Table of Contents
What is DNA made of?
DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code.
Why is DNA so important?
DNA is vital for all living beings – even plants. It is important for inheritance, coding for proteins and the genetic instruction guide for life and its processes. DNA holds the instructions for an organism's or each cell's development and reproduction and ultimately death.
Who discovered DNA?
Many people believe that American biologist James Watson and English physicist Francis Crick discovered DNA in the 1950s. In reality, this is not the case. Rather, DNA was first identified in the late 1860s by Swiss chemist Friedrich Miescher.
How many genes are in human DNA?
There are an estimated 20,000-25,000 human protein-coding genes. The estimate of the number of human genes has been repeatedly revised down from initial predictions of 100,000 or more as genome sequence quality and gene finding methods have improved, and could continue to drop further.
What is the shape of DNA?
The DNA molecule is shaped like a ladder that is twisted into a coiled configuration called a double helix. The nitrogen bases form the rungs of the ladder and are arranged in pairs, which are connected to each other by chemical bonds.
Where Is DNA Found?
Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
How many chromosomes are in a gene?
Genes are contained in chromosomes, which are mainly in the cell nucleus. A chromosome contains hundreds to thousands of genes. Every human cell contains 23 pairs of chromosomes, for a total of 46 chromosomes.
How many DNA is in a chromosome?
Human cells contain two sets of 23 chromosomes, one set inherited from each parent (46 total). These chromosomes are large "chunks" of DNA wound tightly together, and range in size from 51 million to 245 million base pairs each. As a whole, the whole human genome is 3.3 billion base pairs long!