Vesicles form naturally during the process of secretion(exocytosis), uptake (phagocytosis and endocytosis) and transport of materials within the cytoplasm. Alternatively, they may be prepared artificially, in which case they are called liposomes.
Answer:
D) Each parent contributes one allele for this trait
Explanation:
All traits of individuals are determined by specific genes of that trait. For example, there is a certain gene for height, certain gene for eye color, face shape etc.
Genes are the units of hereditary, and for every trait there is one gene in every organism. However, one gene is present in two alternative forms called alleles in an organism. For example: There is a trait height, a person has two alleles for the height gene, one allele is for short height, and other allele is for tall height. The trait of tallness is dominant over the trait of shortness, Therefore, this person will have tall height.
Now the alleles are transmitted from parents to offspring. Every parent contributes one allele for a specific trait, in the process and transmit it to offspring.
The allele which will be dominant will be expressed while the one that is recessive will e suppressed.
Therefore, option D is the right answer.
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Answer:
B. G1, S, G2, Mitosis, Cytokinesis
Explanation:
G1 is the first stage of the cell cycle, and it is essential for cell growth.
Next, the S (Synthesis) phase occurs. This phase involves DNA synthesis to prepare the cell for division.
G2 is the next phase, and it involves preparing and growing the cell for mitosis.
Mitosis is the next stage, where the cell divides into 2.
Lastly, Cytokinesis occurs after mitosis, and it creates the two daughter cells.
So, the correct answer is B. G1, S, G2, Mitosis, Cytokinesis
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.
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