Molecular Clocks

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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.  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 nuclearinfinite
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
 
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.
 
 
Click HERE to watch a video about the evolution of humans.
 
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.  


 
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.  
 
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 108 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.
 
 

Click here to join Tim & Moby at BrainPop© as they explore relativity.

BRAINPOP© DIRECTIONS: 

1)  Click “Play Movie” to begin the movie. You can click “full screen movie”to watch the movie in a larger screen.

 

2)     Check out the “Q&A” to review important ideas about relativity.

3)     Want to learn some more? Go to “FYI” to learn cool facts about relativity.

4)     How well do you understand relativity?  Take the “Review Quiz” to find out. This is not an assessment – just practice!  Your score is not recorded. 

 

5)     Close the window and return here to learn more!

 

As technology and medicine have advanced, the field of biomedical ethics has come to the forefront with many controversial topics, such as the rationing of health services, euthanasia and the definition of death, and reproductive technology. The purpose of this section is just to bring to light some of the questions raised by these advances, not to suggest answers to these questions.
 
Rationing Health Services
 In terms of health and healthcare there are a great number of inequities. Some people are rarely ever sick, while others need constant care just to survive. With a limited number of doctors is it fair to allow a few patients to take so much of their time, even if they will never get better? Is it fair that people with more money and better insurance go to better hospitals and see better doctors? What about organs? Is it fair for a recovered alcoholic to get a new liver to replace the one they destroyed while a child dies for lack of one? These questions have no easy answers, which is one reason health care law is so difficult to write. However, these issues impact people and society as a whole on a daily basis, from the uninsured waiting hours to be seen in a hospital to patients dieing due to lack of availability of organs for transplant. 
 
 
Who Decides What is Death?
Another tough topic is death, and what is clinically dead. With today's advanced medical technology, life can be sustained in a body long after brain activity has stopped. Does that person's family have the right to sustain that life? Sometimes people return from comas long after their family has been told brain death has occurred. Does science have any right to say what defines death in a still living body?
 
Euthanasia (meaning "good death") is on the other end of the spectrum. While many people support the right for a person to choose when to end their life, particularly when diagnosed with a terminal disease, this practice can lead to a slippery slope. If it is alright to assist the terminally ill with their deaths, what about the chronically ill, or the severely handicapped? There are people that believe that those not born "perfect" should not have been born at all. Some people believe that allowing euthanasia could cheapen the sanctity of life, and where does that leave society?
 
 
Reproduction
There is also the opposite problem--the argument over when life begins--brought about by the issue of abortion. A closely related issue is stem cell research. Stem cells have the possibility of curing so many diseases, but gathering stem cells currently requires the death of an embryo. Does the benefit outweigh the cost?
 
Click HERE for a video about the benefits and difficulties of stem cell research.
 
Another issue surrounding reproductive technology is genetic selection. It may soon be commonplace to be asked what gender you'd prefer for your child and what color hair you want them to have. However, genetic diseases could also be all but eradicated. Even now though, genetic screening brings up some issues. Who decides what disease are bad enough for a fetus to not get to be born?
 
Click HERE for an interactive with more information about genetic selection.
 
 
Cloning
In 1996 the cloning of Dolly the sheep sparked a wildfire of debate on the ethics of cloning. While cloning has been used for years in agriculture, the idea of cloning animals and maybe eventually people has many concerned. Cloning organs so that more are available for transplants would be a huge benefit, but losing the diversity of life by cloning whole organisms could cause evolutionary problems. 
 
 

Click here to join Tim & Moby at BrainPop© as they explore cloning.

BRAINPOP© DIRECTIONS: 

1)  Click “Play Movie” to begin the movie. You can click “full screen movie”to watch the movie in a larger screen.

 

2)     Check out the “Q&A” to review important ideas about cloning.

3)     Want to learn some more? Go to “FYI” to learn cool facts about cloning.

4)     How well do you understand cloning?  Take the “Review Quiz” to find out. This is not an assessment – just practice!  Your score is not recorded. 

 

5)     Close the window and return here to learn more!

 



 

As technology and medicine have advanced, the field of biomedical ethics has come to the forefront with many controversial topics, such as the rationing of health services, euthanasia and the definition of death, and reproductive technology. The purpose of this section is just to bring to light some of the questions raised by these advances, not to suggest answers to these questions.
 
Rationing Health Services
 In terms of health and healthcare there are a great number of inequities. Some people are rarely ever sick, while others need constant care just to survive. With a limited number of doctors is it fair to allow a few patients to take so much of their time, even if they will never get better? Is it fair that people with more money and better insurance go to better hospitals and see better doctors? What about organs? Is it fair for a recovered alcoholic to get a new liver to replace the one they destroyed while a child dies for lack of one? These questions have no easy answers, which is one reason health care law is so difficult to write. However, these issues impact people and society as a whole on a daily basis, from the uninsured waiting hours to be seen in a hospital to patients dieing due to lack of availability of organs for transplant. 
 
 
Who Decides What is Death?
Another tough topic is death, and what is clinically dead. With today's advanced medical technology, life can be sustained in a body long after brain activity has stopped. Does that person's family have the right to sustain that life? Sometimes people return from comas long after their family has been told brain death has occurred. Does science have any right to say what defines death in a still living body?
 
Euthanasia (meaning "good death") is on the other end of the spectrum. While many people support the right for a person to choose when to end their life, particularly when diagnosed with a terminal disease, this practice can lead to a slippery slope. If it is alright to assist the terminally ill with their deaths, what about the chronically ill, or the severely handicapped? There are people that believe that those not born "perfect" should not have been born at all. Some people believe that allowing euthanasia could cheapen the sanctity of life, and where does that leave society?
 
 
Reproduction
There is also the opposite problem--the argument over when life begins--brought about by the issue of abortion. A closely related issue is stem cell research. Stem cells have the possibility of curing so many diseases, but gathering stem cells currently requires the death of an embryo. Does the benefit outweigh the cost?
 
Click HERE for a video about the benefits and difficulties of stem cell research.
 
Another issue surrounding reproductive technology is genetic selection. It may soon be commonplace to be asked what gender you'd prefer for your child and what color hair you want them to have. However, genetic diseases could also be all but eradicated. Even now though, genetic screening brings up some issues. Who decides what disease are bad enough for a fetus to not get to be born?
 
Click HERE for an interactive with more information about genetic selection.
 
 
Cloning
In 1996 the cloning of Dolly the sheep sparked a wildfire of debate on the ethics of cloning. While cloning has been used for years in agriculture, the idea of cloning animals and maybe eventually people has many concerned. Cloning organs so that more are available for transplants would be a huge benefit, but losing the diversity of life by cloning whole organisms could cause evolutionary problems. 
 
 

Click here to join Tim & Moby at BrainPop© as they explore cloning.

BRAINPOP© DIRECTIONS: 

1)  Click “Play Movie” to begin the movie. You can click “full screen movie”to watch the movie in a larger screen.

 

2)     Check out the “Q&A” to review important ideas about cloning.

3)     Want to learn some more? Go to “FYI” to learn cool facts about cloning.

4)     How well do you understand cloning?  Take the “Review Quiz” to find out. This is not an assessment – just practice!  Your score is not recorded. 

 

5)     Close the window and return here to learn more!

 



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