Answer and Explanation:
The Huntington disease is caused by a mutation in the gene that codifies for the Huntingtin protein (Htt). The mutation produces an altered form of the protein leading to the neuron´s death in certain areas of the brain.
The Huntington disease characterizes for being,
- Hereditary, passing from generation to generation. To express the disease, a person must have been born with an altered gene.
- Autosomal, affecting men and women equally, because the mutated gene is located on an autosomal chromosome.
- Dominant, which means that by getting only one copy of the altered gene coming from any of the parents, the receiving person will express the disease. The mutation in the gene dominates over the normal gene copy.
- Expressed by heterozygosis. Most people affected by the disease are heterozygous, with a normal copy and a mutated copy.
There are just a few cases all around the world (3% approximately) in which the disease is expressed with no family history. The progenitors are not affected by the mutation. These cases are very rare and are called <u>"de-novo" mutations.</u> A new mutation is spontaneously produced and it is not inherited from any of the parentals. It consists of an increase in the number of CAG repetitions. In a normal person, the number of CAG repetitions is less than 35. When there are 40 or more repetitions it occurs the disease. But when there are between 35 and 39 repetitions, the penetrance of the disease is incomplete. This is a "gray zone". Those alleles that fall in the gray zone are unstable and might produce the HD. Individuals with these unstable alleles have a tendency to increase the number of repetitions from generation to generation until the number reaches 40 repetitions and the person expresses the disease. This <u>usually occurs in the paternal germinal line</u>, as it is particularly unstable in sperm and probably meiosis greatly affects their instability, causing an increase in the number of CAG repeats.
The chamber is the left atrium.
The lungs help exchange the deoxygenated blood which are full of wast materials into oxygenated and blood full of nutrients. These oxygenated blood are then transported through the pulmonary vein, the only vein in the body which transports oxygenated blood. These blood are then transported back into the heart, which is the left atrium specifically.
Those blood is then pushed down to the left ventricle, and then pumped to the whole body (except lungs), in order to keep the body functioning by providing oxygen and nutrients for cellular respiration.
Meanwhile, the deoxygenated blood are received by the right atrium, and is then transported back to the lungs for exchange again, through the right ventricle and pulmonary artery.
I believe that you're question is referring to homeostasis
The answer would be c. only plant cells and some single cell organisms photosynthesize.
Since this is college level biology, you should know that red blood cells do not contain organelles... therefore it does not do a,c, and d. So, the question should say, which of the following is correct.
