<span> Embryonic stem cell research is kind of a dead area now since there is no way to control the differentiation. Most research is being done on adult stem cells to help map and control the differentiation process.
Stem-cells from aborted fetuses - The government doesn't sponsor this, if it is done it is by private companies not located in the USA. You could try researching umbilical cord stem cells to be somewhere near your topic. They come from the afterbirth of normal deliveries.
You could do a much easier report by covering cloning of mice through stem-cell technology. It is happening and helping scientists understand diseases. </span>
Petroleum Products
Petroleum and its products are mainly composed of carbon polymers (chains), as the backbone, with different structural and functional groups. Plastic, for example, is made of polypropylene and polybutylene which is mainly made of carbon atoms, whose monomers are linked in a chain to form polymers that make up the products.
Synthetic rubber on the other hand is made of copolymers of carbon and other addictives such as styrene. Synthetic fiber is made of nylon that is composed of a copolymer between carboxylic acid and amides.
Answer:
Each mutant would be mated to wild type and to every other mutant to create diploid strains. The diploids would be assayed for growth at permissive and restrictive temperature. Diploids formed by mating a mutant to a wild type that can grow at restrictive temperatures identify the mutation as recessive. Only recessive mutations can be studied using complementation analysis. Diploids formed by mating two recessive mutants identify mutations in the same gene if the diploid cannot grow at restrictive temperature (non-complementation), and they identify mutations in different genes if the diploids can grow at restrictive temperature (complementation).
Explanation:
Recessive mutations are those whose phenotypic effects are only visible in homo-zygous individuals. Moreover, a complementation test is a genetic technique used to determine if two different mutations associated with a phenotype colocalize in the same <em>locus</em> (i.e., they are alleles of the same gene) or affect two different <em>loci</em>. In diploid (2n) organisms, this test is performed by crossing two homo-zygous recessive mutants and then observing whether offspring have the wild-type phenotype. When two different recessive mutations localize in different <em>loci</em>, they can be considered as 'complementary' since the heterozygote condition may rescue the function lost in homo-zygous recessive mutants. In consequence, when two recessive mutations are combined in the same genetic background (i.e., in the same individual) and they produce the same phenotype, it is possible to determine that both mutations are alleles of the same gene/<em>locus</em>.
The right answer is The cells are damaged.
Take the example of skin cells.
The skin consists of two tissues:
* the outermost, the epidermis, resting on a vascularized connective tissue,
* the dermis.
In the epidermis, which includes several layers of cells, the outer layer is formed of dead cells that are desquamating and are constantly being replaced from proliferating basal cell cells. So, in normal conditions, the epidermis is in constant renewal.
On the other hand, when accidentally, the upper parts of the epidermis are damaged, for example, a slight abrasion or of a burn, the destroyed portion is regenerated (replaced) thanks to an accelerated proliferation of basal epidermal cells .
