What is DNA?
Deoxyribonucleic acid (DNA) is a long molecule that contains an organism’s entire genetic code. Every cell in the body contains two identical strands of DNA, and this DNA contains the “instructions” (genes) needed to create and run every part of the body. DNA directs the overall appearance, health, and actions of the entire animal. All inherited traits are transmitted from an animal to its offspring in the DNA.
Where is DNA located in the body?
DNA is primarily located in the nucleus of each cell, where it is contained in structures known as chromosomes. The nucleus is a large area in the center of the cell and it controls the cell’s activities. Chromosomes are thread-like structures inside the nucleus, and they contain DNA bound tightly with proteins that help the DNA keep its structure. In addition, a small amount of DNA is in the mitochondria, which is a part of the cell responsible for the cell’s energy production.
What are the components of DNA?
DNA is composed of four chemical compounds called bases: adenine (A), guanine (G), cytosine (C), and thymine (T). These bases are the basic units of DNA. The order in which the bases are arranged creates an instruction code for the cells to follow, just like the order of letters form words.
Each DNA base typically pairs with another base: A and T always pair together, while C and G always pair together. These base pairs come together like the rungs of a twisted ladder. The outside of the ladder is composed of sugar and phosphate molecules, which provide external support, while base pairs bridge the gap between these two external strands. This shape is called a double helix.
How does DNA control an animal’s appearance and health?
You can think of DNA as a library of instruction books in the nucleus of each cell. When needed, those instructions are sent to the “manufacturing plants” in the cell to create proteins, the building blocks of life. Rather than move the whole library, the cell “photocopies” sections of DNA to move around. The copies are called mRNA (messenger ribonucleic acid). RNA is taken from the nucleus to specific areas of the cell, where it shows which proteins to make. These proteins are responsible for functions in the cell and throughout the body, many acting as enzymes that regulate various cell and body reactions.
How does a cell make DNA?
The paired nature of A/T and C/G bases allows for the duplication of DNA. When a cell needs to replicate its DNA for cell reproduction, special enzymes come in and “unzip” the DNA double-helix structure. When the DNA is unzipped, there are two single strands of DNA, each with exposed base pairs.
Each strand of DNA can then act as a template for duplicating a new strand of DNA. Each exposed A attracts a T, each exposed T attracts an A, each exposed C attracts a G, and each exposed G attracts a C. A new sugar and phosphate backbone is built along the exposed edge of each DNA molecule. This process creates two identical new strands of DNA; one of these strands can be passed to each cell during cell division (mitosis).
How much DNA is in a cell?
Dogs, cats, and humans have approximately 2.5 to 3 billion base pairs in their DNA, comprising about 20,000–25,000 individual genes. Not all of a cell’s DNA codes for protein sequences; many of the instructions contained in DNA are used for replication, scaffolding, and other functions.
How can the information in DNA help us make breeding decisions?
DNA tests allow pet owners to make educated decisions about breeding. These tests allow us to examine an animal’s DNA to see whether they carry certain genetic codes that cause disease. If a dog is found to carry such a genetic code, it may be best not to breed them to prevent that disease in their offspring.
Are there any other uses for DNA?
In addition to genetic testing for diseases and traits, DNA testing may be used to determine an animal’s ancestry. This testing may be beneficial for owners who would like further information about the heritage of their mixed-breed pets.
