Bio 189 Ch. 8 Genetics

Front 1

quantitative trait loci

Back 1

A set of genes that determines a complex character that exhibits quantitative variation.

Front 2

F2

Back 2

The second filial generation; the immediate progeny of a mating between members of the F1 generation.

Front 3

test cross

Back 3

Mating of a dominant-phenotype individual (who may be either heterozygous or homozygous) with a homozygous-recessive individual.

Front 4

penetrance

Back 4

The proportion of individuals with a particular genotype that show the expected phenotype.

Front 5

phenotype

Back 5

The observable properties of an individual resulting from both genetic and environmental factors.

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wild type

Back 6

Geneticists’ term for standard or reference type. Deviants from this standard, even if the deviants are found in the wild, are usually referred to as mutant.

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allele

Back 7

The alternate form of a genetic character found at a given locus on a chromosome.

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genetic linkage

Back 8

Association between genes on the same chromosome such that they do not show random assortment and seldom recombine; the closer the genes, the lower the frequency of recombination.

Front 9

sex-linked inheritance

Back 9

Inheritance of a gene that is carried on a sex chromosome.

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plasmid

Back 10

A DNA molecule distinct from the chromosome(s); that is, an extrachromosomal element; found in many bacteria. May replicate independently of the chromosome.

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hybrid vigor

Back 11

The superior fitness of heterozygous offspring as compared with that of their dissimilar homozygous parents.

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trait

Back 12

In genetics, a specific form of a character.

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polymorphic

Back 13

Coexistence in a population of two or more distinct traits.

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pedigree

Back 14

The pattern of transmission of a genetic trait within a family.

Front 15

parental (P) generation

Back 15

The individuals that mate in a genetic cross. Their offspring are the first filial (F1) generation.

Front 16

dihybrid cross

Back 16

A mating in which the parents differ with respect to the alleles of two loci of interest.

Front 17

conjugation

Back 17

(1) A process by which DNA is passed from one cell to another through a tube, as in bacteria. (2) A nonreproductive sexual process by which Paramecium and other ciliates exchange genetic material.

Front 18

mutation

Back 18

A change in the genetic material not caused by recombination.

Front 19

homozygous

Back 19

In diploid organisms, having identical alleles of a given gene on both homologous chromosomes.

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codominance

Back 20

A condition in which two alleles at a locus produce different phenotypic effects and both effects appear in heterozygotes.

Front 21

law of independent assortment

Back 21

During meiosis, the random separation of genes carried on nonhomologous chromosomes into gametes so that inheritance of these is random. Mendel's second law.

Front 22

heterozygous

Back 22

In diploid organisms, having different alleles of a given gene on the pair of homologs carrying that gene.

Front 23

Punnett square

Back 23

Method of predicting the results of a genetic cross by arranging the gametes of each parent at the edges of a square.

Front 24

genotype

Back 24

An exact description of the genetic constitution of an individual, either with respect to a single trait or with respect to a larger set of traits.

Front 25

F1

Back 25

The first filial generation; the immediate progeny of a parental (P) mating.

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character

Back 26

In genetics, an observable feature, such as eye color.

Front 27

locus

Back 27

In genetics, a specific location on a chromosome. May be considered synonymous with gene.

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sex pilus

Back 28

A thin connection between two bacteria through which genetic material passes during conjugation.

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carrier

Back 29

In genetics, a person heterozygous for a recessive trait.

Front 30

monohybrid cross

Back 30

A mating in which the parents differ with respect to the alleles of only one locus of interest.

Front 31

recombination frequency

Back 31

The proportion of offspring of a genetic cross that have phenotypes different from the parental phenotypes due to crossing over between linked genes during gamete formation.

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law of segregation

Back 32

The separation of alleles, or of homologous chromosomes, from each other during meiosis so that each of the haploid daughter nuclei produced contains one or the other member of the pair found in the diploid parent cell, but never both. Mendel's first law.

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incomplete dominance

Back 33

Condition in which the heterozygous phenotype is intermediate between the two homozygous phenotypes.

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epistasis

Back 34

Interaction between genes in which the presence of a particular allele of one gene determines whether another gene will be expressed.

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expressivity

Back 35

The degree to which a genotype is expressed in the phenotype; may be affected by the environment.

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recessive

Back 36

In genetics, an allele that does not determine phenotype in the presence of a dominant allele.