Answer:
Cancer is essentially uncontrolled mitosis of specialized cells.
Explanation:
As you said, cancer can control in any region of the body. As a matter of fact, a cancerous cell is produced in your body every 30 minutes and your immune system locates and kills it. Cancer is unpredictable and can happen in any specialized cell.
The bacteria which had mutation became resistant to the antibiotic and survived and keeps on increasing, promoting natural selection.
Explanation:
The bacteria rapidly divide, the chances of mutation in the gene increases manifold.
The strains of bacteria causing tuberculosis and staph infection got mutated at DNA level such that they became resistant to antibiotics when tested those susceptible did not survive. These mutations were not harmful to bacteria and the resultant bacteria survived.
These bacteria which survived and proliferated as the environment was in their favour.
Thus, Darwin's Theory of Natural Selection is acceptable here as it says if a mutation is occurring towards the increase in population, they will be selected ones.
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.
An enormous cloud of gas and dust that contracts due to gravity and forms stars is called a nebula.
