Chapter 11 Vocab Flashcards
an observable heritable feature
character
any detectable variant in a genetic character
trait
referring to plants that produce offspring of the same variety when they self-pollinate
true breeding
the mating, or crossing, of two true-breeding varieties
hybridization
the parent individuals from which offspring are derived in studies of inheritance
P generation
the first filial, or hybrid, offspring in a series of genetic crosses
F1 generation
offspring resulting from interbreeding of the hybrid F1 generation
F2 generation
any of the alternative versions of a gene that produce distinguishable phenotypic traits
allele
a gene that is fully expressed in the phenotype of a heterozygote
dominant allele
a gene whose phenotypic effect is not observed in a heterozygote
recessive allele
states that the two alleles in a pair separate into different gametes during gamete formation
law of segregation
a diagram used in the study of inheritance to show the predicted results of random fertilization in genetic crosses
Punnett square
having two identical alleles for a given gene
homozygous
having two different alleles for a given gene
heterozygous
the physical and physiological traits of an organism, which are determined by its genetic makeup
phenotype
the genetic makeup, or set of alleles, of an organism
genotype
breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype
testcross
an organism that is heterozygous with respect to a single gene of interest
monohybrid
an organism that is heterozygous with respect to two genes of interest
dihybrid
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
law of independent assortment
the situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable
complete dominance
the situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele
incomplete dominance
the situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways
codominance
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
Tay Sachs disease
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
pleiotropy
a type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited
epistasis
a heritable feature that varies continuously over a range rather than in an either-or fashion
quantitative character
an additive effect of two or more genes on a single phenotypic character; Ex: skin pigmentation in humans
polygenic inheritance
the range of phenotypes produced by a single genotype, due to environmental influences
norm of reaction
refers to a phenotypic character that is influenced by multiple genes and environmental factors
multifactorial
a diagram of a family tree showing the occurrence of heritable characters in parents and offspring over multiple generations
pedigree
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
carrier
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
cystic fibrosis
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
sickle cell disease
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
Huntington’s disease
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
amniocentesis
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
chorionic villus sampling
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
blending hypothesis
the pollen-producing organ of a flower
stamen
the egg-bearing organ of a flower
carpel
fertilization between different plants
cross pollination
a specific place along the length of a chromosome where a given gene is located
locus
a cross between individuals that involves one pair of contrasting traits
monohybrid cross
a cross between individuals concentrating on two definable traits
dihybrid cross
a rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities
multiplication rule
the probability that any one of two or more mutually exclusive events will occur is calculated by adding together their individual probabilities
addition rule
three or more forms of a gene that code for a single trait; Ex: ABO blood group in humans
multiple alleles
a form of human dwarfism caused by a single dominant allele; the homozygous condition is lethal
achondroplasia
an autosomal recessive hereditary condition characterized by a partial or total lack of melanin pigment, particularly in the eyes, skin, and hair
albinism
the analysis of a neonate’s blood for metabolic or genetic disorders to prevent mental retardation, disability or death
newborn screening
