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29 Cards in this Set
- Front
- Back
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selective breeding |
a practice whereby animal or plant breeders choose which individual animals or plants will be allowed to mate based on the traits they hope to produce in the offspring. |
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hybrid |
offspring of parents who differ from each other with regard to certain traits or certain aspects of genetic makeup. heterozygotes. |
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principle of segregation |
genes (alleles) occur in pairs because chromosomes occur in pairs. during gamete formation, the members of each pair of alleles separate, so that each gamete contains on member of each pair. |
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recessive |
describing a trait that isn't expressed in heterozygotes; for it to be expressed and individual must have two copies of it (homozygous). |
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dominant |
in genetics, describing a trait governed by an allele that's expressed in the presence of another allele. it prevents the the expression of recessive alleles in heterozygotes. |
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locus |
the position on a chromosome where a given gene occurs. |
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alleles |
alternate forms of a gene. alleles occur at the same locus on both members of a pair of chromosomes. and are influences by same trait. |
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homozygous |
having the same allele at the same locus on both members of a pair of chromosomes. |
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heterozygous |
having different alleles at the same locus on members of a pair of chromosomes. |
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genotype |
the genetic make up of an individual. |
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phenotypes |
the observable or detectable physical characteristics of an organism. the detectable expressions of genotypes, frequently influenced by environmental factors. |
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principle of independent assortment |
the distribution of one pair of alleles into gametes does not influence the distribution of another pair. the genes controlling different traits are inherited independently of one another. |
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random assortment |
the chance distribution of chromosomes to daughter cells during meiosis. |
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mendelian traits |
characteristics that are influenced by alleles at only one genetic locus. |
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antigens |
large molecules found on the surface of cells. |
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codominance |
the expression of two alleles in heterozygotes. in this situation, neither allele is dominant or recessive, so they both influence the phenotype. |
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polygenic |
referring to traits that are influenced by genes at two or more loci. |
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pigment |
in this context, a molecule that influences the color of skin, hair, and eyes. |
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variation |
in genetics, inherited differences among individuals. |
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allele frequency |
in a population, the percentage of all the alleles at a locus accounted for by one specific allele. |
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population |
within a species, a community of individuals where mates are usually found. |
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gene pool |
all of the genes shared by the reproductive members of a population. |
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microevolution |
small changes occurring within species, such as changes in allele frequencies. |
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macroevolution |
change produced only after many generations, such as the appearance of a new species. |
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gene flow |
exchange of genes between populations. |
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genetic drift |
evolutionary changes, or changes in allele frequencies, that are produced by random factors in small populations. genetic drift is a result of small population size. |
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founder effect |
a type of genetic drift in which allele frequencies are altered in small populations that are taken from, or are remnants of, larger populations. |
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sickle-cell trait |
heterozygous condition in which a person has one Hb^A allele and one Hb^S allele. thus they have some normal hemoglobin. |
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sickle-cell anemia |
a severe inherited hemoglobin disorder in which red blood cells collapse when deprived of oxygen. this allele is caused by a single base substitution in the DNA. |
