DNA polymerases add nucleotides to the 3′ end of a polynucleotide chain. ... To initiate this reaction, DNA polymerases require a primer with a free 3′-hydroxyl group already base-paired to the template. They cannot start from scratch by adding nucleotides to a free single-stranded DNA template.
How is DNA replicated? Replication occurs in three major steps: the opening of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment. During separation, the two strands of the DNA double helix uncoil at a specific location called the origin.
Blood enter the right atrium of the heart via the vena cava (superior and inferior)
The right atrium contracts to push the blood into the right ventricle through the triscupid valve
The contraction of the right ventricle pushes the blood through the pulmonary valve to the pulmonary artery which carries it to the lungs to be oxygenated
After oxygenation, the pulmonary vein brings blood to the left atrium
Contraction of the left atrium pushes the blood through the mitral valve into the left ventricle
The left ventricle contracts to push the blood through the aortic valve, into the aorta, which carries the blood through the body.
