Introduction To Genetics- Chapter 11. I. The work of Gregor Mendel. A. Gregor Mendel was born in 1822 and after becoming a priest; Mendel was a math teacher for 14 years and a monastery. Mendel was also in charge of the monastery garden. . 1. Mendel carried out his work with garden peas.
A. Gregor Mendel was born in 1822 and after becoming a priest; Mendel was a math teacher for 14 years and a monastery. Mendel was also in charge of the monastery garden.
3. True breeding plants are plants that were allowed to self-pollinate and the offspring would be exactly like the parent.
1. The different forms of a gene is called and an alleles.
2. The principal of dominance states that some alleles are dominant and others are recessive.
At John Burke High School they tested dominant and recessive traits in our school population. We tested pinky finger traits, whereby, the bent finger is dominant and the straight finger is recessive.
1. Each trait has two genes, one from the mother and one from the father.
2. Traits can be either dominant or recessive.
3. A dominant trait only needs one gene in order to be expressed.
6. Segregation is the separation of alleles during gamete formation.
A. Genetics and Probability
1. The likelihood that a particular event will occur is called probability.
2. The principals of probability can be used to predict the outcome of genetic crosses.
1. The gene combination that might result from a genetic cross can be determined by drawing a diagram known as a Punnett square.
2. Punnett squares can be used to predict and compare the genetic variations that will result from a cross.
4. Alleles can be homozygous – having the same traits.
5. Alleles can be heterozygous- having different traits.
7. Genetic make up is the genotype.
A. Independent assortment
1. Genes segregate independently.
3. Independent assortment helps account for the many genetic variations observed in plants, animals and other organisms.
1. Genes are passed from parent to offspring.
2. Some forms of a gene may be dominant and others recessive.
4. The alleles for different genes usually segregate independently of one another.
1. Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.
2. Cases in which one allele is not completely dominant over another are called incomplete dominance.
Example: Feather colors
a. This means that more than two possible alleles exist in a population. Example: colors of rabbits see page 273.
a. Example: eye color has many different genes.
1. Mendel’s principals do not only apply to plants.
A. Chromosome number
1. Every individual has two sets of chromosomes. One from the mother one from the father. When the chromosomes pair up for the same trait they are called homologous chromosomes.
3. Gametes (egg /sperm) have only one chromosome and are said to be haploid/ n.
1. Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.
2. Meiosis I- ****The homologous chromosomes line up BUT then they CROSS OVER, exchanging genetic information.
Go to Internet: www.SciLinks.org code cbn-4114 to view meiosis.
A. Gene linkage
1. Thomas Hunt Morgan research on fruit flies led him to the principal of linkage.
2. Morgan discovered that many genes appeared “linked” together.
4. Mendel DID miss gene linkage.
6. Crossing over creates genetic diversity.