Download Unit 17 Handout - Chavis Biology

UNIT 17: Protein Structure and Function
Essential Idea(s):
Proteins have a very wide range of functions in living organisms.
IB Assessment Statements
Amino Acids
2.1.S1: Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
 Draw the generalized structure of an amino acid.
 Label the amine group, carboxyl group, alpha carbon and R group on an amino acid.
2.4.U2: There are 20 different amino acids in polypeptides synthesized on ribosomes.
 State the number of amino acids used by living organisms to make polypeptides.
 Given an image of an amino acid, classify the amino acid chemical properties based on R group
properties.
 Outline the role vitamin C plays in the conversion of proline to hydroxyproline.
D.1.U4: Some fatty acids and some amino acids are essential.
 Outline the concept of “conditionally essential” using amino acid examples.
D.1.U1: Essential nutrients cannot be synthesized by the body, therefore they have to be included in the diet.
 Define “essential” as related to dietary nutrients.
 Define “non-essential” as related to dietary nutrients.
D.1.U5: Lack of essential amino acids affects the production of proteins.
 Outline the effect of protein deficiency malnutrition on children and adults.
2.4.NOS: Looking for patterns, trends, and discrepancies- most but not all organisms assemble proteins from
the same amino acids.
 Explain the trend of organisms assembly of polypeptides from the same amino acids.
 Describe a discrepancy of the trend of all organisms using the same amino acids to assemble
polypeptides.
Protein Folding (Structure)
2.4.U1: Amino acids are linked together by condensation to form polypeptides.
 Describe polypeptide chain formation in terms of the formation of peptide bonds and condensation
reactions.
 Determine the number of peptide bonds given the number of amino acids in a polypeptide.
 Define dipeptide, oligopeptides and polypeptide.
2.4.S1: Drawing molecular diagrams to show the formation of a peptide bond.
 Draw peptide bond formation in a condensation reactions.
2.4.U3: Amino Acids can be linked together in any sequence giving a huge range of possible polypeptides.
 Calculate the possible number of amino acid sequences given n number of amino acids.
2.4.U4: The amino acid sequence of polypeptides is coded for by genes.
 Outline the relationship between genes and polypeptides.
7.3.U7: The sequence and number of amino acids in the polypeptide is the primary structure.
 Describe the primary structure of a protein, including the type of bonding involved.
7.3.U8: The secondary structure is the formation of alpha helices and beta pleated sheets stabilized by
hydrogen bonding.
 Describe the secondary structure of a protein, including the type of bonding involved.
 Identify the alpha-helix and beta-pleated sheet in images of protein structure.
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7.3.U9: The tertiary structure is the further folding of the polypeptide stabilized by interactions between R
groups.
 Describe the tertiary structure of a protein, including the types of R group interactions involved.
 Explain how the chemical characteristics of R groups in the polypeptide chain affect protein folding.
2.4.U5: A protein may consist of a single polypeptide or more than one polypeptide linked together.
 Outline the structure and function of three example proteins composed of two or more polypeptides
linked together.
2.4.U6: The amino acid sequence determines the three-dimensional conformation of a protein.
 Contrast the structure of globular proteins with the structure of fibrous proteins.
 Describe the structure of membrane bound globular proteins.
7.3.10: The quaternary structure exists in proteins with more than one polypeptide chain (may also involve the
binding of a prosthetic group to form a conjugated protein).
 Outline the quaternary structure of protein folding.
 Describe the structure of a conjugated protein, including the prosthetic group.
Protein Function
2.4.U8: Every individual has a unique proteome.
 Define proteome.
 Contrast proteome with genome.
2.4.U7: Living organisms synthesize many different proteins with a wide range of functions.
 Contrast the generalized function of globular proteins with generalized function of fibrous proteins.
 List ten functions of proteins in a cell or organism.
 Describe the function of enzyme proteins.
 Describe the function of hormone proteins.
 Describe the function of immunoglobulin proteins.
 Describe the function of pigment proteins.
 Describe the function of structural proteins.
2.4.A1: Rubisco, insulin, immunoglobulins, rhodopsin, collagen and spider silk as examples of the range of
protein functions.
 State the function of each of the following proteins:
o rubisco
o insulin
o immunoglobulin
o rhodopsin
o collagen
o spider silk
o actin
o myosin
o casein
o hemoglobin
o acetylcholine receptor
o oxytocin
o prolactin
o ferritin
o billirubin
o fibrinogen
o transferrin
o albumin
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Amino Acids
1. Proteins do the nitty-gritty jobs in every living cell.
2. Proteins are made of long strings of individual building blocks known as amino acids.
a. Amino acids contain an amino group, a carboxyl group, a carbon and a unique R group.
Generalized Amino Acid
i. Polar R group: ____________________________________
ii. Non polar R group: ________________________________
iii. Ionically charged R group: ____________________________________
b. There are _______commonly occurring amino acids that are found in proteins
c. ____________________________________________ are those that
must be ingested in the diet.
d. Some amino acids are “conditionally essential”.
e. ___________________ __________________ Malnutrition
i. Kwashiorkor
ii. Marasmus
3. __________________________join amino acids
a. It’s a condensation reaction (meaning that
________________________________________)
b. Two amino acids form a ________________________
c. ______________________________ are formed from more than
two amino acids bonded together
4. Proteins have four levels of organization
a. _______________________________ is the amino acid sequence (the polypeptide chain)
i. The amino acid sequence is _______________ ______________________________________ and is unique for
each kind of protein
ii. The amino acid sequence determines how the polypeptide will fold into its 3D shape
iii. Even a slight change in the amino acid sequence can cause the protein to malfunction

