Molecular Clocks
Research and write a brief essay describing a specific example of when molecular clocks were used to
determine when two species diverged from each other. Explain how this was done.
determine when two species diverged from each other. Explain how this was done.
Your essay should be at least 2 paragraphs long. Remember to write in complete sentences, using appropriate grammar, punctuation, and spelling. Be sure to cite any sources that you use.
Note: If you do not personally believe in evolution, that is fine. However, I still need you to write this essay explaining how supporting scientists believe molecular clocks have been used to show when two species diverged from each other.
here is the material.
The world around us is full of interactions between different types of matter. All of these interactions are caused by one of four fundamental forces; gravity, electromagnetism, weak nuclear force, and strong nuclear force.
Gravity
Gravity is the attractive force felt between any two objects. The magnitude of this force is determined by the mass of the objects and the distance between them. While there is gravity between small items like you and your best friend, your masses are so small that this force is undetectable. This force is responsible for the Earth orbiting the Sun, objects falling to the ground, and the ocean tides.
Electromagnetism
Electromagnetism is the force responsible for the attraction and repulsion between charged particles and magnets. As all of matter is made up of charged particles (protons and electrons), this force is responsible for almost all of the interactions between matter. This force works on the submicroscopic scale (proton and electron interactions) and the macroscopic scale (interactions between people and the things around them).
Strong Nuclear Force
The strongest of the four fundamental forces, the strong nuclear force is responsible for holding together the nucleus of an atom. The repulsive forces between protons is quite large, and this force overcomes that. However, this force is very short ranged and can only be felt within the atom.
Weak Nuclear Force
The weak nuclear force is also very short ranged and is responsible for nuclear decay. This force helps unstable atoms to decay into more stable nuclei. The force is responsible for the emission of radiation and energy during nuclear reactions.
| Force | Magnitude | Range |
| strong nuclear | strongest force | within a nucleus |
| electromagnetism | much weaker than strong nuclear | infinite |
| weak nuclear | much weaker than electromagnetism | 0.1% the diameter of a proton |
| gravity | weakest force | infinite |
One of the current goals in physics research is the unification of these four forces. Two have them have already been unified, electromagnetism and weak nuclear are together called the electroweak force. There are several theories allowing for
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The theory of evolution states that organisms change over time. Evolution can mean large changes, such as when species split from each other, and small changes like the shape of a bird’s beak. While evolution can not be empirically proven, there is much fossil and DNA evidence to suggest that it is true.
Molecular Clocks
The teacher’s domain video above states that humans and chimps had a common ancestor several million years ago. This timeline was calculated using molecular clocks. Certain genes undergo regular changes to the base pairs in their DNA, such as one gene that codes for a part of blood changes at a rate of .56 base pairs every billion years. When portions of DNA change at regular rates such as this they can be used as a type of clock to show how long ago species diverged by counting how many base pairs are different. If two species have only 2 base pairs different in the previously mentioned gene then they must have diverged from a common ancestor about 4 billion years ago.
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Relative Velocity
For anything other than light, the velocity of the source and the velocity of the observer are both very important.
If a person is riding in a car going 30 mi/hr and a second car goes by at 40 mi/hr in the same direction, the velocity of the second car is 10 mi/hr relative to our person in the first car or 40 mi/hr relative to the road. So what you are measuring relative to is very important.
If a person is riding in a car going 30 mi/hr and a second car goes by at 40 mi/hr in the same direction, the velocity of the second car is 10 mi/hr relative to our person in the first car or 40 mi/hr relative to the road. So what you are measuring relative to is very important.
Einstein’s Theory of Special Relativity
One of the assumptions of Einstein’s theory goes against relative velocity in saying that the speed of light always appears to be 3.0 x 10
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m/s, regardless of the velocity of the source or the observer. Basically, nothing can move faster than light. This leads to the idea of time a fourth dimension and the development of space-time.
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