Genetic terminology, Biology


(i)         Gene - Mendel used the term factor for a gene. A gene is the unit of DNA responsible for the appearance and inheritance of character.

(ii)         Allele - It refers to the alternative forms of a gene which control the same character and located at the same locus in the homologous chromosomes.

(iii)        Gene Locus - It is the region on chromosome representing a single gene. The alleles of a gene are present on the same gene locus on the chromosome.

(iv)        Heterozygous - The prefix hetro means 'different' and zygous means 'a pair'. The organism in which both the factors of a character are unlike is said to be heterozygous or hybrid. Such organisms do not breed true on self fertilization eg. Tt.

(v)         Homozygous - The prefix homo means 'the same' and zygous means 'a pair'.The organism in which both the factors of a character are similar is said to be homozygous or genetically pure for that character. It gives rise to offsprings having the same character on self breeding. e.g TT or tt.

(vi)        Dominant and Recessive - A heterozygote possesses two contrasting factors or alleles but only one of the two is able to express itself, while the other remains hidden. The factor which gains expression in F hybrid is known as dominant factor while its allele is unable to express itself in presence of the dominant factor is recessive factor.

(vii)        Genotype - It is the genetic constitution of an organism which determines the characters.

(viii)       Phenotype - It is the appearance of an individual.


Phenotype of an individual refers to the expressed or observable structural and functional traits produced by interaction of genes and environment.

Note :- The term Genotype and Phenotype were coined by Johanssen.

(ix)        Pureline - Generations of homozygous which produce offsprings of only one type i.e. they breed true for their phenotype and genotype.

(x)        Genome - Sum total of genes in the haploid set of chromosomes and inherited as unit from parents to offspring.

(xi)            Genepool - All the genotypes of all organisms in a population form the gene pool.

Posted Date: 10/10/2012 3:32:34 AM | Location : United States

Related Discussions:- Genetic terminology, Assignment Help, Ask Question on Genetic terminology, Get Answer, Expert's Help, Genetic terminology Discussions

Write discussion on Genetic terminology
Your posts are moderated
Related Questions
Do all genetic diseases result from alteration in the number of chromosomes of the cells? Besides aneuploidies there are other genetic diseases, other chromosomal abnormalities

Energy Flow - Ecosystem Our world is a solar-powered system, and green plants are the entry gates of energy into ecosystem. The total incoming solar energy, only a very small

Q. How do the potassium and sodium ions maintain the resting potential of the neuron? The plasma membrane of the neuron when at rest maintains an electric potential difference

What is Intracardiac Repair of Tetralogy of Fallot ? Technique : The essential steps are: (I) relief of right ventricular outflow obstruction, and (2) closure of ventricular

DEVELOPMENT OF PSYCHIATRIC NURSING IN OTHER COUNTRIES: Although the scientific findings rejected the belief that mental disturbance was the devil's work, the earliest asylums

Protozoans ingest food by phagocytosis, and consequently, the ingested food is surrounded by a plasma membrane creating a food vacuole, or phagosome. Digestion does not start until

Veterinary medicine Veterinary medicine is a branch of science that deals with diagnosis, treatment and control of diseases in animals such as livestock, domesticated animals,

A species of trilobite was found in the fossil record. At its first appearance, it is similar to an ancestor species but differs from the ancestor in several key characteristics. I

Are the xylem and the phloem made of living cells? The cells that constitute the xylem ducts are dead cells killed by lignin deposition. The cells of the phloem are living

Identify three ways that bacteria can be transmitted from person to person. Diseases affecting nerves contain botulism and tetanus; diseases affecting the intestine include sa