0
What else can I help you with?
Why are mouse ES cells Cultured on Irradiated Mouse Embryonic Fibroblasts?
Mouse embryonic fibroblasts are inactivated by either chemical (Mitomycin-C) or radioactive (Cs-137) means before culturing with embyronic stem cells to prevent the fibroblasts from merging with the stem cells and creating a chimeric cell.
Why is Down syndrome a recessive trait?
Down syndrome is not a recessive trait. Down syndrome is caused by a third copy on chromosome 21 and is present at conception or shortly after. It is mostly a random (and relatively common) occurrence, unless it is of the translocation type which is rare and genetic. Therefore it is NOT a trait.
How to get rid of a cyst?
A cyst is a membrane sac which often encloses something within the sac. For example, a cyst may be hollow or may be filled with fluid. Another type of cyst may contain tissue or other types of cells. A cyst forms for a wide range of reasons but one of the most common reasons is that a cyst is the body's attempt to enclose and literally "wall off" something that could cause illness, infection, or another problem. For example, in some pregnancies, the embryo does not form correctly and the body will "wall off" and enclose the embyronic sac within a "cyst". That type of cyst is surgically removed and when it is sent to the lab, the technicians actually find parts of an embryo or embryonic cells within the cyst. In another less dramatic example, some people will get a small moveable cyst on a knuckle which can cause pain if it is resting on a nerve. This kind of cyst is most often simply full of fluid.
Is it true that all calico cats are females?
To put it simply, calico cats are caused by the random conversion during embyronic development of X chromosomes into Barr bodies. When you have a female cat, you have two X chromosomes (XX). When the female cat embryo is a morula (earliest recognizable embryo), each cell in the embryo randomly inactivates one X chromosome and passes this inactivation onto daughter cells in the same line. This is what allows for the spotted appearance of calico cats, as we are assuming momma kitty and papa kitty had different coat colors transferred to the embryo through the X chromosome. This random inactivation is also why females are typically not color blind. Color blindness is caused by an inability to perceive certain colors due to a deficient protein that has its DNA inside the X chromosome. Females have two X chromosomes, and one of them is randomly selected to be used in the development of each focal area of the eye. If the female had a color blind father, this means each eye would be roughly half color blind, and since half is enough to perceive color well, unaffected. A female could indeed be color blind if she received "bad genes" from her mother as well, but it's a much rarer circumstance. You do not see the calico patterns with a normal male (XY) cat because the X chromosome does not become inactivated in male animals. However, cats are susceptible to the same genetic disease we are. In one particular disease, two cells fail to separate their X chromosomes during Meiosis (an event called Nondisjunction). This cat hence receives two X chromosomes from mom, and say in the case of a male, a Y from dad. This cat's resultant genotype is XXY and the cat has Klinfelter's Syndrome. The cat appears male (i.e. has a male phenotype) but he really has two X chromosomes. This tends to be why male calico cats are much rarer and are also sterile To make things simple its very rare to have a male calico cat. And yes male calico cats are sterile. A regular female cat has XX chromosomes and a regular male cat as XY chromosomes. A male calico cat would have XXY chromosomes which in human form this would be called Klinefelter's syndrome. Which makes the male calico cat sterile.
