| A | B | 
| phenotype | what the trait looks like | 
| genotype | the genetic code for a trait | 
| trait | factors or characteristics of an organism | 
| heredity | the passing of traits from parents to their offspring | 
| genetics | the study of heredity | 
| self pollination | pollen is transferred to the female part of the same flower | 
| examples of inherited traits | examples:  eye color, hair color, tall or short, tongue roll, cleft chin | 
| cross pollination | pollen is tranferred to the female part of another flower | 
| pollen | contains sperm of flowers | 
| dominant | the trait that will be expressed in a hybrid | 
| recessive | the trait that will be hidden in a hybrid | 
| hybrid | an organism with different genes for the same trait, one from each parent | 
| purebred | an organism which has the same genes for a trait, one from each parent | 
| homozygous | has the same genes or alleles for a trait | 
| heterozygous | having different genes or alleles for a trait | 
| Gregor Mendel | austrian monk - father of modern genetics | 
| pea plants | the kind of plant Mendel used in his study of heredity | 
| genes | a section of DNA which controls a trait | 
| alleles | another name for a gene | 
| DNA | deoxyribose nucleic acid | 
| one strand of DNA | what makes up a chromosome | 
| chromosome | found in the nucleus of every cells, contains instructions for everything the cell does | 
| 23 pairs | the number of chromosomes humans have | 
| the 23rd pair | called the sex chromosomes because determine whether you are male or female | 
| XY | letters that stand the male chromosomes | 
| XX | letters that stand for the female chromosomes | 
| replicates | make an exact copy of itself - chromosomes do this | 
| meiosis | the type of cell division that results in eggs and sperm | 
| mitosis | the kind of cell division which all cells do to grow and repair | 
| both parents | all body cells contain genetic instructions from ------ ------- | 
| the egg | contains half the number of chromosomes | 
| sperm | contain one half the number of chromosomes | 
| fertilized egg | contains the full number of chromosomes | 
| adenine | the A base of DNA | 
| guanine | the G base of DNA | 
| cytosine | the C base of DNA | 
| thymine | the T base of DNA | 
| Punnett Square | the chart used to determine possible genotypes of offspring | 
| codominance | 2 forms of the same gene are expressed at the same time WITHOUT BLENDING, ex.some cattle have white hair and red hair | 
| incomplete dominance | blending of traits instead of dominance, ex. in flowers a red gene and a white gene result in a pink flower | 
| sex-linked traits | traits that are caused by genes on the X chromosome, but not on the Y | 
| mutation | a change in the gene pattern | 
| selective breeding | deliberately breeding certain individual organisms to get certain traits, ex:breeding cows to be resistant to anthrax | 
| gene mapping | finding the position of specific genes on a chromosome | 
| polyploidy | extra sets of chromosomes in an organism | 
| sex chromosome | the 23rd pair of chromosome in humans | 
| carrier | the individual which carries the recessive gene for a trait | 
| PKU | an inherited disease which causes brain damage and mental retardation, all babies are tested for this at birth | 
| sickle-cell anemia | inherited disease which causes red blood cells to take on a sickle shape | 
| multiple alleles | a single trait is caused by the action of 2 of several genes, ex. human eye color could be green, blue, brown, hazel, gray |