Q:

What is the difference between dominant and recessive alleles?

A:

Quick Answer

Dominant alleles are always expressed in the organism, while recessive traits tend to be expressed only when the dominant allele is not present. The relationship between dominant and recessive genes is described by the Law of Segregation. As related by About.com, Gregor Mendel observed nine different traits among his pea plants and found that certain traits, such as pod color, bred true only when two recessive alleles were present.

Know More
What is the difference between dominant and recessive alleles?
Credit: Thomas Barwick Taxi Getty Images

Full Answer

Sexually reproducing organisms carry two copies of each gene in their DNA. When these two copies are the same, or "homozygous," their effect is to produce whatever trait the genes are identified with. When different versions of the gene are paired, however, what usually happens is that one gene is expressed at the expense of the other. The expressed trait is then described as dominant.

By carefully isolating nine separate traits in his pea plants, Mendel was able to show that each trait--such as plant height and pod color--bred true in self-fertilized plants. When the plants were cross-fertilized, however, their traits did not blend; tall and short plants didn't produce medium-height plants, for example. Instead, according to Genome.gov, three out of four offspring were tall. In this case, tall was a dominant allele.

Learn More

Related Questions

  • Q:

    What is a PhD in chemical engineering?

    A:

    A Ph.D. in chemical engineering is a high-level academic achievement that awards the title of "doctor of philosophy in chemical engineering." Doctoral degrees are awarded when a student has completed an undergraduate degree, a master's degree and the requirements for earning a Ph.D.

    Full Answer >
  • Q:

    What is the function of the Golgi body?

    A:

    The Golgi apparatus collects simple chemicals in the cell and assembles them into large, complex structures such as proteins. It also plays a role in the process of simple chemical secretion by forming closed vesicles around the substance to be transported. These vesicles then pinch off from the Golgi apparatus and drift to the cell's plasma membrane where the transported substance is released from the cell.

    Full Answer >
  • Q:

    What gene is responsible for a blue-eyed cat?

    A:

    There are at least three different genes that can produce blue eyes in cats: the dominant white gene, the recessive white gene associated with color points and the white-spotting gene. All of these genes affect the production of melanin, regardless of whether it is in the skin, fur or eyes.

    Full Answer >
  • Q:

    Does baldness come from your mother's father?

    A:

    Some scientists have concluded that male pattern baldness is handed down via a faulty gene through the male's maternal line. In other words, a man can get an idea of how his hair loss is likely to proceed from the appearance of men in his mother's family. The suspicious gene is in the X chromosome, which men inherit from their mothers.

    Full Answer >

Explore