CHAPTER 5 The Structure and Function of Macromolecules
The Principles of Polymers
READ: Skim Overview and Section 5.1, carefully read “The Synthesis and Breakdown
of Polymers” to answer questions.
1. List the four major classes of macromolecules.
Carbohydrates
Lipids
Proteins
Nucleic Acids
2. Distinguish between monomers and polymers.
Monomer- mono = 1 subunit of a macromolecule
Polymer- poly = many monomers linked together
Monomers are repeating units that serve as the building blocks for a polymer
3. Draw diagrams to illustrate dehydration and hydrolysis reactions. (When is water lost, when is it used?
See figure 5.2
Dehydration- joins monomers together to form polymers, water is lost
Hydrolysis- breaks polymers apart into monomers, water is used
Carbohydrates Serve as Fuel and Building Material
READ: Skim Section 5.2 and carefully read text relating to Figures 5.5 and 5.7 to answer
Questions.
4. Distinguish between monosaccharides, disaccharides, and polysaccharides.
Monosaccharide = monomer of the carbohydrate macromolecule
Disaccharide = 2 monomers linked together by a dehydration reaction
Polysaccharide = 3 or more monomers linked together by dehydration reactions
5. Describe the formation of a glycosidic linkage.
This is the covalent bond that forms between carbohydrate monomers linked together in a
dehydration reaction.
Also be able to….Identify the monomer of carbohydrates and the bond that links these monomers.
Monomer: monosaccharide
Bond: glycosidic
6. Distinguish between the glycosidic linkages found in starch and cellulose. Explain why
the difference is biologically important.
Starch- ALPHA glucose monomers are linked by glycosidic bonds. Your body CAN
break the glycosidic linkages between these ALPHA glucose monomers.
Cellulose- BETA glucose monomers are linked by glycosidic bonds. Your body
CANNOT break the glycosidic linkages between these BETA glucose monomers.
This question put another way ….
Starch, like what you would find on the INSIDE of a baked potato, and Cellulose, what
you would find in the potato’s skin, are both made of glucose monomers. What type of
glucose monomer would you find in starch and what type of glucose monomer would you
find in the cellulose?
Distinguish between the glycosidic linkages found between alpha glucose monomers and
those between beta glucose monomers. Explain why the difference is biologically
important.
Starch- ALPHA glucose monomers are linked by glycosidic bonds. Your body CAN
break the glycosidic linkages between these ALPHA glucose monomers. If your body
can break the linkage between the glucose monomers, you can absorb the glucose from
the digestive tract and use it as an energy source.
Cellulose- BETA glucose monomers are linked by glycosidic bonds. Your body
CANNOT break the glycosidic linkages between these BETA glucose monomers. If your
body cannot break the linkage between the glucose monomers, you cannot absorb the
glucose from the digestive tract and cannot use it as an energy source.
7. Describe the role of symbiosis in cellulose digestion.
Some animals, such as cows, have organisms in their intestines that CAN break the glycosidic
linkages between BETA glucose monomers. Therefore the cow indirectly has the ability to break
these beta linkages and use the beta glucose monomers to produce ATP. The organisms in the
cow’s intestines also benefit, as they get a great place to live and food that the cow ingests.
Lipids are a Diverse Group of Hydrophobic Molecules
READ: Skim Section 5.3 and carefully read text relating to Figures 5.11, 5.12 and 5.13
to answer questions
8. Describe the building-block molecules, structure, and biological importance of fats,
phospholipids, and steroids.
This question put another way….
Compare and contrast the 3 major categories of LIPIDS: fat, phospholipids, and steroids
by describing the:
-building-block molecules (monomers)
-structure
-biological importance
Fat: Triglyceride
Building-block moleculesMonomers- glycerol and fatty acids
Structure –
3 fatty acids linked to one glycerol
Biological importanceEnergy source
Phospholipids:
Building-block moleculesMonomers- glycerol, fatty acids and a phosphate group
Structure –
2 fatty acids and one phosphate group are linked to one glycerol molecule.
The phosphate group is polar and the fatty acids part of the phospholipids is nonpolar. The
Biological importance- Phospholipids are a major component of cell membranes and form
a bilayer. The polar “head” is positioned toward the outside and inside of the cell, which
has an affinity for the aqueous environment found both outside and inside the cell. The
fatty acid tails of each layer of phospholipids are positioned toward the center of the
membrane due to their nonpolar (water hating) nature.
Steroids:
Building-block molecules/structure4 carbon ring structure with various carbon side chains and functional groups linked to that
4 carbon ring structure.
Biological importance- Several hormones are steroids, including estrogen and testosterone.
9. Identify an ester linkage and describe how it is formed.
Just be able to identify what macromolecule’s (lipids) monomers are linked by ester bonds. The ester l
forms by a dehydration reaction among the lipid monomers.
Identify the linkage between the monomers of Lipids and describe how it is formed.
Ester bonds. The ester linkage forms by a dehydration reaction among the lipid monomers.
