Inheriting Traits
Parental cross makes F1 Generation
Mendel's work is still very important to this day. His concept of genetics was simple. Mendel was interested in traits that he noticed in pea plants (Flower color, seed color, seed shape, pod shape, color, and height), he determined that there must be a way to explain why plants have certain traits and others do not. In his observations, Mendel noticed that there were some plants that had dominant characteristics while others had traits that were not as common (recessive). He came to a point where he concluded that there must be a unit factor (gene) responsible for the traits that plants possess. He noted that these unit factors are made up of two parts for each traits (alleles). Mendel assigned alleles in a single- factor cross or test to determine the offspring of plants using one trait he used the following experiment:
Parent generation: P generation
TT x tt= F1 generation (4 plants all Tt, Tall)
F1 generation:
Tt x Tt= F2 generation(4 plants TT, Tt, Tt, tt) 3 tall 1 dwarf
These were the results of some of the first experiments with pea plants. In order to more clearly explain the inheritance seen above, a few terms need to be understood. When determining the make up of an organism we need to use the term genotype (the genetic make up of the organism "Tt" or "TT"); There is a difference in saying if the plant is heterozygously tall (Tt) or homozygously tall (TT), the difference cannot be told in just looking at the organism but needs to be known when determining what its future offspring may end up looking like. The way in which scientists name how an organisms traits are perceived is the word phenotype.
Parent generation: P generation
TT x tt= F1 generation (4 plants all Tt, Tall)
F1 generation:
Tt x Tt= F2 generation(4 plants TT, Tt, Tt, tt) 3 tall 1 dwarf
These were the results of some of the first experiments with pea plants. In order to more clearly explain the inheritance seen above, a few terms need to be understood. When determining the make up of an organism we need to use the term genotype (the genetic make up of the organism "Tt" or "TT"); There is a difference in saying if the plant is heterozygously tall (Tt) or homozygously tall (TT), the difference cannot be told in just looking at the organism but needs to be known when determining what its future offspring may end up looking like. The way in which scientists name how an organisms traits are perceived is the word phenotype.
The phenotype of this F2 generation shows that 75% of the plants are green and that 25% are yellow but this does not mean that they all have the same genetic make up, in fact 25% are YY, 50% are Yy and 25% are yy. This is the difference between genotype and phenotype for a particular trait.
Create your own single factor cross using the trait Round "RR" and wrinkled "rr" in the P generation. Use Punnett squares to determine genotype and phenotype of the F2 generation to follow. Answer the following questions after yu have completed the cross:
Is a single factor cross bound to work the same for every trait?
What is the genotypic ratio of round and wrinkled plant seeds?
What is the phenotype?
Read the following about Independent Assortment and Dihybrid (two factor) cross and complete the final stage of the mission:
Complete the cross to the F2 generation from the following parents:
(Tall and Green) TTYY x (dwarf and yellow) ttyy
write the phenotypic and genotypic ratio of the F2 generation. (There will be 16 plants)
Use the picture of a dihybrid cross or two factor cross for assistance.
Create your own single factor cross using the trait Round "RR" and wrinkled "rr" in the P generation. Use Punnett squares to determine genotype and phenotype of the F2 generation to follow. Answer the following questions after yu have completed the cross:
Is a single factor cross bound to work the same for every trait?
What is the genotypic ratio of round and wrinkled plant seeds?
What is the phenotype?
Read the following about Independent Assortment and Dihybrid (two factor) cross and complete the final stage of the mission:
Complete the cross to the F2 generation from the following parents:
(Tall and Green) TTYY x (dwarf and yellow) ttyy
write the phenotypic and genotypic ratio of the F2 generation. (There will be 16 plants)
Use the picture of a dihybrid cross or two factor cross for assistance.