HD is called an autosomal dominant disorder because only one copy of the defective gene, inherited from one parent, is necessary to produce the disease. The genetic defect responsible for HD is a small sequence of DNA on chromosome 4 in which several base pairs are repeated many, many times.
Carbon dioxide cannot pass through the protective waxy layer covering the leaf (cuticle), but it can enter the leaf through an opening (the stoma; plural = stomata; Greek for hole) flanked by two guard cells. Likewise, oxygen produced during photosynthesis can only pass out of the leaf through the opened stomata.
Light-independent reactions (also called dark reactions): ATP and NADPH are rich energy sources, which drive dark reactions. During this process carbon dioxide and water combine to form carbohydrates like glucose. This is known as carbon fixation. Photosynthesis in the future. Photosynthesis generates all the breathable oxygen in the atmosphere, and renders plants rich in nutrients. But researchers have been looking at ways to further harness the power of the process.