Post on 06-Jan-2018
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Genetics: The Science of Heredity
Mendel’s WorkChapter 3Section 1
Heredity
• The set of chromosomes that an offspring receives from its parents
• Genetics– The study of heredity
Gregor Mendel
• European Monk– 1800’s
• Bred pea plants– “Father of Genetics”
Pollination
• Self-Pollination– Pollen fertilizes egg
cells of the same flower
• Cross-Pollination– Pollen from one flower
fertilizes egg cells of another flower
Traits
• A characteristic that distinguishes one individual from another
• Mendel’s Seven– Seed shape– Seed color– Seed coat color– Pod shape– Pod color– Flower position– Plant height
Hybrids
• An offspring of parents with different characteristics
• P-generation– parents
• F1-generation– The first generation of
offspring
• F2-generation– The second generation
of offspring
Genes
• The unit that determines traits
• Examples…– Tall or short– Red or blonde hair– Freckles or no freckles
Alleles
• The different forms of a gene
• Eye alleles…– Blue– Brown– Green
Dominant vs. Recessive
• Dominant– The allele that is
expressed• “T” = tall
– CAPITAL LETTER!!!
• Recessive– The allele that is not
expressed• “t” = short
– Lower case letter
Homozygous vs. Heterozygous
• Homozygous– TT
• Both genes are for the tall gene
– tt• Both genes are for the
short gene
• Heterozygous– Tt
• The 2 alleles are different