Biology
Genetic Traits Exercise:
Introduction:
The pioneer of modern day genetics was an Austrian Monk named Gregor Mendel, who established the basic laws of heredity from his studies with pea plants in the late 1800s. Mendel’s fundamental genetic principles may be applied to a variety of traits from many different organisms.
Each genetic trait, such as flower color, is regulated by a pair of genes called alleles. These alleles are found at particular places on the chromosomes called loci. During meiosis, each pair of alleles splits up or segregates so that only one allele from each pair is contained within a gamete (egg or sperm.) This is Mendel’s Law of Segregation. In sexual reproduction egg and sperm from parents unite to form a new individual or zygote. Thus, each parent contributes one allele for each genetic locus. Mendel’s Law of Independent Assortment states that during meiosis, each pair of alleles is assorted randomly and inherited independently of the others. Note that this principle holds true only for genes that are located on different chromosomes.
If the two alleles for a trait are different (heterozygous) rather than alike (homozygous), the dominant allele will be expressed over the other (recessive) one. Scientists use an upper case letter to symbolize a dominant allele and a lower case of the same letter to symbolize the recessive allele. For example, in garden peas a purple flower is dominant over a white flower. Thus, A=purple allele, and a=white allele. In some cases, neither allele is dominant and a blending of the trait results. Other traits are sex-limited and are only expressed in one sex. Observable characteristics of an organism, e.g., blue eyes or freckles, are referred to as the phenotype while the genes actually regulating a particular phenotype are known as the genotype of the organism.
Although many human traits are regulated by complex genetic principles, Mendel’s Laws can be used to illustrate the inheritance of
Introduction:
The pioneer of modern day genetics was an Austrian Monk named Gregor Mendel, who established the basic laws of heredity from his studies with pea plants in the late 1800s. Mendel’s fundamental genetic principles may be applied to a variety of traits from many different organisms.
Each genetic trait, such as flower color, is regulated by a pair of genes called alleles. These alleles are found at particular places on the chromosomes called loci. During meiosis, each pair of alleles splits up or segregates so that only one allele from each pair is contained within a gamete (egg or sperm.) This is Mendel’s Law of Segregation. In sexual reproduction egg and sperm from parents unite to form a new individual or zygote. Thus, each parent contributes one allele for each genetic locus. Mendel’s Law of Independent Assortment states that during meiosis, each pair of alleles is assorted randomly and inherited independently of the others. Note that this principle holds true only for genes that are located on different chromosomes.
If the two alleles for a trait are different (heterozygous) rather than alike (homozygous), the dominant allele will be expressed over the other (recessive) one. Scientists use an upper case letter to symbolize a dominant allele and a lower case of the same letter to symbolize the recessive allele. For example, in garden peas a purple flower is dominant over a white flower. Thus, A=purple allele, and a=white allele. In some cases, neither allele is dominant and a blending of the trait results. Other traits are sex-limited and are only expressed in one sex. Observable characteristics of an organism, e.g., blue eyes or freckles, are referred to as the phenotype while the genes actually regulating a particular phenotype are known as the genotype of the organism.
Although many human traits are regulated by complex genetic principles, Mendel’s Laws can be used to illustrate the inheritance of