What is the effect of this substitution mutation on the amino acid sequence?

Substitution mutations just switch out one or more bases for different ones. Substitution mutations can cause many kinds of mutations. Some of these include nonsense, missense, and silent mutations. All of these depend on whether or not the new base codes for an amino acid different than the original.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.