Unit 2
CHEMISTRY—RAW MATERIALS AND FUEL
FOR OUR BODIES
Learning Objectives
• Relate major principles of chemistry to the study of biology
• Understand atomic structure
• Compare and contrast the major chemical bonds involved in important molecules and compounds
• Identify the major macromolecules that make up living organisms
• Explain the importance of the function of each of the four major macromolecules
• Describe the different categories of carbohydrates and their uses
• Compare and contrast different categories of lipids and their structures
• Understand the importance of shape in the functioning of a protein.
• Compare and contrast DNA and RNA
Chapter Outline
I. Atoms Form Molecules through Bonding
• Understanding chemistry is essential to the study of biology. Learning about chemistry allows us to understand the
necessary building blocks of important molecules and the chemical reactions that help power a cell.
• Long regarded as precious, gold has always been evaluated for its beauty and value. However, when evaluating gold
for its chemical makeup, gold is an example of an ____________________________ or a substance that cannot be
broken down further into any other substance.
A. Atomic Structure
• Describe the relationship between an atom and an element.
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12 Chapter 2. Chemistry: Raw Materials and Fuel for Our Bodies
• The individual particles, or pieces, that form the structure of an atom have unique characteristics. Complete the
following chart to highlight the particles that form the structure of an atom.
o Which two particles make up the nucleus of the atom?
• Define the atomic mass of an atom.
o Do electrons contribute to the overall mass of the atom? Explain.
• Carbon has an atomic number of six. This number refers to the number of _________________ carbon has. Will any
other atom of a different element have the same number? Explain.
• There are many different naturally occurring elements. When examining the human body we find we are composed of
25 different elements. Of those 25, only four elements make up approximately 96% of us! List the “Big 4” here.
1.
2.
3.
4.
B. Atoms’ Electron Shells
• __________________________determines how and if an atom will bond with other atoms.
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• Because the aforementioned particle carries a negative charge, there is a limit to the number that move around the
nucleus of the atom together, or in the same electron shell.
o The atom’s first electron shell, which is innermost and closest to the
nucleus, can hold __________________________electrons.
o The second and subsequent shells can hold more, or up to _____________ electrons.
• Draw the appropriate number of electron shells and the appropriate number of electrons in each shell for carbon. The
nucleus of the atom is below. (Hint: Carbon has six electrons.)
• Explain why the atom is stable when the outermost electron shell is full.
o What happens if the outermost shell is empty?
• In your own words, briefly describe what an atom has to do to become an ion.
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C. Chemical Bonding
• A molecule is a group of ____________________________held together by _______________________.
• What determines the type of bond that will form between reactive atoms?
• Types of bonds—Describe how each bond holds atoms or groups of atoms together and
list an example.
1. Covalent bond:
2. Ionic bond:
3. Hydrogen bond:
D. Consequences of a Molecule’s Shape
• What determines the shape of a molecule? Use an example.
• What two important senses are impacted by the variation in shape of different molecules? Explain why.
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II. Water Has Features That Enable It to Support All Life
A. Water Molecule Properties and the Hydrogen Bond
Explain, using the term polar molecules, how organisms such as the Jesus Lizard can take advantage of surface tension
and walk across water.
B. Properties of Water Make it Critical to Life
• List the four important properties of water and then explain how the feature is essential for living organisms.
1.
2.
3.
4.
C. Acids, Bases, and pH
• A water molecule can be broken apart releasing _____________ and _____________ ions.
• These ions individually can affect the pH of a particular solution. The pH scale measures:
• A fluid with a pH between 0 and 6.9 would be considered __________________ and has more H or OH ions?
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• A fluid with a pH between 7.1 and 14 would be considered ________________ and has more H or OW ions?
• Give your own example of a food or household item that would register as an acid on the pH scale. Give an example of
an item that would register as basic.
• Explain what happens to a solution when you add a buffer.
III. Carbohydrates are Fuel for Living Machines
• A macromolecule can be simply defined as:
• The four major types of macromolecules that are necessary for our cells include:
1.
2.
3.
4. Carbohydrates
a. Carbohydrates are made up of the three following elements:
1.
11.
111.
b. All carbohydrates are found with a similar composition of an H20 unit for every carbon. Give the chemical formula for
glucose: __________________
c. What is the primary function of carbohydrates in our cells?
i.
Explain why carbohydrates are so well-suited for this function.
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A. Monosaccharides
• Monosaccharides are also called __________________. Give an example of a monosaccharide with which you are
familiar with.
• The glucose from fruit, bread, potatoes and other carbohydrate sources ends up in the bloodstream. There are then
several potential end results for the glucose circulating in the blood. Explain the three potential fates.
• What is glycogen’s role in “carbo-loading”?
• What does “water weight” have to do with glycogen?
B. Complex Carbohydrates
• Complex carbohydrates are a source of fuel containing more than one sugar building block. These include:
1. _______________________ which are two monosaccharides linked together and,
2. _________________________which are many monosaccharides (even thousands) linked together.
