Gregor Mendel Austrian Monk crossed some pea plants Laws of ____________ There are alternative forms of genes, the units determining heritable characteristics. This is now known as an ____________ An organism inherits one allele from each parent.
Segregation A sperm or egg carries only one allele for each characteristic which pair upon fertilization. When the alleles are different, one is fully expressed and the other is masked, now known as ____________ and recessive genes.
Genes and Dominance Dominance - the ability of one allele to express its ____________ at the expense of an alternate allele; Generally the dominant allele will make a gene product that the recessive can not; therefore the dominant allele will ____________ itself whenever it is present
Lets Practice: What do you get for F1 when your P generation is Homozygous dominant Yellow and green? What if you cross two of the offspring from that cross? What is the F2 generation? What if I said to cross a Tall with a Tall? What are the possible outcomes?
Test Cross When you are not sure of the genotype of the dominant phenotype you do a test cross
More Practice… What if I wanted to know if a flower was likely to be tall/ short and purple/ white? How would I do that?
Dihybrid Cross In any case where the parents are heterozygous for both traits (AaBb x AaBb) you will get a 9:3:3:1 ratio
Independent Assortment This law states that allele pairs separate independently during the formation of ____________ Therefore, traits are transmitted to offspring independently of one another.
Dihybrid Cross A cross (or mating) between two organisms where two genes are studied is called a DIHYBRID cross. The genes are located on separate chromosomes, so the traits themselves are unrelated. BB = black Bb = black bb = white LL = short hair Ll = short hair ll = long hair
Also in rabbits, black eyes are dominant to red eyes. These letters represent the genotypes of the rabbits: GG = gray hair Gg = gray hair gg = white hair BB = black eyes Bb = black eyes bb = red eyes 1. What are the phenotypes (descriptions) of rabbits that have the following genotypes: Ggbb ____________________ ggBB ________________________ ggbb ____________________ GgBb _________________________
A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb The square is set up below. Fill it out and determine the phenotypes and proportions in the offspring. How many out of 16 have grey fur and black eyes? ________ How many out of 16 have grey fur and red eyes? ________ How many out of 16 have white fur and black eyes? ________ How many out of 16 have white fur and red eyes?
Incomplete Dominance When there is no dominant or recessive, the heterozygous condition results in a "blending" of the two traits. Example: Snapdragons can be red, white, or pink (heterozygous) neither allele is dominant, red x white = pink
Codominance Both are expressed in some way, red x white = white/red spots Use all capital letters - Red (RR) x White (WW) = Red and white (RW) The old way still works, though.
Sex linked Traits The genes for these traits are on the _____ chromosome because boys only receive one X chromosome they are more likely to inherit disorders passed to them from their ____________ who would be a carrier. Hemophilia and Colorblindness are sex linked traits, the punnet square below shows how a woman who is a carrier passes the trait to her son, but not her daughters.
Muliple Allele Traits Traits that are controlled by more than two alleles. Blood type in humans is controlled by three alleles: A, B, and O Blood can only be transferred to a body of a person who's immune system will "recognize" the blood. A and B are antigens on the blood that will be recognized. If the antigen is unfamiliar to the body, your body will attack and destroy the transfused blood as if it were a hostile invader (which can cause death).
O is like a blank, it has no antigens. O is called the universal donor because a person can receive a transfusion from O blood without having an immune response AB is the universal acceptor, because a person with AB blood has both the A and B antigens already in the body, A and B blood can be transfused to the person (as well as O) and the body will recognize it and not attack.
Environmentally Influenced Traits Siamese cats have dark ears and feet due to the temperature. Height in humans is influenced by the environment (diet) Traits are influenced by the environment. Pattern baldness affects men because testosterone activates the genes. THE ENVIRONMENT EFFECTS THE EXPRESSION OF GENES!!!!!!