Mendelian Genetics
Mendel created two laws in regards to genetic crossing. The first one, the law of segregation, states that two alleles separate into different gametes. In other words, one of the alleles is sent into one gamete, and the other into another gamete. Therefore, when fertilization occurs, each new organism is given an allele for a trait from each parent. His second law, the law of independent assortment, is the idea that one trait does not alter another.
Heterozygous vs. Homozygous
Genes are made up of two alleles, one from each parent. For example if the allele received from mom is a dominant for brown eyes, B, is paired with a recessive allele from dad with blue eyes, the offspring is said to be heterozygous, Its two alleles are Bb, one dominant and one recessive. However if the offspring was given the same allele from both parents, either both dominant brown eye alleles or both recessive alleles for blue eyes, the offspring is said to have homozygous genes. The alleles will either be BB or bb.
If the dominant trait is present anywhere, it will be the one that shows. If only the recessive genes are received, the recessive trait will show. Codominance results in both traits showing. Incomplete dominance is when there is a blend in both traits and that is what shows.
Genes are made up of two alleles, one from each parent. For example if the allele received from mom is a dominant for brown eyes, B, is paired with a recessive allele from dad with blue eyes, the offspring is said to be heterozygous, Its two alleles are Bb, one dominant and one recessive. However if the offspring was given the same allele from both parents, either both dominant brown eye alleles or both recessive alleles for blue eyes, the offspring is said to have homozygous genes. The alleles will either be BB or bb.
If the dominant trait is present anywhere, it will be the one that shows. If only the recessive genes are received, the recessive trait will show. Codominance results in both traits showing. Incomplete dominance is when there is a blend in both traits and that is what shows.
Punnett Squares
Punnett Squares are the probability of inheritance based on the parent's genotype. Both of the parents genes are put together in a square to calculate the different genetic probabilities of the offsrping. For example, down below, both parents are heterozygous. Within each square, you drop in the allele and bring one in from the side to form possible alleles. The dominant will always come first. Below, the parents have a 25% chance of making a homozygous dominant, 25% of it being homozygous recessive, and there is a 50% chance that the offspring, or F1 generation will be heterozygous.
Punnett Squares are the probability of inheritance based on the parent's genotype. Both of the parents genes are put together in a square to calculate the different genetic probabilities of the offsrping. For example, down below, both parents are heterozygous. Within each square, you drop in the allele and bring one in from the side to form possible alleles. The dominant will always come first. Below, the parents have a 25% chance of making a homozygous dominant, 25% of it being homozygous recessive, and there is a 50% chance that the offspring, or F1 generation will be heterozygous.
Pedigrees
Pedigrees is the recording of ancestry. It studies the inheritance of genes in humans. In the example below, the first generation has an affected male and a non affected female. They pass on their genes to their kids who either do not carry the gene or they do. The cyle continues and the possible genotypes for each following offspring can be determined using punnett squares.
Pedigrees is the recording of ancestry. It studies the inheritance of genes in humans. In the example below, the first generation has an affected male and a non affected female. They pass on their genes to their kids who either do not carry the gene or they do. The cyle continues and the possible genotypes for each following offspring can be determined using punnett squares.