They occur in germ cell DNA, which are the cells that create sperm or Ova. For every 85 million nucleotides assembled in DNA during human sperm or Ova production, One will be a mutation
<span>DNA polymerase is the enzyme that connects new nucleotides and proofreads them into separate DNA strands.
This process is part of DNA replication. A cell's DNA is replicated before a cell divides. The two strands of a DNA molecule have complementary base pairs. Each strand in the pair consists of a nucleotide sequence which is able to provide the information to duplicate itself. Before the duplication occurs, the length of the DNA that is about to be copied must be unwound and the two strands must be separated. This is done by breaking the weak hydrogen bonds that link the pairs together. They must then be kept apart from each other to expose the bases so that the new nucleotide partners can bond to them. DNA polymerase is the enzyme that moves along the exposed DNA strand and joins the new nucleotides to manufacture a new DNA strand that is a duplicate of the original</span><span>
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Fixation
Nitrogen is converted from atmospheric nitrogen (N2) into usable forms, such as NO2-, in a process known as fixation. The majority of nitrogen is fixed by bacteria, most of which are symbiotic with plants. Recently fixed ammonia is then converted to biologically useful forms by specialized bacteria
Animals have so many different enzymes to digest their food they eat variety of food in their diet so specif enzymes are needed to digest each type of food
DNA replication needs to occur because existing cells divide to produce new cells. Each cell needs a full instruction manual to operate properly. So the DNA needs to be copied before cell division so that each new cell receives a full set of instructions!
