06. Genetics [DEFINITIONS] Flashcards
Character
A heritable feature that varies among individuals of a population such as hair colour or eye colour is called a character.
Trait
The heritable variants of a character in an organism, such as brown/blond hair or blue/brown/black eye colour in humans are called traits.
Gene
The gene is the basic unit by which genetic information is passed from parent to offspring.
Locus
A locus is a fixed position on a chromosome. A DNA sequence residing usually at a specific locus on a particular chromosome contributes to the development of one or more traits by coding for specific proteins or peptides.
Alleles
Alleles are alternative versions of genes that reside on the same locus of different chromosomes. (they vary in their sequence of nucleotides?)
Homozygous
The condition of having two identical alleles for a given gene is known as homozygous state.
Heterozygous
Having two different alleles for a given gene is referred to as heterozygous state.
Phenotype
A phenotype is brought about by the interaction between genotype of the individual with its environment
Genotype
The genetic make up, or set of alleles of an organism is known as its genotype. (could be either homozygous or heterozygous?)
Dominant Allele
At heterozygous state, the allele which determines the organism’s phenotype by masking the expression of the other is referred to as the dominant allele.
Dominant Trait
The trait produced by the dominant allele is known as the dominant trait
Recessive Allele
The allele which doesn’t exhibit any noticeable effect on the organism’s phenotype at heterozygous state is referred to as the recessive allele.
Recessive Trait
The trait hidden on the recessive allele is the recessive trait. (However, they express their trait when they exist in homozygous state.)
Contrasting Traits
Mendel tracks the characters that only occurred in two distinct, contrasting phenotypic forms (such as tall stem length vs short stem length / purple flower colour vs. white flower colour) Such traits are contrasting traits.
Pure breeding / True breeding
Pure breeding plants are obtained by self-pollinating over many generations, producing only the same variety as the parent plant.
Pure Lines
The uniform lines produced from the self-fertilization of pure breeding varieties over many generations are called pure lines.
Hybridization
The mating or crossing of two pure-breeding varieties with contrasting traits is called hybridization.
P generation (Parental Generation)
The parental generation is referred to as P generation.
F1 Generation (First Filial Generation)
Plant progeny resulted from hybridization events are referred to as the F1 generation
F2 Generation (Second Filial Generation)
The progeny that results from the self or cross pollination between F1 generation plants are known as F2 generation.
Monohybrid
An organism that is heterozygous with respect to a single gene of interest resulting from a cross between parents having homozygous condition for different alleles of specific gene is referred to as a monohybrid.
Monohybrid Cross
A breeding experiment conducted between two organisms with heterozygous condition for a specific character is referred to as a monohybrid cross.
Dihybrid
A heterozygous organism with respect to two genes of interest resulting from a cross between parents having homozygous conditions for different alleles of two specific genes is referred to as a dihybrid.
Dihybrid Cross
The breeding experiment conducted between two organisms with heterozygous conditions for two specific characters is known as a dihybrid cross.
Test Cross
Breeding an organism having an unknown genotype for a specific dominant trait with an organism having homozygous recessive condition for the same specific trait is called a test cross.
Mendel’s Law of Segregation / Mendel’s 1st Law in inheritance
During the formation of gametes, the alleles for a heritable character are separated and get in to each of the gametes formed. This is known as Mendel’s Law of Segregation.