For example, mis-formed __________________ causes _______________________
b. ____________________________results from __________________________________between _________________of one amino
acid and _____________________of another
i. The ______________________________ is a coiled secondary structure

due to a ___________________________________________________________

Examples: hemoglobin, ketatin, lysozyme
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ii. The _____________________________________ is formed by amino acids in parallel chains

hydrogen bonds between parallel parts of the backbone

Example: silk
iii. A single polypeptide may
have portions with both
types of the structure
c. __________________________ depends on
the interactions among the
___________________________
i. _____________________
interactions: amino acids
with hydrophobic side chains
cluster in the core of the
protein, out of contact with
______________
ii. Hydrogen bonds between
______ _________________
iii. _______________________ between
positively and negatively
charged side chains
iv. _______________________ (strong
covalent bonds) between
sulfur atoms in the amino
acid ________________
d. _______________________________ results
from interactions among _________________________ _________________________ (for example, hemoglobin is
composed of 4 polypeptide chains)
5. The folding of proteins is aided by other proteins called ___________________________
a. Act as _____________________________as proteins fold into their final conformation
b. Research into chaperones is a hot area of research in biology
6. _____________________ results in disruption of the secondary, tertiary, or quaternary structure of the protein
a. Denaturation may be due to changes in ________, _________________, or various ______________.
b. Normal functioning is lost upon denaturation, which is often irreversible.
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7. Folded proteins are placed into two general categories
a. ____________________________________have polypeptide chains organized as strands or sheets
i. _____________________________________
ii. ___________________________ – may be stretchy
b. ____________________________ have their chains folded into compact, _____________________
i. Easily __________________________
Protein Functions - Fill in the Chart After the Presentation
Protein
Name
Collagen
Type
Function in Cell
Type of Cell
Found In
Sketch
Interesting Fact
Structure:
Rubisco
Enzyme:
Insulin
Hormone:
Immunoglobin /
Antibody
Immune
Defense:
Myosin
Pigment:
Rhodopsin
Contraction:
Casein
Storage:
Hemoglobin
Transport:
Acetylcholine
Receptor
Receptor:
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