Ch. 11 Mendelian Patterns of Inheritance

-This theory stated that offspring would possess traits intermediate between those of different parents. -Red and white flowers blend to produce pink; a later return to red or white progeny was considered instability in genetic material. -The blending theory did not account for variation and could not explain species diversity.

-Mendel was an Austrian Monk -Mendel formulated two fundamental laws of heredity in the early 1860's -He had previously studied science and mathmatics at the University of Vienna. -At time of his research, he was a substitute sceince teacher at local technical high school. -His work remain undiscovered until 1900

-Proposed by Mendel which can account for presenceof differences amoung members of a population generation after generation.

-He chose the garden pea, Pisum Sativum, because peas were easy to cultivate, had a short generation time, and could be cross-pollinated. -From many variaties, Mendel chose 22 true-breeding varieties for his experiments. -True-Breeding-varieties had all offspring likethe parents and like eachother.

-Mendel studied simple traits(ex. seed shape and color, flower color, etc.) -Mendel traced inheritance of individual traits and kept careful records of numbers. -he used his understanding of mathematical principles of probability to interpret results in a statistical study.

-A hybrid is the product of parent organisms that are true-breeding for different forms of one trait. -A Monohybrid cross is between two parent organisms true-breeding for two distinct forms of traits. -Mendel tracked each trait throught two generations.

1. is the parental generation in a breeding experiment 2.is the first-generation offsprings in a breeding experiment 3.is the second-generation offspring in a breeding experiment.

-His results were contrary to those predicted by a blending theory of inheritance -He found that the F1 plants resembled only one of the parents and were all tall. -Characteristic of other parent reappeared in about 1/4 of F2 plants which were small; 3/4 of the offspring resembled the F1 plants and were tall.

-Mendel saw these 3:1 results were possible if: -F1 contained two factors for each trait, one dominant and one recessive; -factors separated when gametes were formed; a gamete carried one copy of each factor -random fusion of all possible gametes occured upon fertilization.

-Each organism contains two factors for each trait; factors segregate in formation of gametes; each gamete contais one factor for each trait. -Mendel's law of segregation is consistant with a particulate theory of inheritance becasemany individual factors are passed on from generation o generation

1. Alternate forms of gene that occur at the same gene locus on homologous chromosomes. 2.is a specific location of a paticular gene on homologous chromosomes.

1. masks or hides expression of a recessive allele; it is represented by an uppercase letter. Ex. T 2. is an allele that exerts its effects only in the homozygous state its expression is masked by a dominant allele; it is represented by a lowercase letter. EX. t

1. genotypes possess two dominant alleles for a trait TT 2. genotypes possess two recessive alleles for a trait. tt 3. genotypes possess one of each allele for a particular trait. -after cross pollination, all individuals of the F1 generation had one of each type of allele Tt

1. refers to the alleles an individual receives at fertilization. (actual genes) 2. refers to the physical appearance of the individual. (outcome of the genes)

-First determine which characteristic is dominant; then code the alleles involved. -Determine genotype and gametes(sperm and egg) for both parents; an individual has two alleles for each trait; each gamete has only one allele for each trait. -Each gamete has a 50% chance of having either allele.