Skin cells, divide in a continuous manner that makes new skin cells to replace the skin cells we lost. Cells regulate their division by cyclins. Some cells divide faster when it supposed to stop dividing and this will lead to cancer disease.
<u>Explanation:</u>
The process of cell division occurs for many reasons. A single cell is divided into two which in turn they will be divided into four and so on. This corresponds to the process of cell division and cell reproduction. Cell division is an unique characteristics in human beings. Interactions between signaling proteins produces checkpoints in the cell cycle to ensure that cells do not divide at improper times.
A protein named Cyclins plays a major role in the determination and the regulation of the cell division process. The division that occurs in the cell can be regulated by the this protein type. They acts as a switch for controlling the cell division process. They will signal the cells when to divide and when to stop. When any cell continues to divided even after it is signaled to stop they may lead to a disease called cancer. These are different form the normal cells because they will be having their own growth factors that controls their growth and they will lose the normal controls on the cell cycle.
Answer:
A XY or XY gamete fuses with a normal gamete (X or Y)
Explanation:
Meiotic nondisjunction is the phenomenon whereby chromosomes fail to separate during meiosis I or II. Meiotic nondisjunction leads to the formation of abnormal gametes I.e. gametes with additional or missing chromosomal piece.
The fusion of these abnormal gametes produced by nondisijuction with a normal gamete (X or Y chromosome). This leads to a condition called ANEUPLOIDY, which is a chromosomal disorder. In the case od Calix, XXY is an ANEUPLOIDY state that could have resulted because there was a fusion between a XX gamete and Y gamete or XY and X. The XY or XX gametes are produced as a result of nondisijuction.
Answer:
D. Aa
Explanation:
Given:
Jill (mother) is heterozygous for gene A --------- i.e Jill = Aa
Jack (father) who is homozygous recessive for gene A-------- i.e Jack = aa
Now if both cross and fertilization occurs, we have:
A a
a Aa aa
a Aa aa
The offsprings are (Aa, Aa, aa, aa)
Nondsijunction is the inability of homologous chromosomes to seperate properly during cell division. Now, we were told that this fertilization undergone nondisjunction in meiosis 1. Hence, both homologous chromosome move into the same daughter cells instead of different daughter cells because separation of homologous chromosome does not occur properly.
Therefore the result of these fertilization of a normal haploid sperm with an egg that had undergone nondisjunction in meiosis yields offspring with genotype Aa of their Mother (Jill).
A scientist must always try to avoid bias in scientific
experiments. It is important for scientist to avoid leaning into their bias
when trying to confirm their hypothesis. As much as possible the scientist
should be able to follow the scientific method to avoid bias.
