Answer:
B. The father did not contribute a sex chromosome to his daughter due to nondisjunction of the sex chromosomes. The daughter is XO and her only X chromosome came from her mother, who was a carrier.
A.The mother's X chromosomes failed to separate during meiosis, and the daughter inherited two X chromosomes with the Lesch-Nyhan mutation. The father contributed no sex chromosomes.
Explanation:
As seen in the question above, a little girl was diagnosed with Lesch-Nyhan syndrome, which is an X-linked recessive condition caused by a mutation in the HPRT1 gene responsible for purine metabolism.
The little girl's parents do not have the syndrome, and no one in the little girl's paternal family presented this syndrome, however, we know that the maternal grandfather of the little girl's mother had the syndrome, which means that it was the mother's genetic material that contributed to the development of the syndrome in the little girl. This was because the little girl did not receive any X chromosomes from her father, but she inherited the two X chromosomes from her mother that coded for the Lesch-Nyhan mutation. This happened because the mother's X chromosome disjuction did not occur during meiosis I.
As shown above, the father did not contribute any sex chromosomes to his daughter, which means that the daughter is XO and her only X chromosome came from her mother, who was a carrier.
Answer:
Blood Brain Barrier(BBB)
Explanation:
This is a biological interface of special endothelial cells of astrocytes, pericytes , capillaries, neurons and other structures, acting as a physical barrier or gate separating the Central Nervous system from the peripheral blood circulations. Thus it formed a tight junction serving as a physical barrier to selectively regulate the entrance of substances from the cerebral blood flow into the brain, therefore maintaining homeostasis of the brain.
From above any substances absorbed into the blood stream irrespective of the mode of entry are transported through the BBB, and are selectively regulated to enter the brain cells by the BBB's interactions with the blood vessels, hormones etc.
Basically it allows the passage of nutrients, a few drug, hormones and resists certain toxins and pathogens for the brain homeostasis.
Photosynthesis, how plants survive. Sunlight is absorbed.
B - The environment within the cell is stable.
Homeostasis is when your body works to maintain equilibrium (balance) so within a cell, the cell would be stable
He should ask for spicy tuna rolls that do not have red algae in them.
