Question

What do the following genetic symbol stand for: AA, Aa.

Answer 1

A living organism can be identified on the basis of two important features which is the genotype and other is the phenotype. The genotype is an organism’s set of heritable genes and can be passed from one generation to the other generation. The phenotype is the observable characteristic of an organism.

Complete answer:
-The genes carry hereditary information from generation after generation. The genes carry the traits or expression of a particular characteristic. The genes are often present in the form of one or two or more forms which are known as the allele.
-Allele contains two versions of the same gene character such as dominant allele and recessive allele. The dominant allele is the allele that is able to express itself in the phenotype. It is also known as dominant allele while the other allele which is not able to express freely or get masked by the dominant allele is known as the recessive alleles.
-The set of symbols that is used for the representation of the various genes are known as genetic symbols. Various types of symbols are used to denote or represent the genes or alleles. The symbols are used for the representation of the gene. This is done by using the first one or two letters of the name of the gene. In most of the cases, the upper-case alphabets are used for the dominant alleles while the recessive alleles are represented by the recessive alleles.
-When in a genetic symbol both the letter is of uppercase and consists of the same copies such as AA is referred to as the homozygous dominant for a particular type. Whereas, if both the letters are of small case, the individual is known to be homozygous recessive for that gene. If the genetic symbols contain two different types of alleles, such individuals are known as heterozygous. The genetic symbol Aa represents the heterozygous dominant where ‘A’ is the dominant allele and ‘a’ is recessive allele.

Note: Genes are described as the sequence of nucleotides in the nucleic acids and it encodes for the synthesis of a gene product which is in the form of RNA or protein. They are present in two forms or alleles which is the dominant allele, represented by uppercase letter and recessive allele, represented by lowercase letter. So, AA represents homozygous dominant and Aa is the heterozygous dominant for a particular gene.