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 Kidneys.
The plasma passes through the kidney where it is filtered, a special filtration unit called "glomeruli" and then excreted as a low molecular weighted product into the urine. The purpose of our urine is to secrete waste products from the body. So you can see how the glomerular filtration mechanism of the kidneys plays a major role in the function of our bodies. The primary function of our kidneys is to filter out all the "bad stuff" in lamest terms.
-Current Medical Student (College Level)
Answer:
the genotype of the parent guinea pigs are as follows:
RrBb (rough, black) and Rrbb (rough, white)
Explanation:
Since the phenotype of smooth coat is present in the offspring, the parent genotype cannot have RR alleles for their coat. Similarly, the rough, black parent cannot have BB alleles in its genotype because that will not yield a white coat color in its offspring.
After making the dihybdrid cross, the probability obtained for each phenotype is given below:
rough black: 
rough white:
smooth black: 
smooth white:
Hope that answers the question, have a great day!
Scientists classify rocks based on texture, composition, and how the rocks formed.] Rocks are classified by how they formed.
Answer:
b. forward mutation, suppressor mutation
Explanation:
When the nucleotide sequence of an organism is altered, it is called as mutation. It can be caused by DNA damage or replication errors. In forward mutation, the wild type allele is converted to a mutant version such that the gene product is non functional or its not produced at all. Suppressor mutation is the second mutation which reverses the phenotypic effects of the previous mutation. This process is called as synthetic rescue.
Since here gene X was converted into a mutant form by the mutation, it had undergone forward mutation. When gene Y was mutated, the function of gene X was restored which ultimately also restored the phenotype hence it is an example of suppressor mutation.
