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HUMAN DEVELOPMENT Human development is a concept that has been researched and explored by experts for centuries throughout human history. Through the time researchers have found out that genetics have a big influence on human development.

Human development starts when the male reproductive cell, or sperm, penetrates the protective outer membrane of the female reproductive cell, or ovum. The sperm and ovum each contain chromosomes that act as a blueprint for human life. The genes contained in these chromosomes are made up of a chemical structure known as DNA that contains a genetic code which is used to control functions, behavior and development of an organism. DNA is also used as a long term storage device to store the genetic instructions. These instructions must be correct so the DNA can make an exact copy of itself. DNA is bundled into 46 chromosomes, 23 from both male and female germ cells. This ensures that when the two cells meet, the resulting new organism has the correct 46 chromosomes.

Genetics instructions are passed from both parents and this influence the traits that they will acquired. The names of these traits inherited are called genotype and phenotype. A genotype refers to all of the genes that a person has inherited. The actual express of these traits is the person's phenotype. The phenotype can include physical traits, such as height and color or the eyes, as well as nonphysical traits.

Whether or not a gene is expressed depends on two different things: the interaction of the gene with other genes and the continual interaction between the genotype and the environment. Genetic

Interactions can sometimes contain conflicting information, and in most cases, one gene will win the battle for dominance. For example, if a child has one tall parent and one short parent, the child may end up splitting the difference by being of average height. Eye color is another example of dominant-recessive genes.

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