Plant Breeding 2 Quiz I

Allele

Alternative form of a gene at a locus

Breeding

Genetic modification of living organisms

Chomosome

Structural unit in the nucleus that carries genes in a linear order

Cultivar

Cultivated variety of a plant

Dihybrid

Progeny of a cross between parents that differ for the alleles at two loci

Diploid

Individual with two setes of a basic genome (2x)

Dominance

Intrallelic interaction at a heterozygous locus when one allele partially or completely masks the expression of another allele

Enviroment

External conditions that influence expression of genes of an individual

Fertilization

Fusion of an egg and sperm to form a zygote

Gamete

Sex cell produced by the female and male reproductive organs

Gene

Basic unit of inheritance which is a sequence of DNA nucelotides that codes for a functional product of RNA or a polypeptide

Variety

Subdivision of a species for taxanomic classification. Used interchangably with the term cultivar to denote a group of individuals that are distinct genetically from other groups of individuals in the species.

Zygote

Cell formed by the union of female and amel gametes

Strain

A group of similiar and related individuals

Resistant

Characteristic of a plant that is capable oif suppressing or retarding development of a pathogen or other injurious factor

Segregation

Seperation of allelic paris and their distribution to different cells during meiosis

Genetic marker

Allel used to identify a gene, chromosome segment or a chromosome

Genome

Basic set of chromosomes of an organism

Genotype

Genetic makeup of an individual

Genotypic ratio

Proportions of different genotypes ion a population

Germplasm

Total of the genotypes that constitute a species

Haploid

Cell or individual with half (n) of the somatic chromosome number

Heritability

Portion of the phenotypic variation among individuals that is due to genetic differences among them. Broad-sense heritability is estimated from the ratio of the total genetic variance to the phenotypic variance. Narrow-sense heritability is estimated from the ratio of the additive portion of the genetic variance to the phenotypic variance.

Heterosis

Condition in which a hybrid exceeds the performance of it’s parents for one of more characters. Mid-parent heterosis represents performance of the hybrid that exceeds the average performance of the parents per se. High parent heterosis occurs when the hybrid performance exceeds that of the best parents.

Heterozygous

Different alleles are present at a locus on homologous chromosomes in a diploid or polyploid individual such as As in a dipoloid and AAaa in a tetraploid.

Homozygous

Identical alleles are present at a locus on homologous chromosomes in a diploid or polyploid individual such as AA in a diploid or AAAA in a tetraploid.

Hybrid

Progeny of the mating between genetically different parents

Inbred line

Line produced by inbreeding that is homozygous and homogenous

Inbreeding

Mating of individuals that are related by descent

Line

Progeny of an individual plant

Linkage

Condition in which genes located on the same chromosome are inherited together due to their close proximity

Locus

Position occupied by a gene on a chromosome

Mean

Arithmetic average of a series of an observations

Meiosis

Process that occurs in the female and male reproductive organs by which the chromosome number in somatic cells (2n) is reduced by one half (n) in the haploid gametes

Mitosis

Prcoess by which the nucleus of a cell is divided into two genetically identical nuclei

Mutation

Heritable variation in a gene or in chromosome structure

Pedigree

Record of the ancestry of an individual