2.  A Punnett square shows the possible outcomes of a cross, but it can also be used to calculate the probability of each outcome.  Probability is the likelihood that a specific event will occur.  Probability can be expressed in words, as a decimal, as a percentage, or as a fraction.  Probability formulas can be used to predict the probabilities that specific alleles will be passed on to offspring.  The possible results of a heterozygous cross are similar to those of flipping two coins at once.

3.  A pedigree is a diagram that shows how a trait is inherited over several generations of a family.  Pedigrees can be used to help a family understand a genetic disorder.  A genetic disorder is a disease or disorder that can be inherited.  A pedigree can help answer questions about three aspects of inheritance: sex linkage, dominance, and heterozygosity.

4.  Human generations are longer than 20 years  Must rely on family histories and medical records  Pedigree  diagram that follows the inheritance of a single gene through several generations in a family   = Male, O = Female   connects parents   connects parents to children  children are placed from left to right in birth order  Homozygous trait shaded in  Heterozygous trait 1/2 shaded

7.  Are there exceptions to the simple Mendelian pattern of inheritance?  How do heredity and the environment interact to influence phenotype?  How do linked genes affect chromosome assortment and crossover during meiosis?

8.  Most patterns of inheritance are more complex than those that Mendel identified.  The Mendelian inheritance pattern is rare in nature; other patterns include:  polygenic inheritance  incomplete dominance  multiple alleles  codominance. Polygenic character  A character that is influenced or affected by more than one gene  Examples: Eye color, height, and skin color  Most characters are polygenic.

10. Multiple alleles  Genes that have three or more possible alleles  Example: control the ABO blood groups (blood types) in humans.  Incomplete Dominance  A condition where an offspring has a phenotype that is intermediate between the two traits of its parents  Example: Snapdragons: red and white with the intermediate trait being pink  R- gene for red flowers, W- gene for white flowers:  RR- red, WW- white, RW- pink

12. Example: Snapdragons RR = Red WW = White All RW = Pink

13. Codominance  a condition in which both alleles for the same gene are fully expressed.  Example: The genetics of human blood groups  Another example- Chicken feathers  B- gene for black feathers, W- gene for white feathers:  BB- black, WW- white, BW- “erminette” Black and White!

14.  Phenotype can be affected by conditions in the environment, such as nutrients and temperature.  In humans, many characters that are partly determined by heredity, such as height, are also affected by the environment.  Many aspects of human personality and behavior are strongly affected by the environment, but genes also play an important role.

15.  The Mendelian inheritance pattern is rare in nature; other patterns include polygenic inheritance, incomplete dominance, multiple alleles, and codominance.  Phenotype can be affected by conditions in the environment, such as nutrients and temperature.  During meiosis, genes that are close together on the same chromosome are less likely to be separated than genes that are far apart.