Download Proteins perform most functions in the cell [1].

GUIDED READING - Ch. 5 - Section 4
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Proteins perform most functions in the cell [1].
1. a. What is a protein?
b. Why are they so important to living organisms?
2. List at least six examples of different ways proteins help the body function.
a.
b.
c.
d.
e.
f.
3. a. Though lipids are macromolecules, they are not considered polymers. However, like
carbohydrates, proteins are considered polymers. What is the monomer of a protein polymer
called?
b. Describe the basic structure of an amino acid.
c. Draw a generic amino acid.
d. Animals such as humans use 20 different amino acids. What makes one amino acid differ from
another in chemical properties?
e. Using the same format as found in your text, research online, and then neatly draw and label the
amino acids phenylalanine and threonine.
f.
Based on what you learned about water chemistry, how do you think these two amino acids drawn
above differ in their interactions with water and why? Be specific and detailed in your explanation,
brining in the vocabulary and concepts you studies in chapter 4.
4. a. What is a chain of amino acids called?
b. What is the chemical reaction called that is used to covalently bond amino acids together?
c. Based on the information in your text, explain with the use of a drawing the formation of a
dipeptide (two amino acids bonded together) consisting of the amino acids leucine and serine
(shown in your text).
5. If a chain of amino acids is actually a polypeptide and not a protein as was first mentioned in this
section. Explain the relationship between amino acids, polypeptides, and proteins. [1]
6. What makes one polypeptide and, thereby, each protein unique?
7. The sequence of amino acids in a polypeptide is called the proteins primary structure. However,
proteins are large three-dimensional macromolecules. What makes a protein functional?
8. Explain the two interactions that determine a polypeptide, and therefore protein’s, three-dimensional
shape.
a.
b.
9. Amino acids are classified as hydrophobic or hydrophilic based on the properties of their side chains
or R groups. Where are you most likely to find hydrophobic amino acids and hydrophilic amino acids
in a properly folded protein.
10. a. What is it called when a protein looses its three-dimensional shape?
b. What are three environmental variables that, if changed, can cause this to occur?
i.
ii.
iii.
c. Referring to your answer in 10.b. Why specifically does excess heat, for example, cause a protein
to denature?
d.
What happens to a proteins ability to function when it denatures and why?
[1] Campbell, Heyden, Williamson. 2006. Biology: Exploring Life. Prentice Hall: Boston, MA.