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referring to plants that produce offspring of the same variety when they self-pollinate
law of segregation
states that the two alleles in a pair separate into different gametes during gamete formation
a diagram used in the study of inheritance to show the predicted results of random fertilization in genetic crosses
the physical and physiological traits of an organism, which are determined by its genetic makeup
breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype
law of independent assortment
states that each pair of alleles separates independently of other pairs during gamete formation; applies when genes for two characters are located on different pairs of homologous chromsomes
the situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable
the situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele
the situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways
Tay Sachs disease
a human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain; results in seizures, blindness, and degeneration of motor and mental performance a few months after birth, followed by death within a few years
the ability of a single gene to have multiple effects; Ex: the multiple symptoms associated with certain hereditary diseases such as cystic fibrosis and sickle-cell disease
a type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited
a heritable feature that varies continuously over a range rather than in an either-or fashion
an additive effect of two or more genes on a single phenotypic character; Ex: skin pigmentation in humans
norm of reaction
the range of phenotypes produced by a single genotype, due to environmental influences
refers to a phenotypic character that is influenced by multiple genes and environmental factors
a diagram of a family tree showing the occurrence of heritable characters in parents and offspring over multiple generations
an individual who is heterozygous at a given genetic locus, with one normal allele and one recessive allele, who can pass on the recessive allele to offspring
a human genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated
sickle cell disease
a human genetic disease caused by a recessive allele, resulting in the substitution of a single amino acid in a globin polypeptide that is part of the hemoglobin protein; characterized by deformed red blood cells that can lead to numerous symptoms
a human genetic disease caused by a dominant allele, characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms
a technique of prenatal diagnosis in which amniotic fluid, obtained by aspiration from a needle inserted into the uterus, is analyzed to detect certain genetic and congenital defects in the fetus
chorionic villus sampling
a technique of prenatal diagnosis in which a small sample of the fetal portion of the placenta is removed and analyzed to detect certain genetic and congenital defects in the fetus
the idea that genetic material contributed "mix" together in a way that blue + yellow make green; predicts that over many generations a freely mating population would give rise to a uniform population of individuals; fails to explain how some traits reappear after skipping a generation; disproved by Gregor Mendel
a rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities
the probability that any one of two or more mutually exclusive events will occur is calculated by adding together their individual probabilities
three or more forms of a gene that code for a single trait; Ex: ABO blood group in humans
a form of human dwarfism caused by a single dominant allele; the homozygous condition is lethal
an autosomal recessive hereditary condition characterized by a partial or total lack of melanin pigment, particularly in the eyes, skin, and hair
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