June 26, 2013
What is DNA?
Hi, my name is Emerald Robinson, and in this “What Is” video, we’re going to examine the so-called “stuff of life”: DNA.
DNA is a nucleic acid that carries all of the genetic material necessary for cells to develop and function. The letters D-N-A stand for deoxyribonucleic acid. DNA floats freely in the cytoplasm of bacterial cells, and is found in the nucleus of plant, animal, and fungal cells.
DNA is made of sub-units called “nucleotides.” Each nucleotide has a phosphorous group, a sugar, and a special nitrogen-containing molecule called a base. There are four of these bases in DNA: adenine, guanine, cytosine, and thymine. Cytosine and guanine combine, just as adenine and thymine combine to form units called base pairs.
When the nucleotide sub-units are put together, they form a structure that looks like a twisted ladder. Called a double helix, the phosphorous and sugar molecules make the rails of the ladder, and the base pairs make the rungs. The double helix model was suggested by scientists James Watson and Francis Crick in 1953, and it earned them a Nobel Prize.
DNA acts as a “blueprint” for the cell because it contains the codes a cell needs to grow and function. These codes come from specific segments of DNA called “genes.” DNA, and the genes that make it up, are passed from parent to offspring, so the information carried on your genes determines who you are. The result of a gene being expressed is often a protein. These proteins ultimately determine traits like blood type, hair or fur color, and likelihood of getting certain diseases.
DNA is unique because it replicates itself, making it essential for cellular life. When cells divide, each new cell needs an exact copy of the DNA present in the old cell. This copied genetic material allows all modern living things to function, grow and reproduce.