1.) BrdU is used to trick cells into using it, rather than thymidine, in their DNA. This occurs during the S phase of the cell cycle. The DNA formed with BrdU has unique staining properties. BrdU causes light and dark regions to appear on chromosomes and we can then see crossing over. One round of duplication with BrdU causes no discernible differences in chromosomes. The second round of duplication is where the differences are seen. One of the sister chromatids will look visually normal while the other does not.
2.) A small number of changes in DNA sequence can be beneficial. Sometimes the changes go unnoticed for several generations but eventually accumulate to create a unique trait in an individual. These changes are part of what leads to diversity in organisms. The random mutation in DNA could possibly code for such a unique trait that the organism can benefit from it and aid in the organisms survival.
3.) Protein folding disorders could potentially ...view middle of the document...
This would effectively eliminate cell reproduction in the cancer cells.
5.) Males are constantly producing sperm through spermatogenesis, most of their life. Women are born with all the eggs they are ever going to have. Most of them die before they can be used. The primary oocyte is also arrested in development in prophase I at birth and not active again until after puberty. This extended phase and overall decreased output from females leads to a higher failure rate.
6.) Primary nondisjunction occurs during meiosis. This type of nondisjunction leads to abnormal chromosomal division which results in gametes with more or less than chromosomes than normal. Secondary nondisjunction occurs in individuals who already experienced primary nondisjunction. No individual would survive with a 0Y chromosome. The X chromosome houses many important genes vital to survival, not just sex determining genes.
7.) Calcium is easily transported into and out of cells and diffuses through various fluids rather easily. Calcium is just the signal, the receptors are what makes it so universal. Many different types of receptors are able to respond to calcium to perform various functions. Vesicles in the presynaptic terminal respond to Ca2+ by releasing neurotransmitter, Ca2+ also aids in muscle contraction by stimulating the electrical potential for the muscles to begin contraction.
8.) Vasopressin acts to retain body water by increasing cellular uptake of water in the nephrons of the kidney. This reduces water volume in the urine and increases it in the blood. Mutant vasopressin receptors could bind to the vasopressin and not be able to let it go. This would eventually cause all of the receptors to be filled. This would cause a shortage of aquaporins due to the receptors being under stimulated. This is what causes nephrogenic diabetes insipidous.
9.) A gain of function mutant happens when a mutation creates a new allele. The new allele will bring a new function that is beneficial to the organism. The way gain of function mutation are expressed is that a heterozygote wight he new allele and the wild type allele for that trait, will express the new allele instead of the wild type.