Part 2: Heredity and Mendelian Genetics
The Genetics of Inheritance Traits. Ex. Earlobes, Dimples, Curved Fingers, Rolling Tongue Inheritance The mechanism that between generations.
Genetics The branch of biology that deals with the Farmers knew about before these principles were scientifically proven. People have been domesticated for millennia.
The of how these processes occurred were unknown.
A few theories arose The Greek philosophers:, 460-377 B.C.E., suggested that the body produced and that these seeds to give rise to a., 384-322 B.C.E., proposed that mixed upon conception.
In the 1500 s, English physician, theorized that a process called was how inheritance occurred. A process based upon the development of the, and affected by the mother. Dutch Scientist and Microscopist,, used a microscope in the mid to late 1600 s to examine the and other animals.
Leeuwenhoek later proposed that the male sperm actually contained which would later be in the mother s uterus. Preformation Theory
Sperm and Egg at Conception
Charles Darwin suggested, in the mid 1800 s that children had characteristics that were, but he was unable to explain the. The answer to came from Darwin s contemporary
Mendel s Contributions The Father of Modern Genetics Gregor Mendel 1822-1884
The Inheritance of One Trait Gregor Mendel, an Austrian monk, studied the using the common as an experimental model. Prior to Mendel s work at the Monastery of St. Thomas in Brunn, he attended the University of. While at the University, his studies included training that would later prove to be invaluable.
Why did Mendel choose the pea plant (Pisum sativum) as an experimental model for his study?
The position of the of the plant are entirely ; this allowed Mendel control over.
The plants exhibited between generations. Each trait had only.
How did Mendel set up his experiment? The first thing he did was for each of the traits he wished to study. This process ensured he was working with plants that. i.e. the plants produced when any of the same were bred together.
Mendel prepared a for each of the he studied. Each of these were easily identified in the of the offspring generation. The seven traits were:
Before we jump in: - Solving genetics problems involves an (the measure of how likely an event is). Complete the following:
Mathematically To determine probabiliy: = # of ways an event can occur Total # of Outcomes
A Monohybrid Cross Mendel s first experiment involved the. Mendel called this the. From this cross, the offspring were referred to as the These were called because they resulted from the.
This type of cross is called because only, was involved.
A monohybrid cross
The results of the experiment Mendel s first experiment showed that a. That is, all of the. This led Mendel to conclude that the trait for over the.
Dominant & Recessive Traits Dominant Trait a characteristic that is. Only must be present for the to be expressed. Recessive Trait a trait that is that code for the are present. In Mendel s experiments, he found that one.
Mendel s Principle of Dominance When, the offspring will only express the.
Back to Exp. 1 Monohybrid Cross Punnett Square Tall Plant T T Short Plant t t
Mendel s next experiment involved the crossing of. He allowed the to undergo.
Exp. 2 Monohybrid Cross with F1 Offspring Punnett Square Tall Plant T t Tall Plant T t
This produced a, that Mendel called the. of plants in the F2 generation were This ratio of has become known as the.
Mendel drew four conclusions from his experiments: Each parent in the F1 generation begins with. Individual The factors are and each factor to each.
Each offspring from each parent. If the by the offspring, it will be ; even if the. The recessive factor will.
The Law of Segregation Inherited traits are. These factors when the are formed. One factor from in each gamete.
F1 Hybrid Cross (Showing Segregation)
What are factors? We now know that Mendel s factors. A can occur in When are present, a and the is not. Each of these will pass on to the where they may or may not.
The arrangement of alleles. Alleles can be identified by using a. i.e. The usually determines the letters of the for the code. For example the would be, with both for a dominant trait. The code for a.
If the code read, it should be understood that this individual would be. The arrangement in which both alleles are represented by the To clarify, one must indicate the organism as being either
The arrangement in which both alleles are represented by The following terms will help you read about and describe heredity:
A tall-stem pea plant could have two. A short-stem pea plant can have only since the allele for
Phenotype refers to the. Since a pea plant can be tall or short, there are. The tall phenotype may have
Sample Problem 1 Consider a cross between a pea plant that is heterozygous for round seeds and a pea plant that has wrinkled seeds. Determine the genotypes of the possible offspring.
Sample Problem 2 A plant that is homozygous for purple flowers is crossed with a plant that has white flowers. If the purple condition is dominant over the white condition, what are the genotypes and phenotypes of the F1 generation?
Sample Problem 3 Determine the genotypes of the parents if the following offspring are produced.