chromosomes. Chromosomes are housed in the center of each cell, also known as the nucleus. You can actually see the chromosomes through a microscope.
Most individuals have 46 chromosomes, or 23 pairs. For every pair of chromosomes, one chromosome comes from our mom and one from our dad.
Chromosome pairs are numbered 1 through 22, and the 23rd pair is called the sex chromosomes. These are known as the X and Y chromosomes and determine sex at birth. Usually, females have two X chromosomes and males have an X and a Y chromosome.
Except for genes on the sex chromosomes, we inherit two copies of every gene, one from each parent. This is why we have traits from our mom and our dad.
A karyotype is a picture of the chromosomes ordered by size and followed by the sex chromosomes.