Answer:
By preventing the synthesis of DNA halting cell growth.
Explanation:
Fluorouracil and methotraxate prevent the synthesis of the neucleoside Thymidine thus preventing DNA replication and elongation. Methotraxate has a structure analogous to Folic acid which is important for thymidine synthesis. Thus, it acts as a competitive inhibitor on dihdrofolate reductase an enzyme that is essential for tetrahydrofolate formation, a folic acid derivative.
Fluorouracil acts by inhibiting thymidylate synthase which catalyses an essential step in Thymidine synthesis.
A situation where friction would be desirable is rubbing your hands together to make them warm in the winter time.
Phenotypically and genotypically there are only two different ratios. If you think of a Punett square...
<span>You could say that a pea plant with the trait for the dominant color green (G) could also carry the recessive trait for yellow (g). So let's say you mate a dominant green, (Gg) with another dominant green, (Gg). You would get 1 (GG), 2 (Gg) and 2 (gg). </span>
<span>Phenotypically (as in physical traitwise), the ratio is 3:1 because you have 3 green colored peas and one yellow. </span>
<span>Genotypically (as in traitwise), the ratio is 1:2:1, because you have 1 (GG), 2 (Gg) and 1 (gg). </span>
<span>So although it's random, for any specific trait there are only 4 different outcomes.</span>
