WHAT ARE GENES?
Genes are segments of DNA inherited from biologic parents. Most of our genes exist in pairs, one inherited from each parent. Genes act as instructions to make molecules called proteins. Most genes are the same in all people, but some genes are slightly different between people. Alleles are forms of the same gene with small differences in their sequence of DNA bases. These small differences contribute to each person’s unique physical features.
Genes are long molecules composed of the chemical DNA and are found in the nucleus of each cell. Genes perform two important functions. Firstly, each gene is the recipe, blueprint, or code for building a particular protein within the cell. Because proteins do all their work inside a cell, a mistake in the blueprint for any one of these proteins may have serious consequences for the functioning of that cell. Early-onset dystonia is caused by a mistake in the gene that contains the code for the protein called torsinA. The exact role of torsinA in brain cells is not known. Secondly, genes are the material of inheritance copied and passed from parent to child they ensure that offspring arise from a combined set of blueprints from the parents. Genes are linked together to form even longer structures known as chromosomes. Almost every human cell contains exactly 46 chromosomes or 23 pairs. Each chromosome comprises hundreds or thousands of genes strung together. The DYT1 gene is located on t
Genes are working subunits of DNA. DNA is a vast chemical information database that carries the complete set of instructions for making all the proteins a cell will ever need. Each gene contains a particular set of instructions, usually coding for a particular protein. DNA exists as two long, paired strands spiraled into the famous double helix. Each strand is made up of millions of chemical building blocks called bases. While there are only four different chemical bases in DNA (adenine, thymine, cytosine, and guanine), the order in which the bases occur determines the information available, much as specific letters of the alphabet combine to form words and sentences. DNA resides in the core, or nucleus, of each of the body’s trillions of cells. Every human cell (with the exception of mature red blood cells, which have no nucleus) contains the same DNA. Each cell has 46 molecules of double-stranded DNA. Each molecule is made up of 50 to 250 million bases housed in a chromosome. The DNA
Inside every cell of each living thing (plant or animal) are sets of instructions called genes. The genes provide the instructions on what is the plant or animal, what it looks like, how it is to survive, and how it will interact with its surrounding environment. The genes are strung together in long stands of material called deoxyribonucleic acid (DNA) and these long strands are called chromosomes. Most living things have pairs of chromosomes (one from each parent), though they may have a different number of chromosomes from another living thing. For example, humans have 23 pairs of chromosomes and the fruit fly has 4 pairs. Each gene is made up of long combinations of four different nucleotide bases. It is the various combinations of the nucleotide bases that determine everything about a living creature. The four nucleotides are called: • adenine(A), • cytosine (C), • guanine (G), and • thymine (T). The gene for green eyes might have this nucleotide sequence. AAACCGGTTTTT The gene fo
Genes are spiraled, threadlike particles made of DNA (deoxyribonucleic acid). DNA contains the instructions for building proteins. And proteins control the structure and function of all the cells that make up your body. Genes and the important information they carry are packaged inside chromosomes. Most cells in your body have two copies of every chromosome and, therefore, two copies of every gene: one from your mother and one from your father. Think of your genes as an instruction manual for cell growth and function. Abnormalities in the DNA are like typographical errors. They may provide the wrong set of instructions, leading to faulty cell growth or function. In any one person, if there is an error in a gene, that same mistake will appear in all the cells that contain the same gene. This is like having an instruction manual in which all the copies have the same typographical error.
