Dna base pairs how many

Attached to each sugar is one of four bases--adenine A , cytosine C , guanine G , or thymine T. The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.

Base pair describes the relationship between the building blocks on the strands of DNA. And each of the nucleotides on one side of the strand pairs with a specific nucleotide on the other side of the strand, and this makes up the double helix. So for example, if there's a G on one side of the strand, there will always be a C on the other.

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Cancer Health Disparities. Childhood Cancers Research. Global Cancer Research. Cancer Research Infrastructure. The bases have different shapes and pair up together in specific combinations: A pairs with T, and C pairs with G to make base pairs. Put three billion of these base pairs together in the right order, and you have a complete set of human DNA—the human genome. This amounts to a DNA molecule about a metre long. You have two copies of the genome, one from your father and one from your mother.

The metre-long sequence is cut up into 23 bits, which are then tightly packaged as chromosomes in each of our microscopic cells. No two people have exactly the same DNA sequence. Identical twins are a bit of an exception to this rule, because they came from a single egg that split into two, forming two copies of the same DNA.

Three billion is a lot of base pairs. Rather, within this long string, there are distinct sections of DNA that affect a particular characteristic or condition. These stretches of DNA are known as genes. Their base pair sequence provides the instructions for bringing together the right amino acids in the right order to build a protein. Some genes are small, only around base pairs; others contain over one million.