載入中... 相關課程 Back Genetics 101 Part 2: What are SNPs? 登入觀看 ⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles. Genetics 101 Part 2: What are SNPs? : Learn about the variations in human DNA called SNPs, and how they can be used to understand relationships between people. 上傳學習單 下載學習單 相關課程 0 / 750 That entire set of 23 human chromosomes is called a genome. The human genome is composed of 3 billion base pairs. Variation at a single base pair is called a SNP, or single nucleotide polymorphism. When the body makes new cells, it doesn't make many mistakes, but nobody is perfect. Sometimes, when the genome is copied, to make a new cell, a single base pair gets lift out, added, or substituted. Single base pair substitutions create SNPs. There're around 10 million SNPs in the human genome, which account for many of the genetic differences between you and everyone else on the planet. Some SNPs account for differences in appearance, others can affect how we develop diseases, or respond to drugs. Most SNPs, however, seemed to lead to no observable differences between people at all. Since variance are passed down from one generation to the next, the number of differences between your DNA, and your neighbors can tell you how closely you're related to each other.