Genetic terminology, Biology

GENETIC TERMINOLOGY

(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.

or

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
Give the introduction to evaluation of patient clinical examination ? A careful physical examinations is a very important for assessing the cardiovascular system and after prov

Ingestion of Foreign Bodies: As we know  that small children are curious and  innocence children are notorious for inserting various object into their orifices like mouth, nos

Enzyme Synthesis Nitrate assimilating system in general is known to show increase in nitrate uptake system and nitrate reductase system in the presence of nitrate. In other wo

Determine the term - Test-retest reliabilities The test manual reports reliability data. Test-retest reliabilities for the 13 main scales range from .78 to .96. The problem of

Explain about the Health Economics and Economics of Malnutrition? In the earlier units on nutritional problems, we learnt that there are many causes of malnutrition, socioecono

Determine the Food Sources of Vitamin A? Vitamin A or retinol performed vitamin A), as you may already know, is found only in foods of animal origin, such as milk, cheese, crea

In about 80 per cent of ARF patients, ASO titre is significantly raised. ASO titres vary with age, geographical area and other fevers, which influence frequency of streptococcal in

Q. What is the binding between two amino acids called? The chemical bond between two amino acids is called a peptide bond.

AMITOSIS This  is  direct  cell division  in which  the genetic material is not duplicated and  hence its distribution  to the daughter cells  is not  precisely half  and half,

How are gases exchanged in sponges? The gas exchange in sponges occurs by diffusion from the external to the cells that absorb molecular oxygen and release carbon dioxide.