This flashcard set includes the vocabulary words and definitions from Chp 14: Mendel and the Gene Idea (Biology 9E by Campbell et al, 2011). http://robswatski.virb.com

character

an observable heritable feature

trait

any detectable variant in a genetic character

true breeding

referring to plants that produce offspring of the same variety when they self-pollinate

hybridization

the mating, or crossing, of two true-breeding varieties

P generation

the parent individuals from which offspring are derived in studies of inheritance

F1 generation

the first filial, or hybrid, offspring in a series of genetic crosses

F2 generation

offspring resulting from interbreeding of the hybrid F1 generation

allele

any of the alternative versions of a gene that produce distinguishable phenotypic traits

dominant allele

a gene that is fully expressed in the phenotype of a heterozygote

recessive allele

a gene whose phenotypic effect is not observed in a heterozygote

law of segregation

states that the two alleles in a pair separate into different gametes during gamete formation

Punnett square

a diagram used in the study of inheritance to show the predicted results of random fertilization in genetic crosses

homozygous

having two identical alleles for a given gene

heterozygous

having two different alleles for a given gene

phenotype

the physical and physiological traits of an organism, which are determined by its genetic makeup

genotype

the genetic makeup, or set of alleles, of an organism

testcross

breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype

monohybrid

an organism that is heterozygous with respect to a single gene of interest

dihybrid

an organism that is heterozygous with respect to two genes of interest

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

complete dominance

the situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable

incomplete dominance

the situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele

codominance

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

pleiotropy

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

epistasis

a type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited

quantitative character

a heritable feature that varies continuously over a range rather than in an either-or fashion

polygenic inheritance

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

multifactorial

refers to a phenotypic character that is influenced by multiple genes and environmental factors

pedigree

a diagram of a family tree showing the occurrence of heritable characters in parents and offspring over multiple generations

carrier

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

cystic fibrosis

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

Huntington's 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

amniocentesis

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

blending hypothesis

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

stamen

the pollen-producing organ of a flower

carpel

the egg-bearing organ of a flower

cross pollination

fertilization between different plants

locus

a specific place along the length of a chromosome where a given gene is located

monohybrid cross

a cross between individuals that involves one pair of contrasting traits

dihybrid cross

a cross between individuals concentrating on two definable traits

multiplication rule

a rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities

addition rule

the probability that any one of two or more mutually exclusive events will occur is calculated by adding together their individual probabilities

multiple alleles

three or more forms of a gene that code for a single trait; Ex: ABO blood group in humans

achondroplasia

a form of human dwarfism caused by a single dominant allele; the homozygous condition is lethal

albinism

an autosomal recessive hereditary condition characterized by a partial or total lack of melanin pigment, particularly in the eyes, skin, and hair

newborn screening

the analysis of a neonate's blood for metabolic or genetic disorders to prevent mental retardation, disability or death

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