Campbell Essential Biology Ch 9

Front 1

Heredity

Back 1

The transmission of traits from one generation to the next.

Front 2

Genetics

Back 2

The scientific study of heredity (inheritance)

Front 3

Character

Back 3

A heritable feature that caries among individuals within a population, such as flower color in pea plants

Front 4

Trait

Back 4

A variant of a character found within a population, such as purple flowers in pea plants.

Front 5

True-breeding

Back 5

Referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents. The organisms are homozygous for the characteristics under consideration.

Front 6

Hybrids

Back 6

The offspring of parents of two different species or of two different varieties of one species; the offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes.

Front 7

Cross

Back 7

The cross-fertilization of two different varieties of an organism or of two different species; also called hybridization.

Front 8

P generation

Back 8

The parent individuals from which offspring are derived in studies of inheritance. P stands for parental.

Front 9

F1 generation

Back 9

The offspring of two parental (P generation) individuals. Stands for first filial.

Front 10

F2 generation

Back 10

The offspring of the F1 generation. Stands for second filial.

Front 11

Monohybrid Cross

Back 11

A mating of individuals differing at one genetic locus.

Front 12

Alleles

Back 12

An alternative version of a gene.

Front 13

Homozygous

Back 13

Having two identical alleles for a given gene.

Front 14

Heterozygous

Back 14

Having two different alleles for a given gene.

Front 15

Dominant Allele

Back 15

In a heterozygotes, the allele that determines the phenotype with respect to a particular gene.

Front 16

Recessive Allele

Back 16

In heterozygotes, the allele that has no noticeable effect on the phenotype.

Front 17

Law of Segregation

Back 17

A general rule of inheritance, first proposed by Gregor Mendel, that states that when gametes form during meiosis, each pair of alleles for a particular character segregate (separate) independently of each other pair.

Front 18

Punnett Square

Back 18

A diagram used in the study of inheritance to show the results of random fertilization.

Front 19

Phenotype

Back 19

The expressed traits of an organism.

Front 20

Genotype

Back 20

The genetic makeup of an organism.

Front 21

Locus (Plural Locus)

Back 21

The particular site where a gene is found on a chromosome. Homologous chromosomes have corresponding gene loci.

Front 22

Dihybrid Cross

Back 22

An mating of individuals differing at two genetic loci.

Front 23

Law of Independent Assortment

Back 23

A general rule of inheritance, first proposed by Gregor Mendel, that states that when gametes form during meiosis, each pair of alleles for a particular character segregate (separate) independently of each other pair.

Front 24

Testcross

Back 24

The mating between an individual of unknown genotype for a particular character and an individual that is homozygous recessive for that same character.

Front 25

Rule of Multiplication

Back 25

A rule stating that the probability of a compound event is the product of the separate probabilities of the independent events.

Front 26

Wild-type Traits

Back 26

The trait most commonly found in nature.

Front 27

Pedigree

Back 27

A family tree representing the occurrence of heritable traits in parents and offspring across a number of generations.

Front 28

Carrier

Back 28

An individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder.

Front 29

Cystic Fibrosis

Back 29

A genetic disease that occurs in people with two copies of a certain recessive allele; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated.

Front 30

Achondroplasia

Back 30

A form of human dwarfism caused by a single dominant allele. The homozygous condition is lethal.

Front 31

Huntington's Disease

Back 31

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10-20 years after the onset of symptoms.

Front 32

Incomplete Dominance

Back 32

A type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA and aa).

Front 33

Hypercholesterolemia

Back 33

An inherited human disease characterized by an excessively high level of cholesterol in the blood.

Front 34

ABO Blood Groups

Back 34

Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The phenotypes, also called blood types, are A, B, AB, and O.

Front 35

Codominance

Back 35

The expression of two different alleles of a gene in a heterozygote.

Front 36

Pleitropy

Back 36

The control of more than one phenotypic character by a single gene.

Front 37

Sickle-cell Disease

Back 37

A genetic disorder in which the red blood cells have abnormal hemoglobin molecule and take on an abnormal shape.

Front 38

Polygenic Inheritance

Back 38

The additive effect of two or more genes on a single phenotypic characterisitc.

Front 39

Chromosome Theory of Inheritance

Back 39

A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

Front 40

Linked Genes

Back 40

Genes located close enough together on a chromosome that they are usually inherited together.

Front 41

Linkage Map

Back 41

A map of a chromosome showing the relative positions of genes.

Front 42

Recombination Frequency

Back 42

With respect to two given genes, the number of recombinant progeny from a mating divided by the total number of progeny. Recombinant progeny carry combinations of alleles different from that seen in either of the parents as a result of independent assortment of chromosomes and crossing over.

Front 43

Sex-linked Gene

Back 43

A gene located on a sex chromosome.

Front 44

Red-green Colorblindness

Back 44

A category of common sex-linked human disorders involving several genes on the X chromosome and characterized by a malfunction of light-sensitive cells in the eyes; affects mostly males but also homozygous females.

Front 45

Hemophilia

Back 45

A human genetic disease caused by a sex-linked recessive allele and characterized by excessive bleeding following injury.