Macromolecule modeling lab

Transcription

1 Macromolecule modeling lab Goal: Use ball and stick models to build some of the macromolecules that make up cells also see how complex and large these macromolecules can be Directions to read before starting: 1) Open the black box and look at the key inside the box top. Make sure you know which color corresponds with which atom. Carbon = C ydrogen = Oxygen = O Nitrogen = N 2) Lines between atoms in the drawings below represent chemical bonds. --a single line is a single bond --You ll use the short sticks for single bonds --a double line is a double bond --You ll use the long bendy sticks for double bonds Carbohydrates Question 1: Discuss the basic function of carbohydrates as a group. Athletes are often advised to eat a meal rich in carbohydrates the night before an athletic event why? What do you eat? We will start with one of the simplest carbohydrates, glucose. Start by building a ring as indicated below: Note that I have numbered the different carbons this will help us later when we put together glucose biomoleules as a class to make a big carbohydrate. Keep going, you re not done yet (see next page)

2 Now attach the other groups to each carbon you shouldn t have any unfilled holes in your atoms. Your completed glucose will look like this: Count all of your atoms and you should come up with the chemical formula for glucose = C612O6 why is glucose so important? 2 reasons: reason #1) Our body might immediately burn glucose to produce energy for the cell, a process that is called cellular respiration we will study the chemical formula below in chapter 9. C 6 12 O O 2 6 CO O + energy reason #2) If our cells DON T need energy right away, they store it by joining glucose molecules together in a long chain. Plant cells make long chains of sugars called starch (that s why you eat pasta), and animal cells make long chains of sugars called glycogen. Your body has the ability to break down starch or glycogen for energy that s why you can eat plants and animals for a source of food energy.

3 Now it s your turn to start putting glucose molecules together. Find another group who has built a complete glucose molecule and read this far: Below, I ve removed the unimportant and O groups to keep things simple. In order to combine the glucose biomolecules, you will use one of the oxygen atoms as a bridge between C1 of one glucose molecule, and C4 of the other. In order to do this, you have to remove the from the bridge O, and also remove the O and from the other carbon. Your finished product should look something like this. Question 2: Look carefully at the atoms you removed what common molecule did you remove in order to put 2 glucose molecules together?

4 Maybe you are wondering if you can connect a third glucose molecule to your group. Absolutely using the same technique illustrated again below: This is no different from the first combination. ow many glucose molecules can you put together as a class? Cells that make starch or glycogen molecules put together thousands of glucose molecules truly a big biomolecule. Also note that this process is reversible cells can use water to split large macromolecules into smaller glucose molecules. This is called hydrolysis (literally, water splitting ). Lipids = Fats Question 3: Discuss with your group about the basic function of fats in a cell. In order to construct a giant lipid, we will be splitting the responsibilities into groups and then working together at the end. I will assign 1/4 of the groups to build the connector molecule, which is called glycerol:

5 The other 3/4 of groups will build the fatty acid chains that will eventually connect to the glycerol. Recall the directions on the first page about how make a double bond with springs. The fatty acid chain on the last page only has a few C groups (seven on our molecule) but fatty acid chains have hundreds of C groups attached. One glycerol group needs to get together with 3 fatty acid chain groups (or 2 fatty acid groups if there are not enough fatty acid groups) The picture below shows how one fatty acid chain connects to the glycerol (hopefully the process looks familiar): ere is the end result, and the next fatty acid chain connecting: Question 4: Again, each time you connect two molecules, what common molecule comes off? Connect the third fatty acid and you have a giant lipid.

6 Extra information: Oil and water don t mix. Why does this happen? After all, I thought water could dissolve anything! Well, water can dissolve anything that is polar, or molecules with a full or partial charge. But oil has very nonpolar, uncharged C groups. Nonpolar and polar substances will not mix with each other. This will be important once we discuss the cell membrane (which has nonpolar and polar parts). Proteins δ+ O δ- water (polar) δ+ Na + - C Question 5: Discuss with your group the function of proteins in a cell. Also identify the basic unit that link together to build large proteins. Build one amino acid in your group, then link them together to make a class protein. There are 20 different amino acids that can be linked together. A general amino acid looks like: Cl sodium chloride salt (very polar, dissolves in water) hydrocarbon (nonpolar, does not dissolve in water) All amino acids have a central carbon with an, and N2, and COO group around it. The circled R group is the part that is unique for every amino acid. For example, here are some sample amino acids (you don t have to build these): The amino acid serine The amino acid phenylalanine

7 Go ahead and build the generic amino acid. You can use a green, orange, or purple ball to represent the generic R group of any amino acid. When other groups are finished, you can start to put together your amino acids and make a protein. See the picture below for help basically you will connect the N of one amino acid to the COO carbon of another amino acid. The completed product should look like: Question 6: Again, what molecule comes off when putting together smaller molecules? And of course you can add a third amino acid and a fourth how many can you link together?

8 Nucleic Acids Nucleic acids are a little too complicated for us to build. So go ahead and dismantle your models now and place all the wooden spheres, sticks, and springs back in the kit box (in the right place! black carbons and blue nitrogens go on one side, all other colors into the main box). Question 7: Discuss the function of nucleic acids as a group. Just like carbohydrates (glucose) and proteins (amino acids), you should know the base unit for nucleic acids as well. We put together to build a nucleic acid. Phosphate group Nitrogenous base Ribose sugar The picture above shows one nucleotide which are combined to make nucleic acids. Look at all the different atoms that make up a nucleotide a very diverse molecule. You might be more familiar with the letters of the genetic code A, T, C, and G. Each letter is one of the nitrogenous bases above within a nucleotide. We just represent it as a letter for simplicity. There are thousands and thousands of these letters in one strand of DNA, so there must be a way for nucleotides to combine. The O of the nucleotide at the top will form a new bond with the P of the nucleotide below. In the process the O and in boxes will leave as water (again).