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Terms and Definitions


genetic make-up of an organism, eg., Tt


physical characteristic of an organism, eg., blonde hair


organism that has two identical alleles for a gene = pure breed=true breeding, eg., TT or tt


organism that has different alleles for a gene, eg., Tt

Incomplete dominance

Heterozygous phenotype is a blend of the two homozygous phenotypes; eg., white and black result in gray


when both alleles show up in the phenotypes, eg, solid color feather parents in speckled chicken feathers


factors that determine a trait passed from one generation to the next


study of heredity; how traits are inherited from geneneration to generation


different forms of a gene


dominant allele hides or masks the recessive; represented by a capital letter


recessive allele is hidden or masked by the dominant

Law of Segregation

For sexually reproducing organisms (like plants and animals) they inherit 2 copies of each gene.


sex cells used for reproduction; guys and girls produce gametes


likelihood that a particular event will take place

Gregor Mendel

the father of genetics


process in which male and female gametes join to produce a new cell


offspring between parents with different traits and characteristics..heterozygous

Pure breed

describes organisms that for many generations have offspring identical to the parent in a characteristic..homozygous


specific characteristic of an individual

Principle of Dominance

Some alleles are dominant and others are recessive

Independent Assortment

genes for different traits segregate independently when gametes are formed

Punnett Square

mathematical diagram that can be used to predict the offspring of a genetic cross

Multiple Allele

more than two alleles are involved in a phenotype

Polygenic Trait

involves the interaction of two or more genes

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