Glossary Terms: Q - T

Terms

  1. Recombination

  2. Replication

  3. RNA (Ribonucleic Acid)

  4. Sequencing

  5. Sex Chromosomes

  6. Sexual Selection

  7. Single Nucleotide Polymorphism

  8. Trait

Definitions

  1. Recombination

    The process by which each parent contributes half of an offspring’s DNA, creating an entirely new genetic identity. This process mixes genetic signals. Thus, nonrecombining DNA, which is passed intact through the generations, is most important in population genetics.

  2. Replication

    The process by which two DNA strands separate, with each helping to duplicate a new strand. During reproduction, the DNA double helix unwinds and duplicates itself to pass on genetic information to the next generation. Because bases always form established pairs (AT and CG), the sequence of bases on each strand will attract a corresponding match of new bases. Only occasional errors occur—about one for every billion base-pair replications.

  3. RNA (Ribonucleic Acid)

    Transfers the genetic “blueprint” that is stored in DNA during protein production. RNA has a single-stranded linear structure and a slightly different chemical composition from DNA.

  4. Sequencing

    Determines the order of nucleotides for any particular DNA segment or gene. The order of a DNA string’s base pairs determines which proteins are produced, and thus the function of a particular cell.

  5. Sex Chromosomes

    The sex chromosomes determine your sex. Each human cell has 23 pairs of chromosomes: 22 autosomal pairs and one pair of sex chromosomes, of which there are two kinds—X and Y. While all other chromosomes are found in matching pairs, it is the mismatch of the Y chromosome with the X chromosome that determines male gender—men have both a Y and X, while women have two Xs. The Y chromosome is passed virtually intact from fathers to their sons, and for this reason, its genetic markers make it a useful molecule for tracing paternal ancestry. However, because only males have the Y chromosome, we’re unable to report a female participant’s direct paternal lineage.

  6. Sexual Selection

    A special form of natural selection based on an organism’s ability to mate. Some animals possess characteristics that are more attractive to potential mates, such as the distinctive plumage of some male birds. Individuals with such characteristics mate at higher rates than those without, ensuring more next generation offspring will inherit the desirable trait. As generations procreate, the desirable trait becomes increasingly common, further boosting the sexual disadvantage for individuals who lack the desired trait. The effect can be particularly dramatic when one individual controls mating with a large number of potential partners.

  7. Single Nucleotide Polymorphism

    Small, infrequent changes that help to create an individual’s own unique DNA pattern. When a single nucleotide (A, T, G, or C) is altered during DNA replication due to a tiny “spelling mistake,” the genome sequence is altered.

  8. Trait

    Traits are physical characteristics, like eye color or nose shape, determined by genes that are passed from parent to child.