Genomic imprinting is a process wherein a gene is differentially expressed depending on whether it has been inherited from the mother or from the father and occurs only in sexually reproducing placental mammals.
Imprinting occurs when one of the gene’s parental alleles is silenced throughout the embryonic development of the individual by an alteration in parental DNA made during parental gametogenesis thus allowing the other parental allele expression during embryonic development. DNA methylation is one of the mechanisms by which imprinting occurs (the addition of a CH3, or methyl, group to specific regions of DNA). These process has led to disease syndromes and tremendous implications for development and a large attributes in adults.
Given the age of the meteorite is 4.5 billion years old with 78 atoms of lead-206 the answer should be B. 156. The half-life of uranium-238 in order to decay into lead-206 is 4.46 billion years, which means that the original number of atoms is 156.
The first step in the Scientific Method is to make objective observations. These observations are based on specific events that have already happened and can be verified by others as true or false. Step 2. Form a hypothesis.
