Genes Flashcards
What is a gene
A segment of DNA (located on a chromosome) that is in control of offsprings traits/characteristics. Genes also code for proteins
What is an allele?
Alleles are pairs or series of genes on a chromosome that determine the hereditary characteristics. An example of an allele is the gene that determines hair color.
What is a chromosome?
a threadlike structure made of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
What is a recessive allele?
A recessive allele is a variety of genetic code that doesn’t create the phenotype if a dominant allele is present. A recessive allele will only be apparent if it’s homozygous recessive.
What is a dominant allele?
A dominant allele is a variation of a gene that will produce a certain phenotype, even in the presence of other alleles. It masks the characteristic of the recessive allele
What is a genotype?
The genotype is the genetic makeup of cell which determines its characteristics
What is a phenotype?
The phenotype is the physical characteristics of an organism derived from the genotype and its interaction with the environment.
Define homozygous?
Having two identical alleles of a particular gene or genes (AA, aa).
Define heterozygous?
Having two different alleles of a particular gene or genes (Aa, Nn).
What is Pure breeding?
A group of identical individuals that always produce offspring of the same phenotype when intercrossed.
This ensured that when Mendel crossed two plants with differing traits, there were no other factors contributing to the outcome of the cross.
Define Monohybrid cross
A monohybrid cross is a mating between two parents in which only one pair of genes, that is one pair of contrasting characteristics is considered (eye colour - blue/brown, hair colour - black/blonde).
Define Dihybrid cross?
A mating between two parents in which two pairs of contrasting characteristics are considered (tall purple flower, short white flower).
Define Hybrid
Hybrids are organisms that result from crosses of parents having different expressions of the same trait (plant seeds: wrinkled or smooth)
Define Incomplete Dominance
The dominant allele is not completely expressed when the recessive allele is around. Resulting in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles (i.e. red + white = pink)
Define Codominance
Both alleles are fully expressed resulting in offspring with a phenotype that is neither dominant nor recessive (black + white cow = black and white spotted cow)
