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Biology CP-Mr.Willets
Lab- Molecular Models
Organic molecules are essential to life. Indeed, the name organic comes from the word organism because it was thought originally that only living things could make them.
Organic molecules are composed of a carbon "backbone" to which other atoms (mostly hydrogen, oxygen and nitrogen) are attached. The carbon atoms can join to each other in chains (branched or straight) or rings. These molecules can be quite complicated and it is often easier to study them using models.
The colored balls represent atoms. The black ones are carbon atoms which can form 4 bonds. The balls have four holes in them for this purpose. The red balls are oxygen (2 bonds), the blue are
nitrogen (3 bonds) and the yellow are hydrogen (one bond). You should remember the number of bonds each atom has for the next test. (C-4 N-3 O-2 H-1)
These balls (atoms) are joined with pieces of wood. There are two lengths. Use the longer ones to attach the carbon atoms together. Use the smaller ones to attach the hydrogens and oxygens to the carbons. The springs are used for double bonds. I will show you in class how to use the springs.
Some Simple Molecules-After you make each model, draw its structure in the spaces below
1) Water- H2O Make a model of water. Note its bent shape.
2) Ammonia NH3 Make a model of ammonia.
3) Methane CH4 Make a model of methane. This is natural gas. This is considered to be an organic molecule even though it has only one carbon
4) Ethane C2H6 Make a model of ethane. Join the two carbons together and then add the hydrogens
5) Ethanol C2H5OH Use the ethane model from above. Remove one hydrogen and replace it with an oxygen-hydrogen combination. This makes a molecule called ethanol Does it matter which hydrogen is removed? Try putting the OH in different places to see if you get a different molecule. Another name for ethanol is ethyl alcohol.
Draw the structural formulas for the five molecules you made. Don't use circles, just letters.
Some Complicated Molecules-
1) Glucose -C6H12O6 The six carbons in glucose can be in a chain or in a ring. Make a model of the chain form (see page 43) The carbon atoms are numbered in the diagram to make it easier to keep track of what goes where. When everyone is done, we will twist it into the ring form. Please wait to do this.
2) Fructose -C6H12O6 This has the same molecular formula as glucose but is put together differently. Use the book to make a model of the chain form of fructose. Use your glucose molecule and rearrange the necessary pieces. (Answer question #5 now)
3) Simple Amino AcidMake an amino acid according to the structural formula shown below. CH2NH2COOH You will have to dismantle the fructose. When I have checked it, make another one just like it.
The NH2 part of the molecule is called the amino group
The COOH part is called the acid group
4) DipeptideWhen two amino acids bond, they form a dipeptide. The process is called dehydration synthesis. Use the two amino acids you made to create a dipeptide. Remove an "OH" from the acid group of one amino acid and remove a "H" from the amino group of the other.
Remove these to have a place to join the two amino acids- Put together the H and the OH that you removed What do they form?
Questions-
1) Where does the name "organic" come from?_________________________________________
2) How many bonds can Carbon form? _____ Nitrogen? ________ Oxygen?_______ Hydrogen? ______
3) The backbone of organic molecules is made of what atoms? ________________ In what ways can these be arranged? _________________________________________________________________
4) Methane is unusual for an organic molecule because it has only one ___________
5) One difference between glucose and fructose is where the double -bonded oxygen is located. On which number carbon is this oxygen bonded on glucose? ___________________ On which number carbon is it bonded on the fructose molecule? _____________ Molecules that have the same formula but different structures are called isomers of each other (nice word to know).
6) What general name is given to a molecule formed by joining two amino acids? ___________________
7) The amino acid molecule is made of a central carbon atom to which 2 groups are bonded: On one end is the _____________________group which is made of a _____________atom and 2 _____________atoms
On the other end is the _______________group consisting of a carbon atom with a double bonded ________________ and a ______________________combination. When two amino acids bond, a ___________________ is removed from one of them and a _____________________ combination is removed from the other. These removed pieces join to form_________ What is this overall process called? _________________________________