| A | B |
|---|
| heredity | the transmission of charecters from parents to offspring. |
| traits | characteristics |
| pollination | occurs when pollen grains produced in the male reproductive parts of a flower are transferred to the female reproductive part of a flower. |
| anthers | male reproductive part of a flower. |
| stigma | female reproductive part of a flower. |
| self-pollination | occurs when pollen is transferred from the anthers of a flower to the stigma of either the same flower or a flower of the same plant. |
| cross-pollination | involves flowers of two seperate plants. |
| pure | plants that always produce offspring with one trait. |
| strain | plants that are pure for a specific trait. |
| P1 generation | a parental generation. |
| F1 generation | the offspring of the P1 generation, or the first filia generation. |
| F2 generation | second filial generation. |
| dominant factor | an allele that masks the presence of another allele for the same characteristic. |
| recessive factor | an allele that is masked by the presence of another allele for the same characteristic. |
| the law of segregation | a pair of factors is segregated or seperated during the formation of gametes. |
| the law of independent assortment | factors for different characteristics are distributed to gametes independently. |
| Molecular genetics | the study of the sturcture and function of chromosomes and genes |
| allele | each of several alternative forms of a gene. |
| genotype | the genetic makeup of an organism. |
| phenotype | the appearance of an organism as a result of its genotype. |
| homozygous | when both alleles of a pair are alike |
| heterozygous | when the two alleles in the pair are different. |
| Probablility | the likelihood that a specific event will occur. |
| monohybrid | a cross between individual that involves one pair of contrasting traits |
| punnett square | a diagram to aid in the prediction of the probability that certain traits will be inherited by offspring. |
| genotypic ratio | the ratio of genotypes that appear in offspring. |
| phenotypic ratio | the ratio of the offsprings' phenotypes. |
| testcross | an individual of unknown genotypeis grossed with a homozygous recessive individual. |
| complete dominance | heterozygous plants and dominant homozygous plants are indistinguishable in phenotype. Pp flower and a PP flower are both purple. |
| incomplete dominance | the F1 offspring will have a phenotype in between that of their parents. ex...Red plants x White plants = Pink plants. |
| Codominance | when both alleles for a gene are expressed in a heterozygous offspring. ex...when a pure white horse crosses w/ a pure red horse, the offspring has red and white hairs: Roan. |
| dihybrid cross | a cross between individuals that involves two pairs of contrasting traits. ex...seed color and texture. |
| XX | female |
| XY | male |
| X-linked genes | genes found on the X chromosome. |
| Y-linked genes | genes found on the Y chromosome. |
| sex linkage | the presence of a gene on a sex chromosome. |
| linkage group | the genes located on one chromosome. |
| Chromosome map | a diagram that shows the linear sequence of genes on a chromosome. |
| one map unit | the distance between two genes that re separated by crossing over one percent of the time. |
| Germ-cell mutations | occur in an organism's gametes or germ cells. The don't affect organism itself but they may be passed to offspring. |
| Somatic mutations | take place in an oranism's body cells and can affect the organism. |
| Lethal mutations | cause death, often before birth. |
| deletion | the loss of a piece of chromosome due to chomosomal breakage. |
| inversion | a chromosome mutation which a chromosomal segment breaks off and then reattaches upside down on the same chromosome. |
| translocation | a chromosome piece breaks off and reattaches to another, nonhomologous chromosome. |
| Nondisjunction | the failure of a chromosome to seperate from its homogue during meiosis. |
| point mutation | the substitution, addition, or removal of a single nucleotide. |
| substitutions | one nucleotide in a codon is replaced with a different nucleotide, resulting in a new codon. |
| sickle cell anemia | genetic disorder caused by a point mutation, and results in a defective form of the protein hemoglobin. |
| frame shift mutation | occur anytime the numver of nucleotides inserted or deleted is not a multiple of three. |
| pedigree | a family record that shows how a trait is inherited over several generations. |
| patterns of inheritence | repeating phenotypes which are predictible from one generation to the next. |
| genetic disorders | diseases or debiltating conditions that have a genetic basis. |
| Single-allele traits | controlled by a single allele of a gene. |
| Huntington's disease (HD) | caused by a dominant allele located on an autosome and is therefore said to show and autosomal-dominant pattern of inheritance. |
| genetic marker | a short section of DNA that is nearby. |
| Multiple-allele traits | controlled by three or more alleles of the same gene that code for a single trait. |
| polygenic trait | a trait that is controlled by two or more genes. |
| Colorblindness | recessive X-linked disorder in which an individual can usually not distinguish between certain colors. |
| Hemophilia | a recessive X-linked diseasse that occurs almost exclusively in males. Impairs the ability of the blood to clot. |
| Duchenne Muscular Distrophy | a form a md that weakens and progressively destroys muscle tissue. |
| sex-infulenced traits | the expression of certain human traits which in influenced by the presence of male or female sex hormones. |
| monsomy | a zygote with 45 chromosomes that has only one copy of a particualr chromosome. |
| trisomy | a zygote with 47 chromosomes has three copies of a particular chromosome. |
| Down syndrome | genetic disease caused by a trisomy on chromosal pair 2.1 |
| genetic screening | an examination of a person's genetic makeup. |
| genetic counseling | a form of medical guidence that informs them about problems that could ffect their offspring. |
| amniocentesis | test of the amniotic fluid which surrounds a baby in utero. |
| chorionic villi sampling | testing of the tissue which grows between the mother's uterus and the placenta. |
| phenylketonuria (PKU) | a genetic disorder in which the body cannot metabulize the amino acid phenylalanine which causes sever brain damage. |
