BIO.B.2 Genetics
Topic Summary for Mendelian Inheritance Patterns:
The delivery of characteristics from parents to offspring is heredity. The scientific study of heredity is genetics. Gregor Mendel founded modern genetics with his experiments on a convenient model system, pea plants:
Fertilization is the process in which reproductive cells (egg from the female and sperm from the male) join to produce a new cell.
A trait is a specific characteristic, such as (in peas) seed color or plant height.
Mendel prevented self-pollination in the peas. He controlled fertilization so he could study how traits passed from one generation to the next.
He created hybrids, which are crosses between true-breeding parents (the P generation) with different traits.
• These hybrids were the F1 (first filial) generation.
• They each showed the characteristic of only one parent.
Mendel found that traits are controlled by factors that pass from parent to offspring. Those factors are genes. The different forms of a gene are alleles.
Mendel’s principle of dominance states that some alleles are dominant and others are recessive. The recessive allele is exhibited only when the dominant allele is not present.
Mendel allowed members of the F1 generation to self-pollinate. The trait controlled by the recessive allele appeared in the next generation (F2) in about one-fourth of the offspring—even when it did not appear in the F1 generation.
Separation of alleles is segregation.
When gametes (sex cells) form, alleles segregate so that each gamete carries only one allele for each gene.
The F2 generation gets a new combination of alleles: one from each parent.
Topic Summary for Mendelian Inheritance Patterns:
The delivery of characteristics from parents to offspring is heredity. The scientific study of heredity is genetics. Gregor Mendel founded modern genetics with his experiments on a convenient model system, pea plants:
Fertilization is the process in which reproductive cells (egg from the female and sperm from the male) join to produce a new cell.
A trait is a specific characteristic, such as (in peas) seed color or plant height.
Mendel prevented self-pollination in the peas. He controlled fertilization so he could study how traits passed from one generation to the next.
He created hybrids, which are crosses between true-breeding parents (the P generation) with different traits.
• These hybrids were the F1 (first filial) generation.
• They each showed the characteristic of only one parent.
Mendel found that traits are controlled by factors that pass from parent to offspring. Those factors are genes. The different forms of a gene are alleles.
Mendel’s principle of dominance states that some alleles are dominant and others are recessive. The recessive allele is exhibited only when the dominant allele is not present.
Mendel allowed members of the F1 generation to self-pollinate. The trait controlled by the recessive allele appeared in the next generation (F2) in about one-fourth of the offspring—even when it did not appear in the F1 generation.
Separation of alleles is segregation.
When gametes (sex cells) form, alleles segregate so that each gamete carries only one allele for each gene.
The F2 generation gets a new combination of alleles: one from each parent.