An Austrian scientist =research in a Czechoslovakian monastery.
Established the basis of modern genetic science.
Objective = understand how physical traits are passed from a parent to its offspring.
Dominance vs Recessiveness
Principle of Segregation.
Principle Independent Assortment
Monohybrid and Dihybrid cross
Important Terms Alleles – Genetic factors that controls a trait, Dominant = ability to mask the expression of a recessive allele (Capital) Recessive = masked by a dominant allele Homozygous - 2 identical alleles (TT, tt) Heterozygous - 2 different alleles (Tt) Genotype - genes of an organism = alleles received during fertilization. Phenotype = the physical appearance of a trait in an organism . Eg blue eyes, yellow flower
Genotype = genes present in an organism (usually abbreviated as two letters
TT - Homozygous Dominant (PURE)
tt -Homozygous Recessive (PURE)
Tt - Heterozygous
Alternative forms of the same gene.
Gene for hair texture (curly? Straight?)
One form of the hair texture gene codes for curly hair. A different code for of the same gene makes hair straight.
= So the gene for hair texture exists as two alleles --- one curly code, and one straight code.
tall stem x short stem = (F1) ALL TALL
yellow seeds x green seeds = (F1) ALL YELLOW
round seeds x wrinkled seeds = (F1)ALL ROUND
Conclusion of Exp 1
phenotypes of the offspring resembled only one of the parent plants.
alleles compete randomly for expression in the offspring depending on Dom/Rec status
F1 = T x tt = All Tt . the tall factor seems to DOMINATE the short factor".
F2 = The trait not shown in the F1 reappeared in the F2 in about 25% of the offspring
Different offspring of the same parents have different sets of hereditary information
Mendels Law The Law of Segregation
pair of alleles of each parent separate and only one allele passes from each parent on to an offspring.
Which allele in a parent's pair of alleles is inherited is a matter of chance.
segregation of alleles occurs during the process of sex cell formation = MEIOSIS
Mendel's Law of Independent Assortment
Alleles for different traits are distributed to sex cells (& offspring) independently of one another.
Conseq ; new combinations of genes present in neither parent are possible.
two different traits:
(1) seed texture (round or wrinkled) &
(2) pod color (green or yellow).
The different traits do not influence the inheritance of each other. They are inherited INDEPENDENTLY
Yellow round, green wrinkled vs Yellow wrinkled, green round
where "G" = dominant allele for yellow pods "g" = recessive allele for green pods
“ W" = dominant allele for round seeds “w" = recessive allele for wrinkled seeds .