| A | B |
|---|
| allele | part of a gene that codes for a physical trait: one of a number of different forms of a gene that contributes to a particular genotypic or phenotypic trait |
| chromosome | a thread-like structure made of molecules within the nucleus that contains genetic information that is passed from one generation to the next |
| codominance | the phenotypes produced by both alleles are completely expressed together (black fur parent + white fur parent = offspring with spots of each color) |
| crossing-over | process in which homologous chromosomes exchange portions of their chromatids during meiosis, thereby shuffling genes between homologous chromosomes |
| diploid | a cell that contains 2 sets of homologous chromosomes (2n) - 46 in humans |
| gamete | sex cell, such as a sperm or an egg |
| gene | a sequence of DNA that codes for/determines a specific trait |
| genotype | genetic make-up of an organism in terms of alleles present |
| haploid | cell that contains 1 set of chromosomes: 1n - (23) in humans |
| heterozygous | having 2 different alleles for a particular gene |
| homologous | pairs of chromosomes in which 1 set (23) of chromosomes comes from the mother and 1 set (23) of chromosomes comes from the father |
| homozygous | having 2 identical pairs of alleles for a particular gene |
| incomplete dominance | one allele is not completely dominant over the other, and phenotype results in a mixture of the 2 alleles, where the heterozygous genotype results in a new phenotype (such as red + white = pink) |
| meiosis | the process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Only happens in sex cells, not somatic cells. |
| phenotype | the physical characteristics of an organism that are expressed as traits |
| punnett square | a diagram that can be used to predict the genotypic and phenotypic outcomes for one ore more traits, of the combinations of a genetic cross between 2 parents |
| polygenic trait | a trait which involves more than one gene |
| Gregor Mendel | an Austrian monk who through his experiments on pea plants in the early 19th century, discovered patterns in genetic inheritance |
| F1 generation | offspring from two true-breeding parents (PP + ww = all Pw) |
| genetic probability | the expected outcome of genotype and phenotype, depending on the chance of choices of traits in offspring occurring |
| calculating genetic probability | if there is a 50-50% chance, multiply 1/2 to the exponent of the number of outcomes (ex: the odds of having 5 girls in a row is shown as 1/2 to the 5th power (answer: odds are 1/32) |
| F2 generation | the offspring of F1 generation parents (usually resulting in a 3:1 phenotypic outcome and a 1:2:1 genotypic outcome) |
| normal allele | form of a gene that codes for the normal sequence of amino acids making the correct protein |
| Mendel's 3 Laws (Mendelian Genetics) | Law of Heredity; Law of Independent assortment; Law of Dominance |
| Law of Segregation | alleles separate into gametes randomly |
| Law of Independent Assortment | Genes for different traits mix randomly in gametes |
| Law of Dominance | Some alleles are dominant over other alleles |
| number of daughter cells produced in mitosis | 2 |
| number of daughter cells produced after meiosis | 4 |
| zygote | a fertilized egg |
| tetrad | formed during the first phase of meiosis - the two homologous chromosomes will align next to each other (each is made up of two sister chromatids it will look like a group of four) |
| hybrid | offspring from a true-breeding cross - example: purple (PP) x white pea (pp) flowering plants = Pp |
| multiple allele trait | a trait contolled by many alleles in one gene (base pair changes) |
