Mendel and Heredity Mendel and Heredity When a magician makes a coin disappear, you know the coin has not really vanished. You simply cannot see where it is. Maybe it is up a sleeve or in a pocket. When organisms reproduce, some traits seem to disappear too. For centuries, no one could explain why. Then a careful, observant scientist showed that behind this phenomenon were inherited traits units, or genes. This scientist was Gregor Mendel.

Mendel and Heredity Gregor Mendel laid the groundwork for genetics. Genetics: the study of heredity …. how traits gets passed from parent to offspring. Traits are inherited characteristics such as eye color, leaf color, and tail length. Mendel experimented on pea plants because they reproduce quickly and he could control how they mate.

Mendel and Heredity

Mendel crossed tall and short pea plants. He referred to the offspring of this cross as hybrids. Hybrids: offsprings of parents that have different forms of a trait. For example; tall and short Mendel’s first experiments are called monohybrid crosses because only 1 trait was crossed. P1 Generation are the original parents. Hence P, stands for parent. The offsprings of the parents are known as F1 generation. The F stands for filial. Filial means son or daughter. When you cross two F1 plants with each other, their offsprings are called the F2 generation.

P1 Parents F1 You F2 Your children

T_________ t___________ The different forms of a gene are called alleles. One allele is inherited from the mom and the other from the dad. There are dominant and recessive traits. Dominant traits are recognized by a Capital letter and recessive traits are a lower case. Dominant alleles will always cover up a recessive allele. B ________ b _________ T_________ t___________

BB ____________________ Genotype is the letter (gene) combination. For ex; Bb Phenotype is the way the organism looks. For ex; tall and skinny. BB ____________________ Widow’s Peak ___________ Tt ____________________

BB________ tt_________ Bb________ Ww_______ bb_________ WW_______ Homozygous has 2 of the same alleles. Either 2 capital letters or 2 lower case letters. Ex; TT , tt Heterozygous has 2 alleles that are different. Contains a capital and lower case letter. BB________ tt_________ Bb________ Ww_______ bb_________ WW_______ Tt__________ gg________

Try this  BB: ________________ Identify each genotype as homozygous dominant, homozygous recessive, or heterozygous. Identify each genotype as a hybrid or purebred.

A monohybrid cross between 2 heterozygous tall pea plants. Tall is the dominant trait and short is the recessive. Phenotypes:________________________________

In garden peas, round seed coats (R) is dominant to wrinkled seed coats (r). What will the result be of a cross between a homozygous dominant male and a recessive female?

Tall is dominant to short. Cross 2 heterozygous tall individuals.