Smell Lab – Receptors in Action HASPI Medical Chemistry Lab Background/Introduction A doctor will prescribe specific medications for each sickness a patient might have. In the body, each medication acts differently based on its chemical structure, as it interacts with specific receptors that will result in physiological changes to help you the patient fight whatever they have. Lets take a look at a few different structures. The first medication is aspirin. Aspirin is a pain reliever, also known as an analgesic medicine. The next medication is methylsalicylate. You might see that it is very similar to aspirin, however, methylsalicylate is an antibacterial substance that you will find in your mouthwash. The third molecule looks completely different. This molecule is loratadine, also known as Claritin. Loratadine is an antihistamine molecule. The last molecule is diphenhydramine, also known as Benadryl, another antihistamine. The shape of each molecule is specific to the receptor it will find in the body. A receptor is any place in the body where a drug can selectively bind. A medication is taken to help with a specific problem, so once the bloodstream is full of the medication it bounces around the body until it meets with a receptor it will fit in. We design medications to fit in receptors that control certain responses in the body. Usually, the part of the medication that will fit in the receptor looks a lot like the molecule that normally fits in the receptor. Pain medications fit in our pain receptors. Antihistamines are able to reduce our body’s immune response against common allergens by binding to block the histamines from binding. Heart medications are designed to interact only with receptors in certain parts of our hearts. A receptor is almost like a lock, and the medication fits in the lock like a key. Smell Lab –Receptors in Action , HASPI Medical Chemistry Lab Name(s): Period: Date: Aspirin Methylsalicylate Loratadine Diphenhydramine http://www.adcock.co.za/images/ histamine.jpg O OH O CH3 O O O OH CH3 v s . Page 1
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Smell Lab – Receptors in ActionHASPI Medical Chemistry Lab Background/IntroductionA doctor will prescribe specific medications for each sickness a patient might have. In the body, each medication acts differently based on its chemical structure, as it interacts with specific receptors that will result in physiological changes to help you the patient fight whatever they have. Lets take a look at a few different structures.
The first medication is aspirin. Aspirin is a pain reliever, also known as an analgesic medicine. The next medication is methylsalicylate. You might see that it is very similar to aspirin, however, methylsalicylate is an antibacterial substance that you will find in your mouthwash. The third molecule looks completely different. This molecule is loratadine, also known as Claritin. Loratadine is an antihistamine molecule. The last molecule is diphenhydramine, also known as Benadryl, another antihistamine.
The shape of each molecule is specific to the receptor it will find in the body. A receptor is any place in the body where a drug can selectively bind. A medication is taken to help with a specific problem, so once the bloodstream is full of the medication it bounces around the body until it meets with a receptor it will fit in.
We design medications to fit in receptors that control certain responses in the body. Usually, the part of the medication that will fit in the receptor looks a lot like the molecule that normally fits in the receptor. Pain medications fit in our pain receptors. Antihistamines are able to reduce our body’s immune response against common allergens by binding to block the histamines from binding. Heart medications are designed to interact only with receptors in certain parts of our hearts. A receptor is almost like a lock, and the medication fits in the lock like a key.
When a receptor is activated there are different responses that can occur. Some medications then turn on the receptor and start a physiological response by sending a signal to the brain. Some medications sit in the receptor and block other molecules from starting a response. In some cases, the medicine binds to a receptor in an enzyme or other protein, causing it to change its shape and activity.
Sometimes a medication will fit in other receptors in addition to the target. This causes side effects. Sometimes a new medication might work really well, but because of side effects we will never find it in the stores because it will not pass approval by the FDA. Some medicines are still used despite the side effects because they are so effective at what they do. If you have ever had a strong allergic reaction you might have taken a Benadryl, known generically as diphenhydramine. Benadryl not only works on your skin cells to help with a rash, but it is a molecule that can pass through what is called the blood brain barrier and interact with receptors in the brain. Ultimately, this causes you to become very drowsy. Medicines that make us drowsy can be very dangerous, and can limit your ability to take them. You cannot drive a car if you are too drowsy, and you might have a hard time getting any work done.
