Genetics and heredity

Genetics

Genetics

It is the branch of biology that deals with the study of heredity and variation of inherited characteristics

Heredity

It is the passing on of traits from parents to offspring by means of genes on chromosomes

Gene

It is a unit of hereditary material located on a chromosome which control characteristics or traits

Locus

It is defined as the relative position of a gene on a chromosome

Carrier

Refers to an individual who is heterozygous for a trait that only shows up in the phenotype of those who are homozygous recessive

Chromosomes

A thread-like structure of nucleus acids and proteins found in the nucleus of living cells, carrying genes/genetic information

Chromosome number

It is the total number of chromosomes in a somatic cell fixed for any particular species

Genome

refers to the full genetic complement of an individual.

Dominance

Is a relationship between alleles of one gene in which the effect of one allele is expressed over the other.

Co-dominance

Occurs when both alleles in heterozygous individual are equally expressed

Dominant allele

Is one of the alternative forms of a gene which mask the effect of the other

Incomplete dominance

Incomplete dominance

is a form of Gene interaction in which both alleles of a gene at a locus are partially expressed, often resulting in an intermediate or different phenotype

Recessive allele

An allele that is masked in the phenotype by the presence of a dominant allele

DNA(Deoxyribonucleic acid)

A large organic molecule that stores the genetic code for the synthesis of proteins

Genotype

The genetic complement of an organism, in terms of particular set of alleles it possesses

Phenotype

Refers to the physical characteristics of an organism determined by both the genotype and the environment

Heterozygous

Is defined as a cell or organism that contains two different allele for any one gene

Homozygous

Is defined as a cell or organism that contains two identical allele for one gene

Hybrids

Offspring that are the result of mating between two genetically different kinds of parents

Hybrid vigour

This is the production of new varieties within a species, which are better adapted to the environment as a result of outbreeding non related members of a species

Polygenic trait

An inherited trait that is determined by genes at two or more loci.

Purebred

Offspring that are the result of mating between genetically similar kinds of parents

Monohybrid cross

Is a genetic cross using a single trait with two allele

Dihybrid

A cross involving two individuals that differ in two pairs of contrasting character

F1(first filial generation)

the offspring produced by crossing the parental generation

Gene pool

Is the collection of different genes or alleles within an interbreeding population

Gene flow

Is a concept in population genetics to refer to the movement of genes or alleles between interbreeding of individuals of adjacent population

Genetic drift

The random change in the frequency of alleles in a population variation in relative frequency of different genotypes in a population owing disappearance of particular genes

F2(second filial generation)

the offspring produced by crossing the f1 generation

Test cross

The cross of an individual to a homozygous recessive parent;used to determine if the individual is homozygous dominant or heterozygous

Backcrossing

Is a crossing of a hybrid with one of its parents or an individual genetically similar to its parent, in order to achieve offspring with a genetic identity which is closer to that of the parent