In biology, a<unk>  (from genos (Greek) meaning<unk> ration or birth or gender) is a basic unit of heredity and a sequence of nucleotides in DNA that encodes the synthesis of a<unk>  product, either RNA or protein. During<unk>  expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of<unk> s to an organism's offspring is the basis of the inheritance of phenotypic traits. These<unk> s make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different<unk> s) as well as<unk> –environment interactions. Some<unk> tic traits are instantly visible, such as eye color or the number of limbs, and some are not, such as blood type, the risk for specific diseases, or the thousands of basic biochemical processes that constitute life.<unk> s can acquire mutations in their sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a protein, which cause different phenotypical traits. Usage of the term "having a<unk> " (e.g., "good<unk> s," "hair color<unk> ") typically refers to containing a different allele of the same, shared<unk> .<unk> s evolve due to natural selection / survival of the fittest and<unk> tic drift of the alleles. The concept of<unk>  continues to be refined as new phenomena are discovered. For example, regulatory regions of a<unk>  can be far removed from its coding regions, and coding regions can be split into several exons. Some viruses store their genome in RNA instead of DNA and some<unk>  products are functional non-coding RNAs. Therefore, a broad, modern working definition of a<unk>  is any discrete locus of heritable, genomic sequence which affect an organism's traits by being expressed as a functional product or by regulation of<unk>  expression. The term<unk>  was introduced by Danish botanist, plant physiologist and<unk> ticist Wilhelm Johannsen in 1909. It is inspired by the Ancient Greek: γόνος, gonos, that means offspring and procreation.
Gene
Clone 
Genome 
TRNA 
Locus
RNA Biology
Nuclear gene
Endotype