Genetics questions

Interbreeding between Neanderthals with modern humans took place several times. Neanderthal-derived DNA was found in the genome of contemporary populations in Europe and Asia, it accounts for 1–4% of modern genomes. Neanderthal genes are absent from most modern populations in sub-Saharan Africa.

Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine. Uracil is a demethylated form of thymine.

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females.

Gregor Mendel, known as the "father of modern genetics," was born in Austria in 1822. A monk, Mendel discovered the basic principles of heredity through experiments in his monastery's garden. He was engaged in research on the inheritance of the traits of peas.

Most cases of Down syndrome are caused by trisomy 21. Occasionally, the extra chromosome #21 or a portion of it is attached to another chromosome in the egg or sperm; this may cause "translocation Down syndrome." This is the only form of Down syndrome that may be inherited from a parent.

The first genetically modified animal to be commercialized was the GloFish, a Zebra fish with a fluorescent gene added that allows it to glow in the dark under ultraviolet light. It was released to the US market in 2003. GloFish available in pet stores are now sold in bright red, green, orange-yellow, blue, pink, and purple fluorescent colors. In the European Union, the placing on the market and breeding of genetically modified animals is prohibited.

The U.S. Supreme Court in 2013 held that human DNA was a "product of nature", a basic tool of scientific and technological work, thereby placing it beyond the domain of patent protection. It struck down patents held by Myriad Genetics Inc, a Utah company, on two genes linked to a higher risk of breast and ovarian cancer. The ruling represents a major shift in the law, overturning three decades of patent awards by the US government and could have a profound effect on the biotechnology and drug industry.

Prader–Willi syndrome is a genetic disorder due to loss of function of specific genes. Beginning in childhood, the person becomes constantly hungry, which often leads to obesity. Also, mild to moderate intellectual impairment. Often, the forehead is narrow, hands and feet are small, height is short and skin is light in color.

DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it "nuclein". In 1878, Albrecht Kossel isolated the non-protein component of "nuclein", nucleic acid, and later isolated its five primary nucleobases.

Telomeres are an essential part of human cells that affect how our cells age. Telomeres are the caps at the end of each strand of DNA that protect our chromosomes, like the plastic tips at the end of shoelaces. Over time, due to each cell division, the telomere ends become shorter. They are replenished by an enzyme, telomerase reverse transcriptase.stic tips at the end of shoelaces.