Gregor Mendel Modern genetics had its beginnings in an abbey garden, where a monk named Gregor Mendel was first to figure out basic patterns of inheritance. He did so by breeding garden peas in carefully planned experiments.

The work of Gregor Mendel Previous views of Inheritance –Blending –Spermists –Ovists

“Father of Genetics” Mendel’s mathematical patterns were not appreciated until 1900, 16 years after his death 1920s: Meiosis 1950s: Structure of DNA 1960s: Protein Synthesis 1990s: Genome Project

Genetic crosses To hybridize 2 varieties of pea plants, Mendel used an artist’s brush. He transferred pollen from a true breeding white flower to the carpel of a true breeding purple flower.

Pea Traits in Greg’s Garden Flower Position Plant height Pod appearance Pod color Seed Texture Seed Color Sead coat color

Interpreting Mendel’s Data Parent Cross 1st (F1) generation next (F2) generation Round x wrinkled 100% round5,474 round 1,850 wrink. Yellow x green pea 100% yellow 6,022 yell 2,001 green Long x short stem 100% long stem 787 long 277 short

Interpreting Mendel’s Data Parent Cross 1 st (F1) generation next (F2) generation Actual Ratio Probability Ratio Round x wrinkled 100% round5,474 round 1,850 wrink. 2.96:13:1 Yellow x green pea 100% yellow 6,022 yell 2,001 green 3.01:13:1 Long x short stem 100% long stem 787 long 277 short 2.84:13:1

Tracking heritable characteristics Mendel tracked heritable characters for 3 generations. When F 1 hybrids were allowed to self- pollinate a 3:1 ratio of the 2 varieties occurred in the F 2 generation.

Mendel’s law of segregation By carrying out these monohybrid crosses, Mendel determined that the 2 alleles for each character segregate during gamete production.

Mendel’s Observations “dominant” vs “recessive” Before “genes” and “meiosis” was thought of, Mendel theorized that “inheritance factors”… –are in the pollen and ova of peas as alternate forms for different traits. –occur in pairs, (equal contribution from both parents) –separate during gamete formation and pair up again at fertilization

Mendel’s Law of Segregation Each hereditary characteristic is controlled by two factors (alleles) that separate and pass into reproductive cells (gametes).

Mendel’s Law of Independent Assortment Pairs of inheritance factors (alleles) segregate independently of each other when sex cells (gametes) are formed.

Mendelian Inheritance in Humans dominant recessive Tongue Roller (T) Free Earlobes (F) Dimples (D) Widow’s Peak (P) Can’t roll tongue (t) Attached lobes (f) No dimples (d) Straight hairline (w)

Some Vital Vocab. Genetics Genotype vs Phenotype DNA, Chromosome, Gene Alleles (Dominant vs Recessive) Allele Combinations: –Homozygous –Heterozygous