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25 terms

Biology- Chapter 8- KEY TERMS

Alphabetical Order. Definitions will be exactly what you see. -Justin
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Allele
an alternative form of a gene
Codominance
condition in which both alleles for a gene are expressed when present
Dominant
genetic trait that is expressed when its allele is homozygous or heterozygous
F1 generation
the first offspring from a cross of two varieties in the parental generation
F2 generation
the offspring from the crosses among individuals of the F1 generation
Genetics
the study of heredity
Genotype
the genetic makeup of an organism as indicated by its set of alleles
Heredity
transmission of genetic traits from parent to offspring
Heterozygous
refers to an individual with two different alleles for a trait
Homozygous
refers to an individual with two identical alleles for a trait
Incomplete dominance
a condition in which a trait in an individual is intermediate between the phenotype of its two parents
Law of independent assortment
second law of heredity stating that pairs of genes separate independently of one another in meiosis
Law of segregation
the first law of heredity stating that pairs of alleles for a trait separate when gametes are formed
Monohybrid cross
cross involving one pair of contrasting traits
Multiple alleles
the existence of more than two alleles for a genetic trait
P generation (parental generation)
the first two individuals that mate in a genetic cross
Pedigree
family history that shows how a trait is inherited over several generations
Phenotype
observable characteristics of an organism
Polygenic trait
characteristic of an organism that is influenced by several genes
Probability
the likelihood that a specific event will occur
Punnett square
diagram used by biologist to predict the probable outcome of a genetic cross
Recessive
a genetic trait that is not expressed when the contrasting form of the trait is present
Sex-linked trait
a trait that is determined by a gene found on the X chromosome
Test cross
a genetic cross of an individual whose phenotype is dominant but whose genotype is unknown, with a homozygous recessive individual
True-breeding
displaying only one form of a particular trait in offspring