Heredity

 

 

What is heredity?

ผลการค้นหารูปภาพสำหรับ heredity

 

Heredity is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents. Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection. The study of heredity in biology is genetics.

what is traits

Identical twins have exactly the same DNA, but they are not exactly alike. Each twin has his or her own personality, talents, likes, and dislikes. There are even diseases that appear in one twin but not the other, including arthritis, diabetes, autism, schizophrenia, cancer, and many others. The differences between identical twins don’t come from DNA—they all come from external factors.

Scientists often study twins to understand how genes and the environment work together to affect traits. They compare traits in identical twins, who have identical DNA, and fraternal twins, who share half their DNA, just like any siblings. If a characteristic appears more frequently in identical twin pairs than in fraternal twin pairs, then it has an inherited component.

5 heredity

EX.

1.Eye color

ผลการค้นหารูปภาพสำหรับ eye color

 

is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye‘s iris[1][2] and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris.[3]:9

In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma.[4] The appearance of blue and green, as well as hazel eyes, results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering.[5] Neither blue nor green pigments are ever present in the human iris or ocular fluid.[3][6] Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes.

The brightly colored eyes of many bird species result from the presence of other pigments, such as pteridinespurines, and carotenoids.[7] Humans and other animals have many phenotypic variations in eye color.[8] The genetics of eye color are complicated, and color is determined by multiple genes. So far, as many as 15 genes have been associated with eye color inheritance. Some of the eye-color genes include OCA2 and HERC2.[9] The earlier belief that blue eye color is a simple recessive trait has been shown to be incorrect. The genetics of eye color are so complex that almost any parent-child combination of eye colors can occur.[10][11] However, OCA2 gene polymorphism, close to proximal 5′ regulatory region, explains most human eye-color variation.[12]

2.Hair coloring 

 

ผลการค้นหารูปภาพสำหรับ hair color

 

 

or hair dyeing, is the practice of changing the hair color. The main reasons for this are cosmetic: to cover gray or white hair, to change to a color regarded as more fashionable or desirable, or to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching.

3.A hairstyle

ผลการค้นหารูปภาพสำหรับ hairstyle women

 

hairstylehairdo, or haircut refers to the styling of hair, usually on the human scalp. Sometimes, this could also mean an editing of facial or body hair. The fashioning of hair can be considered an aspect of personal groomingfashion, and cosmetics, although practical, cultural, and popular considerations also influence some hairstyles.[1] The oldest known depiction of hair braiding dates back about 30,000 years. In ancient civilizations, women’s hair was often elaborately and carefully dressed in special ways. In Imperial Rome, women wore their hair in complicated styles. From the time of the Roman Empire[citation needed] until the Middle Ages, most women grew their hair as long as it would naturally grow. During the Roman Empire as well as in the 16th century in the western world, women began to wear their hair in extremely ornate styles. In the later half of the 15th century and on into the 16th century a very high hairline on the forehead was considered attractive. During the 15th and 16th centuries, European men wore their hair cropped no longer than shoulder-length. In the early 17th century male hairstyles grew longer, with waves or curls being considered desirable.

4.dimple

ผลการค้นหารูปภาพสำหรับ A dimple

dimple (also known as a gelasin)[1] is a small natural indentation in the flesh on a part of the human body, most notably in the cheek or on the chin.

5.Human skin color

Human skin color ranges in variety from the darkest brown to the lightest hues. An individual’s skin pigmentation is the result of genetics, being the product of both of the individual’s biological parents‘ genetic makeup, and exposure to sun. In evolution, skin pigmentation in human beings evolved by a process of natural selection primarily to regulate the amount of ultraviolet radiationpenetrating the skin, controlling its biochemical effects.[1

ผลการค้นหารูปภาพสำหรับ Human skin color

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