General: Understand the concepts underlying Mendelian Genetics. Specific: 1. Identify the factors that influence individuality. 2. Describe the experiment of Mendel and explain their importance to the science of heredity. 3. Solve monohybrid crosses.

 Background about Gregor Mendel’s life.  Mendel and his experiment.  Characteristics of the garden pea.  Dominant and Recessive Traits  Monohybrid Crosses

Responsible for the Laws governing Inheritance of Traits

 Austrian Monk  Studied at the Agustinian Monastary of St. Thomas in Brno  Studied the inheritance of traits in pea plants  Developed the laws of inheritance  Mendel's work was not recognized until the turn of the 20th century

 Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants  He found that the plants' offspring retained traits of the parents  Called the “Father of Genetics"

 Many earlier investigations was done that produced hybrid peas by crossing different varieties.  Large number of true-breeding varieties was available.

 Pea plants are small and easy to grow and they have relatively short generation.  Both the male and female sexual organs are enclosed within the pea flower.

 Pollen contains sperm  Produced by the stamen  Ovary contains eggs  Found inside the flower Pollen carries sperm to the eggs for fertilization Self-fertilization can occur in the same flower Cross-fertilization can occur between flowers

C. True-breeding A. Cross-breeding B. Hybrid-breeding

 Allowed pea plants of a given variety to produce offspring by self-fertilization for several years. (True-breeding)  Performed crosses between varieties exhibiting alternative forms of characters. (cross-breeding)  Permitted the hybrid offspring to produce by self fertilization for several generations.

True-breeding Cross-breeding Hybrid-breeding

2 B 2 2,,

 Flower color --- Purple (W) or white ( w )  Seed Color ---- Yellow (G) or Green ( g )  Seed shape --- Round (W) or Wrinkled (w)  Pod Color --- Green (Y) or Yellow (y)  Pod Shape --- Inflated(C) or Constricted ( c )  Flower position---Axial (T) or Terminal (t)  Plant Height --- Tall (D) or Dwarf (d)

 Dominant - stronger genes are expressed in the hybrid; represented by a capital letter (R)  Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r)

 Homozygous - gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure  Homozygous - gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure  Heterozygous - gene combination of one dominant & one recessive allele (e.g. Rr); also called hybrid

 PHENOTYPE is any observable characteristic or trait of an organism: such as its morphology and development.  GENOTYPE isthe genetic makeup of a cell, an organism, or an individual. Represented by letters (WW, YY, Yy, Dd)

 An alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome.

True-breeding Cross-breeding Hybrid-breeding

 Used to determine if an individual exhibiting a dominant trait is homozygous or heterozygous for that trait.dominant trait homozygousheterozygous

True-breeding Cross-breeding Hybrid-breeding

 Cross between two individuals having single traits of particular interest.  Monohybrid inheritance is the inheritance of a single characteristic. Example: Plant Seed Color (Yellow x Green) Flower Position (Axial x Terminal)

 Parental P 1 Generation = the parental generation in a breeding experiment.  F 1 generation = the first-generation offspring in a breeding experiment. (1st filial generation)  From breeding individuals from the P 1 generation  F 2 generation = the second-generation offspring in a breeding experiment. (2nd filial generation)  From breeding individuals from the F 1 generation

 a diagram that is used to predict an outcome of a particular cross or breeding experiment.  Reginald C. Punnett Reginald C. Punnett

 Trait: Flower Color W – Purplew – White W – Purplew – White  Cross: Purple Flower x White Flower  WW x ww w w WW WwWw WwWwWwWw WwWw F1 Genotype:Ww F1 Genotype: Ww F1 PhenotypePurple F1 Phenotype: Purple Ratio:All alike Ratio: All alike

36  Trait: Flower Color Ww – Purple Ww – Purple Ww – Purple Ww – Purple  Cross: Purple Flower x Purple Flower  W w x W w W w w W WW ww WwWw WwWw F2 Genotype: _____ F2 Phenotype F2 Phenotype: _____ Genotype Ratio: ___ Phenotype Ratio Phenotype Ratio: ___

 UNIT FACTORS IN PAIRS  Genetic characters are controlled “unit factors” that exist in pairs.  DOMINANCE/RECESSIVENESS  When two unlike unit factors is responsible for a single trait, one unit factor is dominant and the other is unexpressed.  SEGREGATION  During gamete formation, the paired unit factors separate or segregate. GENES

 In summer squash, white fruit color (Y) is dominant over yellow fruit color (y). If a squash plant homozygous for white is crossed with a plant homozygous for yellow, what will the phenotypic and genotypic ratios be for: a. the F 1 generation? b. the F 2 generation?

 LAW of DOMINANCE  LAW Of SEGREGATION  LAW IF INDEPENDENT ASSORTMENT

 Law of Dominance- States that when pure-breeding plants having contrasting characters are crossed, all the offspring will show only one of the characters. That which appears is the dominant character; that which does not appear is the recessive character.

 Principle of Segregation- For any particular trait, the pair of alleles of each parent separate and only one allele passes from each parent on to an offspring.

It describes how genes are transmitted from parent to offspring.

 Principle of Independent Assortment- Different pairs of alleles are passed to offspring independently of each other. The result is that new combinations of genes present in neither parent are possible. For example, a pea plant's inheritance of the ability to produce purple flowers instead of white ones does not make it more likely that it will also inherit the ability to produce yellow pea seeds in contrast to green ones.