Smell Lab –Receptors in Action , HASPI Medical Chemistry Lab
Scientists looked at the diphenhydramine molecule and began to design other molecules that look similar to diphenhydramine but cannot cross the blood brain barrier. This lead to a second generation of antihistamines like Claritin and Zyrtec. Although these drugs are less effective against allergens, they can be taken daily, so they are a great choice as a preventative daily drug for people who suffer from allergies. If you look at the two drugs you can see that there are some similarities, which allow them both to bind to histamine receptors, but that there are differences that change their side effects.
In some cases the different shape of the two molecules can completely change their medicinal qualities. Take a look at the other pair of molecules from the beginning of the lab. You might think they look very similar. In fact, in less than
30 minutes you can do a reaction with just two simple ingredients which will turn Aspirin into Methylsalicylate. This actually changes a lot of the
properties, changing it from a crystal into an oil, and significantly changing the smell so that it is a strong mint smell. These two molecules will no longer fit in the same receptor, which is why they then have different medicinal properties.
Lab ScenarioIn this class we cannot give you a lot of different medications to see what happens, but we can test a group of similarly sized molecules and see how they interact with receptors. Today you will take a look at 15 different molecules that interact with your nasal receptors and help you to smell. Their shape determines which receptors they interact with, causing you to smell different classes of molecules in different ways.
As the molecule interacts with the receptor a signal is sent to the brain. In the brain, the signal is interpreted as a specific smell. This is just like the signals sent when a medication interacts with a receptor within your body.
As you smell each medicine be careful to waft each scent as they can be very overwhelming in some cases.
Pre Lab Questions1. What is a receptor?2. What causes a drug to interact with a receptor?3. What responses may occur if a receptor is activated?4. Analyze the following statement: If two drugs look similar they will have similar effects.
a. Is this always true, sometimes true or never true?b. Explain your answer
5. How are scents similar to medications?6. What can a scientist take into account when designing a drug for a specific receptor?7. What is a cause of side effects?
Smell Lab –Receptors in Action , HASPI Medical Chemistry Lab
Smell Lab – Receptors in ActionHASPI Medical Chemistry Lab
ProcedureIn this lab your goal is to try to identify each smell and note any relationships between molecules with the same functional groups. Follow along as your teacher runs the PowerPoint presentation to better understand what each molecule is made of and how the structure affects the activity of the molecule.
Part A: Aldehydes Molecule Odor 1 Odor 2 Odor 3
Smell Prediction
1. Each of these molecules has a different odor. Explain why:
2. Aldehydes are a family of organic molecules because they all share something in common. In looking at the three molecules in part A and the one shown below, decide what is the unifying pattern that makes all of these molecules aldehydes and draw it in space to the right.
Actual Smell Odor 1 Odor 2 Odor 3
Part B: Esters Molecule Odor 4 Odor 5 Odor 6
Smell Prediction
Smell Lab –Receptors in Action , HASPI Medical Chemistry Lab
Name(s): Period: Date:
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1. The odors 4, 5 and 6, are part of the family of molecules called esters.Try to find the common pattern within the family of esters and draw it on the right
Most organic molecules are largely made of carbon (C) and hydrogen (H) atoms. Because of this, it is often distracting to draw in every carbon and hydrogen atom in a molecular structure. So scientists often draw the organic molecules in a short-hand version where the carbon atoms are inferred by the points of
lines and shapes.
a. How many carbon atoms and hydrogen atoms do you see in the short-hand version of Odor 4?
C=
H=
b. How many carbon atoms and hydrogen atoms do you see in the full atom version of odor 4?c. Compare the 2 versions of Odor 4. What does the number 3 on the H3 represent?d. Oxygen atoms are shown in both versions. How many oxygen atoms are in Odor 4?
