Mendel’s Work – Jigsaw Notes for 09/11/2015-09/14/15 (Friday-Monday)
Mendel’s Work – Page 110
Mendel wanted to learn more about pea plants and why different pea plants had different
characteristics.
Heredity – the passing of physical characteristics from parents to offspring.
Trait – a characteristic that an organism can pass on to its offspring through its genes.
Genetics – the scientific study of heredity.
Mendel’s Experiments – Page 111
Fertilization – the joining of a sperm and an egg.
Pea plants are self-pollinating but Mendel cross-pollinated his plants in his experiment.
Mendel cross-pollinated plants with contrasting traits.
- Example: tall plants and short plants.
Purebred – the offspring of many generations that have the same trait.
- Example: purebred short pea plants always come from short parent plants.
Mendel’s Experiments – Page 112
P generation – the parental generation.
F1 (first filial) generation - the offspring from the cross of the parental generation.
- When Mendel crossed the P generation, tall plants and the short plants, there were
no short plants in the F1 generation.
F2 generation – the offspring from the cross of the F1 generation.
- When Mendel let the F1 generation self-pollinate, there was a mix of tall and short
F2 offspring.
- About ¾ of the offspring plants were tall and ¼ were short.
Dominant and Recessive Alleles – Page 113
Gene – factors that control a trait.
Allele – the different forms of a gene.
- The individual letters used in a Punnett Square.
- Each organism inherits two alleles; one from the female parent and one from the
male parent.
Dominant allele – one whose trait always show up in the organism when the allele is
present.
Recessive allele – a trait that is hidden whenever the dominant allele is present.
Dominant and Recessive Alleles – Page 114
Hybrid – an organism that has two different alleles for a trait, (Tt, Gg, Hh,).
Geneticists use letters to represent alleles.
- Dominant alleles are represented by a capital letter (T, G, H, etc.).
- Recessive alleles are represented by a lowercase letter (t, g, h, etc.).
-Each parent gives an allele to an organism meaning each organism ends up with
two alleles.
-
Homozygous dominant alleles are represented with two capital letters
(TT, GG, HH, etc.).
Homozygous recessive alleles are represented with two lowercase letters
(tt, gg, hh, etc.).
Heterozygous dominant alleles are represented with one capital letter
and one lowercase letter (Th, Gg, Hh, etc.).
Mendel’s Contribution – Page 115
Mendel is now referred to as, “The Father of Genetics.”
Mendel’s discovery confirms that our traits are not simply a blend of our parents’
characteristics but are determined by individual, separate alleles inherited from each
parent