In the pedigree shown, the presence of a dominant autosomal genetic disorder is indicated by a shaded box. this is an autosomal inheritance, not a sex-linked trait.

part a: determine whether or not either of the parents (1 or 2) could be homozygous for the trait in question. explain your answer in 1-2 complete sentences. (2 points)

part b: “person 8” does not want to see the disorder passed on to his offspring. he does, for certain, what to get married and have children biologically. if you were a genetic counselor, what advice would you give to him about his odds on having a child with the genetic disorder if he:

(a) married a woman who is heterozygous for the condition and

(b) married a woman who does not have the genetic disorder. (2 points)

Part A:

No, neither of the parents could be homozygous for the trait.

If any of the parents were homozygous for the disorder, then all the offspring would inherit the disease, but offspring 5 did not get the disease. Hence, none of the parents was homozygous.

Part B:

It would be most appropriate to marry a woman who does not have a disease.

It is because it reduces the probability of offspring to have a disease.

When both the parent are heterozygous only 1/4 chances are there that the offspring would not have a disease.

In contrast, if the mother is homozygous recessive and father is recessive then 2/4 chances are there that the offspring would not have a disease.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!