Compare the 2 versions of Odor 5 shown below and answer the related questions on the right
a. Using the full atom version, circle the parts that are also visible in the shorthand version
b. Using the shorthand version, fill in the missing atoms that are shown on the full atom version.
Describe and illustrate how carbon atoms are represented in the shorthand version
Take a look at odor 6. Circle all the unwritten carbon atoms.
How many carbon atoms are in odor 6?
Actual Smell Odor 4 Odor 5 Odor 6
.
Smell Lab –Receptors in Action , HASPI Medical Chemistry LabPage 4
Part C: Terpenes Molecule Odor 7 Odor 8 Odor 9
Smell Prediction
1. The odors 7, 8 & 9 comprise the family of molecules called terpenes. Identify the common pattern within the family of terpenes and draw it on the right.2. Compare odor 7 & 8. Explain why they might have similar smells.There are a lot of different ways to put together a set of atoms. Two compounds with the same molecular formula (all of the same atoms), but with different structures are called isomers. Odor 7 and Odor 8 are sterioisomers, meaning they are put together the same, but in this situation they are mirror images of each other. Just like your right hand and left hand fit only in the glove that was made for that hand, these sterioisomers react with your olfactory receptors differently.Can you find all 10 of the carbon atoms in Odor 7 and Odor 9 ? Three of them are easy to find, but can you find the other seven which are the not drawn in on the short-hand version. Circle all 10 carbon atoms for each molecule.
Actual Smell Odor 7 Odor 8 Odor 9
Part D: AlcoholsMolecule Odor 10 Odor 11 Odor 12
Smell Prediction
1. The odors 10, 11 & 12 comprise the family of molecules called alcohols. Identify the common pattern within the family of alcohols and draw it to the right.
Smell Lab –Receptors in Action , HASPI Medical Chemistry LabPage 5
2. The short-hand and full atom version of Odor 10 is shown. Answer the following questions relating to the structures
a. Refer to the full atom version for Odor 10. How many lines are connected to each carbon atom?b. How many lines are connected to each hydrogen atom?c. How many lines are connected to each Hydrogen atom?
3. Molecular Structures would not exist without the valence electrons that are available for bonding. Draw the lewis dot structures for carbon, hydrogen and oxygen
C H O
4. How are unpaired electrons in a lewis dot structure similar to the lines that are shown to connect 2 atoms in a molecular structure?
5. The atoms that comprise the molecular structures in this lab are carbon, hydrogen and oxygen atoms. They are all non-metals. What type of bond holds the atoms together?6. Shown to the right are two short-hand versions of Odor 10, the one on the right includes all of the hydrogen atoms. Look at the arrows pointing at two different carbon atoms in the representation on the left. Observe in the representation on the right that each of those carbon atoms has a different amount of hydrogen atoms bonded to it. Look for a pattern and provide a reason why you think this happens?
Actual Smell Odor 10 Odor 11 Odor 12
Part E: Ketones Molecule Odor 13 Odor 14 Odor 15
Smell Prediction
1. The odors 13, 14 & 15 comprise the family of Smell Lab –Receptors in Action , HASPI Medical Chemistry LabPage 6
molecules called ketones. Identify the common pattern within the family of ketones and draw it to the right.2. Circle all of the carbon atoms in Odor 13. How many carbon atoms does it have?
How many oxygen atoms does it have?
How many hydrogen atoms does it have?
What is the formula for odor 13?
3. Draw the full atom version of odor 13 in the space to the right. Refer back to your previous work for help.4. Look at odor 14 and determine how many carbon atoms need hydrogen atoms and draw them in on the structure on the right.
Actual Smell Smell 13 Smell 14 Smell 15
Post Lab QuestionsLook at this molecule of caffeine How many carbon
atoms are in caffeine?How many oxygen atoms are in caffeine?How many hydrogen atoms are in caffeine?What is the formula for caffeine?
Draw the Lewis Dot Structure for N and SN S
How many bonds would you expect each atom to form?
