Heredity

Gregor Mendel (1822) Grew up on a farm Studied trees and flowers At 21 joined the monastery The monks taught him science Conducted scientific experiments Went to Vienna to the University to receive training in teaching Did well in classes Could not pass the final tests Returned to the monastery

Mendel’s Peas Mendel noticed patterns in the appearance of plants from generation to generation Some traits appeared and disappeared each generation He noticed the same in other living things also Mendel decided to investigate

He chose pea plants He was familiar with peas They grew quickly There were different varieties They were able to self-pollinate

Self pollinating plants pollinate themselves Able to produce true breeding plants Could also be cross-pollinated Cross pollinating plants need pollen from a second plant Mendel could then study the traits of different characteristic

Mendel’s first experiment Mendel crossed plants with seven different characteristics The first group of offspring are called first- generation plants

Mendel first crossed a purple flowered plant with a white flowered plant In the first generation all the plants had purple flowers????????

Mendel discovered that one trait is always present in the first generation and the other trait disappeared. Mendel called the trait that appeared the dominant trait. Because the other trait seemed to fade into the background, Mendel called it the recessive trait.

Mendel’s second experiment Mendel allowed the first generation plants to self-pollinate The recessive trait reappeared

Mendel discovered that one trait is always present in the first generation and the other trait disappeared. Mendel called the trait that appeared the dominant trait Mendel determined that peas had some traits that were dominate while others were recessive

3 : : 1 3 : : : 1 3 : 1

Traits and Inheritance

What did Mendel discover? Dominant and recessive traits Dominant traits over power the recessive traits Recessive traits stay hidden until the second generation in which they reappear In the second generation the ratio of dominant to recessive traits is 3:1

The organism’s appearance is known as its phenotype The different genes of the appearances is known as the genotype

What did Mendel discover? There are two sets of instructions for each characteristic Scientists now call these instructions genes Each parent gives one set of genes to the offspring The offspring then has two forms of the same gene for every characteristic Each of the different form is known as an allele

T = tall t = short T T T T T T T T T T T T Results Tall = Short = 4 /4 or 100% 0 /4 or 0%

T = tall t = short t T t T T T T t t T t t Results Tall = Short = 3 /4 or 75% 1 /4 or 25%

B = Brown Eyes b = Blue Eyes B B B B B B B B B B B B Results Brown = Blue = 4 /4 or 100% 0 /4 or 0%

B = Brown Eyes b = Blue Eyes b B b B B B B b b B b b Results Brown = Blue = 3 /4 or 75% 1 /4 or 25%

B = Brown Eyes b = Blue Eyes b b b B B b B b b b b b Results Brown = Blue = 2 /4 or 50%

Could you get 75% of the recessive and only 25% of the dominant? No

F = Full Lips f = Thin Lips f F f F F F F f f F f f Results Full = Thin = 3 /4 or 75% 1 /4 or 25% QUIZ

R = Tongue rolling r = Non rolling R r r R R r R r R r R r Results Full = Thin = 4 /4 or 100% 0 /4 or 0% QUIZ

D = Dwarfism d = Normal growth D d d D D d D d D d D d Results Dwarf = Normal = 4 /4 or 100% 0 /4 or 0% QUIZ

U = Unattached earlobe u = Attached earlobe U u u U U u U u U u U u Results Unattached = Attached = 4 /4 or 100% 0 /4 or 0% QUIZ

U = Unattached earlobe u = Attached earlobe u U u U U U U u u U u u Results Unattached = Attached = 3 /4 or 75% 1 /4 or 25% QUIZ

S = Second longer s = Big toe longer s S s s s S s s s S s s Results 2 nd longer = Big toe = 2 /4 or 50% QUIZ

S = Second longer s = Big toe longer s s s s s s s s s s s s Results 2 nd longer = Big toe = 0 /4 or 0% 4 /4 or 100% QUIZ