10. Distinguish between saturated and unsaturated fats.
Saturated = carbon skeleton is saturated with hydrogen atoms, NO double bonds so there is a
very close association among lipid molecules. This is why saturated fats are solid at room
temperature
Unsaturated = carbon skeleton is NOT saturated with hydrogen atoms; double bonds are present
in these molecules so there is not a very close association among these lipid molecules. This is
why unsaturated fats are liquid at room temperature
11. Name the principal energy storage molecules of plants and animals.
triglycerides
Proteins have Many Structures and Many Functions
READ: Skim Section 5.4 and carefully read text relating to Figures 5. 17, 5.18, 5.21
to answer questions
12. Distinguish between a protein and a polypeptide.
Polypeptide- a chain of amino acids linked by peptide bonds
Protein- a polypeptide chain or several polypeptide chains folded into the correct conformation
also be able to…
A. Identify the monomer of protein and the bond that links these monomers.
B. Distinguish between a protein and a polypeptide.
A. Monomer: amino acids, Bond: peptide bond
B. Polypeptide- a chain of amino acids linked by peptide bonds
Protein- a polypeptide chain or several polypeptide chains folded into the correct conformation
13. Explain how a peptide bond forms between two amino acids.
Dehydration reaction: The amino group of one amino acid monomer is linked through
dehydration to the carboxyl group of another amino acid monomer.
14A. List and describe the four major components of an amino acid. Explain how amino acids
may be grouped according to the physical and chemical properties of the R group.
Major components:
1. amino group
2. carboxyl group
3. R group (can be polar, nonpolar, electrically charged)
3 Rules for determining whether an amino acid is nonpolar, polar or electrically charged:
1. Does the R group have only carbon (C) and Hydrogen (H)? If yes, it is NONPOLAR! If
no, move on to question 2.
2. Is the atom that is not C or H on the end of the R group or surrounded by carbon and
hydrogen? If the atom that is not C or H is surrounded by C and H, the R group is
NONPOLAR. If the atom that is not C or H is NOT surrounded by C and H, move on to
question 3.
3. Is there a charge negative (-) or positive (+) on the atom that is not C or H? If no, then
the R group is POLAR. If yes, then the R group is ELECTRICALLY CHARGED.
14B. The R group of the amino acid Serine is –CH2-OH. The R group of the amino acid Alanine
is –CH3. Where would you expect to find these amino acids in a folded protein that is in
and aqueous (water) solution? (HINT: Think of the 3 categories of amino acid side chains,
how are Serine and Alanine categorized? How would this affect where they would be found
in the protein?)
Alanine would be in the interior and Serine would be on the outside of the protein. Alanine is a
nonpolar amino acid, so it is also hydrophobic, water hating, It would hide from the water
enviroment of a living thing by tucking itself inside the protein. Serine is a polar amino acid, so it is hy
water loving. It likes substances that are like itself and would be just fine exposed to the water environ
living thing and would be on the outside of the protein.
15. Explain what determines protein conformation and why it is important.
Protein conformation (3-D structure) is in large part determined by hydrogen bonding among
both the amino acid backbones of each amino acid in a polypeptide chain and between R groups.
Other types of bonding occur between R groups that also contribute to the 3-D structure such as
ionic bonding and disulfide bridges
The 3-D structure is important because the structure of the protein determines its function. If the
structure is lost the protein will not function.
16. Explain how the primary structure of a protein is determined.
The order of the amino acids (primary structure) in a polypeptide chain is determined by the DNA
sequence.
17. Name two types of secondary protein structure. Explain the role of hydrogen bonds in
maintaining secondary structure.
Alpha helices and beta-pleated sheet, result from hydrogen bonds between the backbones
of amino acids in the polypeptide chain. The backbone of an amino acid includes the parts
of the amino acid that is the same in every amino acid, the amino group the carboxyl group
the hydrogen atom, everything EXCEPT the R group!!!
18. Bonds between which part of the amino acids contribute to tertiary protein structure?
R groups
Covalent bonding, ionic bonding, hydrogen bonding, disulfide bridges
19. List two conditions under which proteins may be denatured.
Heat and pH change
20. What is a Chaperonin?
A protein that assists in the folding of other protein molecules (polypeptideprotein)
Nucleic Acids Store and Transmit Hereditary Information
READ: Skim Section 5.5, carefully read text relating to Figures 5. 27 & 5.28 to
answer questions
21. List the major components of a nucleotide, and describe how these monomers are linked to
form a nucleic acid.
Monomer: nucleotide
Sugar, phosphate, nitrogenous base
Bond: Phosphodiester bond
KNOW YOUR CARBONS (1’-5’) ON THE SUGAR RING! Phosphate is linked to sugar
at the 3’ and another at the 5’carbon of the sugar and the nitrogenous base is linked to the
sugar at the 1’ carbon
22. Distinguish between:
a. pyrimidine- C, T or U and purine- A or G
b. nucleotide- phosphate, sugar and nitrogenous base and nucleoside- just the sugar and
nitrogenous base
c. ribose- sugar found in RNA polynucleotide and deoxyribose- sugar found in DNA
polynucleotide
d. 5’ end- 5’ carbon of sugar, place where phosphate is linked to sugar and 3’ end of a
nucleotide 3’ carbon of sugar, place where phosphate of another nucleotide adds to the original
nucleotide.
23. Briefly describe the three-dimensional structure of DNA.
Two polynucleotide chains wrapped around one another to form a double helix
24. List at least 3 main differences between DNA and RNA.
DNA-double stranded
RNA- single stranded
DNA- ATCG nuclotides
RNA- AUCG nucleotides
THIS IS IMPORTANT!!!
DNA- deoxyribose sugar (no OH group on 2’ carbon of the sugar ring)
RNA- ribose sugar (OH group IS on 2’ carbon of the sugar ring)
Suggested end of chapter SELF-QUIZ questions:
#1, 3, 4-9
See textbook appendix for answers