Chromosomes+and+genes.+Page+44+and+45.+Initial+terms

It is the part of Biology which studies the transmission of the characteristics from one individual to its descendants. A gene is a sequence of DNA bases that specify the order of amino acids in a protein. A gene may be made up of hundreds to thousands of DNA bases. Genes are responsible for hereditary characteristics.  The alleles for a trait occupy the same locus or position on homologous chromosome and thus govern the same trait. However, because they are different, their action may result in different expressions of that trait.
 * Genetics **
 * Gene **
 * Allele **
 * Possible alternatives of a gene which control a particular trait. **

Locus (plural loci)
The place each gene occupies in the chromosome

Chromosomes  that are paired during meiosis. Such chromosomes are alike with regard to size and also position of the centromere. They also have the same genes, but not necessarily the same alleles, at the same locus or location.
 * __Homologous ____chromosomes __**

An organism which has two copies of **the same allele** for a trait, for example AA or aa. An individual may be homozygous dominant ( AA) or homozygous recessive (aa)
 * Homozygous or Pure-breeding **

An individual which has **two different alleles** for a trait. E.g. Aa
 * Heterozygous or Hybrid **

**<span style="font-family: 'Arial','sans-serif';">Phenotype **
==**<span style="font-family: 'Arial','sans-serif';">It is the set of traits (characteristics) observed in one individual, which depend on the genotype and also on the environmental conditions, i.e. interaction of the genotype and the environment **==