Summary Grade 12 - Genetics and Genetic Engineering_Terminology and Definitions

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Genetics and Genetic Engineering: Terminology and Definitions
no Term Terminology / Definition
1 Genetics A branch of biology that studies heredity and variation in organisms.
The unit of heredity transmitted in the chromosome which controls the development of
2 Gene
the characteristics.
3 Zygote The resulting cell after fertilization has occurred.
4 Locus This is the exact position or location of a gene on a chromosome.
A pair of genes that are located at the same point on each of the two homologous
5 Alleles chromosomes and represent a specific trait – one from the father and one from the
mother.
 Homo = same and zygous = zygote.
6 Homozygous  When two alleles of a pair of genes are the same for one trait e.g. both alleles are
for red flowers, the cross will result in a pure breed for red.
 Hetero = different and zygous = zygote.
 When two alleles of a pair of genes are different for a trait e.g. one of the alleles is
7 Heterozygous
for red flowers and one is for white flowers, the cross will result in a mixture of the
two genes called a hybrid.