Cooking an egg is a set of chemical changes because chemical bonds are broken and new ones are made, resulting in the formation of new substances. In this case many of the bonds broken are those which cause the egg's proteins to be folded into a globular shape. The protein chains unfold and become entangled causing the setting effect. This is often called denaturing. Whether or not a change can be reversed has no bearing on whether it is chemical or physical. This particular change is almost impossible to reverse because of entropy effects but that simply isn't true of all chemical reactions, and there are many physical changes which are hard to reverse.
Accoring to the Chargaff's first rule of base pairing, each of the four nucleotide bases has its own complimentary match, that it always bids with.
So, Adenine always bonds with Thymine and Cytosine always binds with Guanine.
If you know the concentration of one base, in our case Cytosine, then you can easily calculate the percentage of other bases.
Since Cytosine and Thymine are always paired, there is an equal amount of both of them -16%.
So, 16% C + 16G = 32% of the whole DNA.
This means that the other two base pairs A and T make up to 68% of the DNA.
Half of the 68% is Adenine = 34% and half of it is Thymine- 34%.
So, the percentages of base pairs in the DNA sequence are :
16% C
16% G
34 % A
34 % T
- The study was unique because the unexpected nature of extreme weather events makes the responses to such events is hard to be studied.
- But Campbell-station stressed on the effects of the natural selection of green anole lizards after the cold weather event that happened during the winter in the southeastern united state.
- He was able to collect data after and before the extreme weather and was able to measure selection at three levels:
1- gene expression.
2- genetic variation.
3- whole animal function.
Prior knowledge allows you to make a well-informed hypotheses and a better-planned experiement.