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• Disaccharides
o Give an example of a disaccharide and explain how it is utilized for fuel.
• Polysaccharides
o What is the function of starch in plants?
o What is the function of glycogen in humans?
• There are unique polysaccharides that are indigestible by humans but can serve as structural material for various
organisms. Give an example of where each of the following are found.
o Chitin:
o Cellulose:
Why is cellulose an important part of the human diet even though humans cannot digest it?
IV. Lipids Store Energy for a Rainy Day
• Lipids are a large, diverse group of macromolecules with important functions. Like other macromolecules, the
structure of lipids includes the elements C, 0, and H, but lipids have a higher ratio of C-H bonds. How does this affect
lipids?
• Some important properties of lipids include how they behave in water. Define:
o Hydrophobic:
o Hydrophillic:
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• List the three types of lipids and their function.
1.
2.
3.
A. Fats
• The fats we are concerned about in the foods we eat are also called: _________________________________________
• List the parts of the structure of a triglyceride and label these parts on the symbol below.
• Explain the structural difference between a saturated fat and an unsaturated fat.
o What is a favorite food of yours that is high in saturated fats?
o What is a favorite food of yours that is high in unsaturated fats?
• How is trans fat different from both saturated and unsaturated fats?
• Olestra is a fat substitute. It is found in many food products, such as potato chips, that strive to reduce the fat content
in order to make the product more appealing to consumers.
o What is the chemical structure of olestra?
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20 Chapter 2. Chemistry: Raw Materials and Fuel for Our Bodies
o Are there consequences associated with a diet high in olestra? Explain.
B. Sterols
• What is the basic structure of all sterols?
• List two important examples.
C. Phospholipids
• Draw the basic structure of a phospholipid.
• This category of lipids plays an important role in the cell’s ___________________
V. Proteins are Body-Building Molecules
• Proteins are the most diverse groups of macromolecules and function to regulate cellular activity, provide support, and
assist in chemical reactions.
A. Protein Structure
• Proteins are similar to carbohydrates and lipids as they also contain C, 0, and H, but they can be distinguished from
these other important macromolecules because they also contain ______
• Despite the large variety of proteins found, they are all composed of the same building blocks. By connecting different
_____________________ together, the result is a unique protein. There are ______ different amino acids available, just
as there are 26 letters in our alphabet to select from when writing different words.
• Structure of an amino acid
o Identify the three main groups that form the structure of the amino acid.
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o What makes one amino acid different from another?
B. Protein in Your Diet
• Our cells require amino acids for various cellular structures and activities. Cells can make some of the amino acids that
are required, but not all of them. Other necessary amino acids are obtained through the diet. The amino acids we must
be certain to include in our diet are called ________________________________________
• Briefly describe the difference between a complete protein and an incomplete protein.
C. Protein Shape
• Cells will build protein by linking amino acids together by a __________________ bond.
• The order of the amino acids as well as the overall structure the protein takes on impacts how that protein functions.
o The possible shapes, or structure, of proteins are:
1.
2.
3.
4.
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o If at any time, something alters the shape of the protein, the protein will no longer be able to function
properly. That, in turn, can affect cellular functioning.
• When a protein is exposed to an extreme environment, such as high temperature or changes in pH, what is the term
that is used to describe what has occurred?
o Explain why we call the clear or opaque protein of an egg, an egg “white.”
D. Enzymes
• One important class of proteins is enzymes. Briefly explain what an enzyme’s job is and if they can perform their job
more than once.
o Only specific substrates can fit in an enzyme’s _______________ site to catalyze a reaction.
o Explain why disease or disorder could result from an enzyme that isn’t formed properly. Include an example.
VI. Nucleic Acids Store the Information on How to Build and Run a Body
• The fourth major category of important macromolecules is nucleic acids. Two types of nucleic acids are:
1.
2.
• The building blocks for nucleic acids are
• A nucleotide is made up of three parts:
1. A phosphate group (P04)
2. A sugar
3. A nitrogen containing molecule called a ________________________________
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o Each nucleotide can contain one of different bases. These bases include:
1.
2.
3.
4.
A. DNA
• Briefly explain the job of DNA in producing proteins.
• Many nucleotides link together create a strand of DNA. One strand of DNA is bound to a second strand of DNA by
____________________ bonds. These two strands then spiral around each other forming the structure of DNA known as
A _________________________.
• It is often easier to draw DNA as if it were a ladder. The vertical uprights of the ladder would include the
_____________________________ and _______________________________ The rungs of the ladder, or where you
would place your foot if you were climbing the ladder, would be the ___________________
• If you were to examine the structure of DNA in great detail you would start to notice a pattern in which DNA bases
were connected, or how one strand of DNA was bound to the second strand of DNA. Explain which bases always pair
together.
