Gregor Mendel, the man, the myth, the legend The “Father of Genetics.” Spent 8 years studying pea plants. Developed three important main ideas concerning genetics. 1) Traits are controlled by alleles, which are specific genes. 2) Alleles can be dominant or recessive. 3) During meiosis both alleles for a trait separate onto different cells, so you get one from mom and one from dad.

ALLELES A trait that is hidden is RECESSIVE. HOMOZYGOUS, both alleles are the same, such as TT HETEROZYGOUS, there two different alleles, such as Tt Capital letters, such T, stand for dominant alleles. Lower case letters, such as t, stand for recessive alleles.

PHENOTYPE or GENOTYPE Phenotype = physical appearance. For example, “Tall” Genotype = Genetic makeup of an organism. For example, Tt Dominant alleles cover up recessive alleles. If T is dominant for tall, and t is recessive and means short, and you are TT or Tt, the organism will be Tall. This Photo by Unknown Author is licensed under CC BY-SA

Punnett Squares

Sex-linked Disorders Sex-linked genes are inherited on a sex chromosome (X or Y) XX = female XY = Male. You will get an X from your mom (she doesn’t have a Y) and either an X or Y from Dad (50/50). Color blindness is carried on the X- chromosome, so is a common sex- linked disorder, which men have a lot more often.

Complicated genetics Polygenic inheritance – More than one set of genes controls a trait (such as height). Incomplete Dominance – Both alleles are expressed in the offspring, for example red four o’clock flowers were bred with white four o’clock flowers and the result was pink flowers. Some traits are controlled by multiple alleles, even if you can only get two of those alleles. For example, blood type. You could get an A, B, or O but WILL get only 2 of those, not all three.

Genetic Engineering People have been using selective breeding for thousands of years to improve animals and plants. For example, breeding tall corn with white corn to get tall, white corn, or breeding dogs for traits like calmness or good scent. Genetic engineering is when humans directly alter DNA. GENE THERAPY – A normal allele is placed in a virus. RECOMBINANT DNA – DNA is inserted bacteria to get the bacteria to do something, like improve tomatoes. Genetic engineering makes medicine, improves food longevity, and protects crops from insects.

Do Genes Matter? Genes give your cells directions for your physical traits. Genes play a role in your behavior and personality. However, environment matters a lot in how an organism turns out. Behavior can be affected by social situations. Nutrition and health can greatly affect an organism’s traits.

General Terminology Probability – The chance that an event will take place. Genetics - The study of inheritance Heredity – Passing on traits from one generation to another. Trait – a physical characteristic.