Chapter 11.1

1. Chapter 11.1 Mendel, Pea Plants, and Inheritance Patterns AP Biology Fall 2010

2. Blending Inheritance Vs. Inheritance Patterns • Late 19th century, natural selection suggested that a population could evolve if members show variation in heritable • Variations that improved survival chances would be more common in each generation • In time, population would change or evolve

3. Blending Inheritance Vs. Inheritance Patterns • Theory of Natural Selection did not fit with prevailing view of inheritance • Blending • Blending would produce uniform populations; such populations could not evolve

4. Blending Inheritance Vs. Inheritance Patterns • Many observations did not fit blending • White horse and black horse did not produce gray ones

5. Blending Inheritance Vs. Inheritance Patterns • Gregor Mendel used experiments in plant breeding and knowledge of mathematics to form his hypotheses

6. Mendel’s Experimental Approach • Mendel used the garden peas for his experiments • This plant can fertilize itself; true breeding varieties were available to Mendel • Peas can be cross fertilized by human manipulation of pollen • Self fertilizing: flowers produce both male and female gametes • True breeding: successive generations will be like parents in one or more traits • White flowered parent plants give rise to white flowered offspring

7. Mendel’s Experimental Approach • Mendel hypothesized that clearly observable differences might help him track the trait and identify inheritance patterns and heredity

8. Terms Used in Modern Genetics • Genes: units of information about specific traits, each located at a particular locus on a chromosome • Homologous Chromosome: diploid cells have 2 genes (a gene pair) for each trait- each on a homologous chromosome • Mutation: alters a gene’s molecular structure • Alleles: are various molecular forms of a gene for the same trait • Page 171, figure 11.4

9. Terms Used in Modern Genetics • True Breeding Lineage: occurs when offspring inherit identical alleles, generation after generation • Hybrid Offspring: what non-identical alleles produce • Homozygous: when both alleles are the same • Heterozygous: when the alleles differ • When heterozygous one allele is dominant (A) and the other allele is recessive (a)

10. Terms Used in Modern Genetics

11. Terms Used in Modern Genetics • Homozygous dominant: AA • Homozygous recessive: aa • Heterozygous:Aa • Genotype: is the particular alleles an individual carries • Phenotype: is how the genes are expressed physically (what you observe) • P: true breeding parental generation • F1: first generation offspring • F2: second generation offspring of self fertilized or intercrossed F1 individuals

12. Review • Jeopardy