Heredity is the passing of traits to offspring from its parents or ancestor. This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve. The study of heredity in biology is called genetics, which includes the field of epigenetics. In humans, eye color is an example of an inherited characteristic: an individual might inherit the brown-eye trait from one of the parents.[1] Inherited traits are controlled by genes and the complete set of genes within an organisms genome is called its genotype.[2] The complete set of observable traits of the structure and behavior of an organism is called its phenotype. These traits arise from the interaction of its genotype with the environment.[3] As a result, many aspects of an organisms phenotype are not inherited. For example, suntanned skin comes from the interaction between a persons phenotype and sunlight;[4] thus, suntans are not passed on to peoples children. However, some people tan more easily than others, due to differences in their genotype:[5] a striking example is people with the inherited trait of albinism, who do not tan at all and are very sensitive to sunburn.[6] Heritable traits are known to be passed from one generation to the next via DNA, a molecule that encodes genetic information.[2] DNA is a long polymer that incorporates four types of bases, which are interchangeable. The sequence of bases along a particular DNA molecule specifies the genetic information: this is comparable to a sequence of letters spelling out a passage of text.[7] Before a cell divides through mitosis, the DNA is copied, so that each of the resulting two cells will inherit the DNA sequence. A portion of a DNA molecule that specifies a single functional unit is called a gene; different genes have different sequences of bases. Within cells, the long strands of DNA form condensed structures called chromosomes. SOC. SCI ass.
Posted on: Sun, 06 Jul 2014 23:24:04 +0000
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