Chapter 5 - Vocabulary Flashcards
Additive Allele
an allele that has a partial influence on a phenotype.
Allele
a specific form of a gene.
Autosomal Inheritance
inheritance of alleles located on autosomal (non-sex) chromosomes.
Carrier Testing
a genetic test that determines whether an individual is heterozygous for a given gene that results in a genetic disorder.
Codominance
a situation where both alleles are expressed fully to produce offspring with a third phenotype.
Complete Dominance
a situation where an allele will determine the phenotype, regardless of the presence of another allele.
Continuous Variation
when the product of one gene is affected by the product of another gene, the gene products may be additive, or one product may negate another product.
Cross
the successful mating of two organisms from distinct genetic lines.
Dihybrid Cross
a cross that involves two genes, each consisting of heterozygous alleles.
Discontinuous Variation
when the expression of the products of one gene has no bearing on the expression of the products of a second gene.
Dominant Allele
the allele that, if present, is always expressed.
F1 Generation
the offspring of a P-generation cross
F2 Generation
offspring of an F1-generation cross.
Genetic Screening
tests used to identify the presence of a defective allele that leads to a genetic disorder.
Genotype
the genetic makeup of an individual/
Heterozygous
describes an individual that carries two different alleles for a given characteristic.
Homozygous
describes an individual that carries two of the same alleles for a given characteristic.
Hybrid
the offspring of two different true-breeding plants.
Incomplete Dominance
a situation where neither allele dominates the other and both have an influence on the individual; results in partial expression of both traits.
Law of Independent Assortment
if genes are located on separate chromosomes, they will be inherited independently of one another.
Law of Segregation
a scientific law stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only one copy of each gene to their gametes because the genes separate during gamete formation.
Monohybrid
the offspring of two different true-breeding plants that differ in only one characteristic.
Monohybrid Cross
a cross designed to study the inheritance of only one trait.
Mutation
a change in the genetic code of an allele; the change may have a positive effect, a negative effect, or no effect.
Pedigree
a diagram of an individual’s ancestors used in human genetics to analyze Mendelian inheritance of a certain trait; also used for selective breeding of plants and animals.
P Generation
the parent plants used in a cross.
Punnett Square
a diagram that summarizes every possible combination of each allele from each parent; a tool for determining the probability of a single offspring having a particular genotype.
Phenotype
an individual’s outward appearance with respect to a specific characteristic.
Phenylketonuria (PKU)
an autosomal, recessive, inherited genetic disorder that results in the accumulation of phenylalanine in the tissues and blood.
Probability
the likelihood that an outcome will occur if it is a matter of chance.
Product Law
the probability of two independent random events both occurring is the product of the individual probabilities of the events.
Recessive Allele
the allele that is expressed only if it is not in the presence of the dominant allele, that is, if the individual is homozygous for the recessive allele.
Sex-Linked
describes an allele that is found on one of the sex chromosomes, X or Y, and when passed on to offspring is expressed.
Test Cross
a cross used to determine the genotype of an individual expressing a dominant trait.
Trait
a particular version of a characteristic that is inherited, such as hair colour or blood type.
True-Breeding Organism
an organism that produces offspring that are genetically identical for one or more traits when self-pollinated or when crossed with another true-breeding organism for the same traits.
X-Linked
phenotypic expression of an allele that is found on the X chromosome.
Y-Linked
phenotypic expression of an allele that is found on the Y chromosome.