B. RNA
• Briefly explain the job of RNA in producing proteins.
• There are three major differences between DNA and RNA. List the ways RNA is unique:
1.
2.
3.
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Testing and Applying Your Understanding
Multiple Choice (For more multiple choice questions, visit www.prep-u.com.)
1. Which of the following statements about enzymes is NOT true?
a) Enzymes speed up chemical reactions.
b) Enzymes reduce the energy difference between reactants and products.
c) Enzymes are biological catalysts.
d) Enzymes often induce conformational changes in the substrates to which they bind.
e) Enzymes lower the activation energy of chemical reactions.
2. One of the four nucleotide bases in DNA is replaced by a different base in RNA. Which
base is it, and what is it replaced by?
a) Adenine, replaced by uracil
b) Thymine, replaced by guanine
c) Guanine, replaced by cytosine
d) Thymine, replaced by uracil
e) Cytosine, replaced by guanine
3. Which statement about phospholipids is FALSE?
a) They are hydrophilic at one end.
b) Because their phosphate groups repel each other, they are used as organisms’ chief form of short-term energy.
c) They are a major constituent of cell membranes.
d) They contain glycerol linked to fatty acids.
e) They are hydrophobic on one end.
4. Evaporation from the leaves of a tree will pull water up through the roots as an unbroken column throughout the
entire height of the tree. This feat is possible because of which characteristic of water?
a) Cohesion
b) Kinetic energy
c) Surface tension
d) Absorption
e) Vaporization
5. The thing that distinguishes one element, such as chlorine, from another such as neon, is:
a) the number of protons and neutrons in the nucleus.
b) the number of protons in the nucleus.
c) the number of neutrons in the nucleus.
d) the number of electrons.
e) the number of protons, neutrons, and electrons.
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6. One important difference between covalent and ionic bonds is that:
a) in covalent bonds two atoms share electrons, whereas in ionic bonds one atom gives one or more electrons to the
other atom.
b) ionic bonds only occur among water-soluble elements.
c) in ionic bonds two atoms share electrons, whereas in covalent bonds one atom gives one or more electrons to the
other atom.
d) ionic bonds are much stronger than covalent bonds.
e) in ionic bonds both protons and electrons can be shared, whereas in covalent bonds only electrons can be shared.
7. Which of the following is a polysaccharide?
a) Cellulose, the primary component of plant cell walls
b) Glucose, the chief cellular energy source
c) Insulin, the chief blood sugar regulator
d) Fructose, one of the most important blood sugars
e) All of the above are polysaccharides.
8. Saturated fatty acids have __________________ than unsaturated fatty acids, which is why
they exist as a ______________ at room temperature.
a) fewer hydrogen atoms; solid
b) more carbon atoms; solid
c) more double bonds; liquid
d) fewer double bonds; solid
e) more glycerol molecules; liquid
9. When you put a piece of chocolate on your tongue, your brain registers a sensation of
sweetness. What aspect of molecules is responsible for their having a particular taste?
a) the total number of protons in the molecule
b) the amount of hydrogen bonds in the molecule (more hydrogen bonds = sweeter taste)
c) the molecule’s shape
d) the ratio of covalent bonds to ionic bonds joining the atoms of the molecule
e) the total number of electron shells in the atoms of the molecule
10. Proteins are an essential component of a healthy diet for humans (and other animals).
Their most common purpose is to serve as:
a) inorganic precursors for enzyme construction.
b) fuel for running the body.
c) raw material for growth.
d) long-term energy storage.
e) organic precursors for membrane construction.
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Short Answer
1. Using the following example, identify the atomic mass and atomic number of the element. If this was a neutral
atom, how many electrons would it contain? Explain your answer.
2. Explain the difference between a stable atom and an unstable atom.
3. Chlorine atoms have an atomic number of 17. Assuming there are two neutral atoms present, draw the electron
shells of two chlorine atoms and predict the type of bond that will form between them. Explain your answer.
4. Explain the chemical properties that allow water to be a good solvent.
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5. Your roommate is experiencing heartburn and asks you what she should take for some relief. Explain, chemically
speaking, how an antacid will help eliminate her discomfort.
6. We know once glucose arrives in the cell it can be used to fuel cellular activities. Explain why, then, athletes
consume meals high in starches prior to an event versus meals high in simple sugars or fibers.
7. When examining the packages of some snack foods that are made with olestra you note that certain vitamins
are included in the ingredient list but with the notation that they are dietarily insignificant. Why would the
manufacturer be including vitamins in the ingredients of the snack food containing olestra?
8. There are several major categories of hormones in the body that vary based on their monomer units, or building
blocks. A researcher investigating the functionality of hormones heats estrogen, testosterone, and insulin to a
very high temperature. After heating the hormones, the researcher tests to see if they still work properly. She
finds that estrogen and testosterone still function, but insulin does not. Based on the chemical nature of these
molecules, explain why insulin no longer functions.
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