B. DNA is heated to separate strands
<span>First.PCR reaction</span>
<span>When you are pregnant, you do not ovulate because you have already fertilized an egg and it is embedded into the uterus where it is growing into a baby. The body knows this, so it does not shed the uterine lining. The shedding of this lining is triggered by hormones which change when the body is pregnant. During pregnancy, a large amount of progesterone is initially produced which helps to prevent the lining from shedding. If you are not pregnant, your progesterone level will begin to decline at the end of your cycle, triggering the shedding of the lining and the period. Birth control pills alter your hormones to mimic a pregnant state. This will prevent the body from releasing an egg and then shedding the uterine lining.</span>
<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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