What does Mendel's Law of Segregation state?

What does Mendel's Law of Segregation state?

• A. Alleles segregate during gamete formation; offspring inherit one allele from each parent; typical phenotypic and genotypic ratios for heterozygous crosses are 3:1 and 1:2:1, respectively.
• B. DNA is transcribed into RNA and translated into protein; replication is separate.
• C. Genes on the same chromosome never show recombination.
• D. Nonrandom mating affects allele frequencies.

Answer: (A)

Alleles separate into separate gametes during meiosis, so offspring inherit one allele from each parent. This means a parent that is heterozygous for a gene (Aa) can produce two kinds of gametes, carrying A or a, with equal probability. When fertilization occurs, the gametes unite randomly, giving offspring genotypes in a 1:2:1 ratio (AA:Aa:aa) and, if one allele is dominant, phenotypes in a 3:1 ratio (dominant:recessive). For example, crossing Aa with Aa yields four equally likely offspring: AA, Aa, Aa, and aa, which translates to three showing the dominant trait and one showing the recessive trait. This pattern is the essence of Mendel's Law of Segregation: each parent passes one allele per gene to the offspring, and the two alleles separate during gamete formation. Other statements refer to different genetics concepts: the flow of genetic information (DNA to RNA to protein) is about gene expression, not inheritance; recombination among genes on the same chromosome can occur, so linked genes are not strictly non-recombinant; and nonrandom mating affects allele frequencies in populations, not the segregation of alleles during gamete formation.

Alleles separate into separate gametes during meiosis, so offspring inherit one allele from each parent. This means a parent that is heterozygous for a gene (Aa) can produce two kinds of gametes, carrying A or a, with equal probability. When fertilization occurs, the gametes unite randomly, giving offspring genotypes in a 1:2:1 ratio (AA:Aa:aa) and, if one allele is dominant, phenotypes in a 3:1 ratio (dominant:recessive). For example, crossing Aa with Aa yields four equally likely offspring: AA, Aa, Aa, and aa, which translates to three showing the dominant trait and one showing the recessive trait. This pattern is the essence of Mendel's Law of Segregation: each parent passes one allele per gene to the offspring, and the two alleles separate during gamete formation.

Other statements refer to different genetics concepts: the flow of genetic information (DNA to RNA to protein) is about gene expression, not inheritance; recombination among genes on the same chromosome can occur, so linked genes are not strictly non-recombinant; and nonrandom mating affects allele frequencies in populations, not the segregation of alleles during gamete formation.