Rucete ✏ Campbell Biology In a Nutshell
Unit 1 THE CHEMISTRY OF LIFE — Concept 5.4 Proteins Include a Diversity of Structures, Resulting in a Wide Range of Functions — Practice Questions
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1. What are proteins made of?
- Sugars
- Nucleotides
- Amino acids
- Fatty acids
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3. Amino acids
2. What type of bond links amino acids together?
- Glycosidic bond
- Ester bond
- Peptide bond
- Hydrogen bond
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3. Peptide bond
3. Which part of an amino acid varies among different amino acids?
- Amino group
- Carboxyl group
- R group (side chain)
- Central carbon
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3. R group (side chain)
4. What determines a protein’s three-dimensional structure?
- The number of peptide bonds
- The sequence of amino acids
- The presence of water
- The amount of nitrogen
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2. The sequence of amino acids
5. What is the polymer of amino acids called?
- Polysaccharide
- Polypeptide
- Nucleotide
- Fat
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2. Polypeptide
6. What determines the function of a protein?
- Its length
- Its color
- Its shape
- Its location
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3. Its shape
7. Which level of protein structure is the sequence of amino acids?
- Primary
- Secondary
- Tertiary
- Quaternary
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1. Primary
8. What stabilizes the alpha helix and beta pleated sheet structures?
- Peptide bonds
- Hydrogen bonds
- Ionic bonds
- Disulfide bridges
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2. Hydrogen bonds
9. Which level of structure involves interactions among R groups?
- Primary
- Secondary
- Tertiary
- Quaternary
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3. Tertiary
10. What is quaternary structure in proteins?
- The folding of a single polypeptide chain
- The amino acid sequence
- The assembly of multiple polypeptide chains
- The shape of the R groups
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3. The assembly of multiple polypeptide chains
11. What is an example of a protein with quaternary structure?
- Insulin
- Hemoglobin
- Glucose
- Cholesterol
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2. Hemoglobin
12. What can cause a protein to denature?
- Stable pH
- Low salt
- Extreme heat
- Normal temperature
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3. Extreme heat
13. What happens during protein denaturation?
- The amino acids break apart
- The protein folds more tightly
- The protein loses its shape and function
- The protein changes into DNA
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3. The protein loses its shape and function
14. What kind of environment do proteins need to function properly?
- Extremely acidic
- Denatured
- Specific pH and temperature
- Completely dry
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3. Specific pH and temperature
15. What is the name of the protein that helps other proteins fold?
- Enzyme
- Hormone
- Chaperonin
- Antibody
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3. Chaperonin
16. What is the role of enzymes?
- Store energy
- Speed up chemical reactions
- Transport oxygen
- Build membranes
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2. Speed up chemical reactions
17. What determines how an enzyme works?
- Its amino acid sequence and shape
- Its sugar content
- Its DNA sequence
- Its lipid content
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1. Its amino acid sequence and shape
18. What part of the amino acid gives each one its unique properties?
- Carboxyl group
- Amino group
- R group (side chain)
- Peptide bond
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3. R group (side chain)
19. What type of interactions help stabilize tertiary structure?
- Peptide bonds only
- Hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic interactions
- Water molecules
- ATP and glucose
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2. Hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic interactions
20. What is the general shape of a globular protein?
- Long and linear
- Folded and spherical
- Ring-shaped
- Flat and sheet-like
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2. Folded and spherical
21. What kind of protein is collagen?
- Globular protein
- Hormone
- Fibrous protein
- Enzyme
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3. Fibrous protein
22. Which structure is lost first during protein denaturation?
- Primary
- Secondary
- Peptide bonds
- DNA sequence
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2. Secondary
23. What does a chaperonin protein do inside a cell?
- Breaks down amino acids
- Assembles DNA strands
- Provides a safe environment for polypeptides to fold
- Transports sugars
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3. Provides a safe environment for polypeptides to fold
24. What determines the primary structure of a protein?
- Type of cell
- Length of the gene
- Sequence of nucleotides in the gene encoding the protein
- Protein function
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3. Sequence of nucleotides in the gene encoding the protein
25. What happens if a protein is folded incorrectly?
- It works more efficiently
- It gains new functions
- It may lose function or cause diseases
- It turns into DNA
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3. It may lose function or cause diseases
26. Which type of interaction is critical for maintaining tertiary protein structure but not primary structure?
- Peptide bonds
- Covalent bonds between carbon atoms
- Hydrophobic interactions between side chains
- Phosphodiester bonds
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3. Hydrophobic interactions between side chains
27. What functional groups are directly involved in the formation of a peptide bond?
- Hydroxyl and phosphate
- Amino and carboxyl
- Carboxyl and methyl
- Sulfhydryl and phosphate
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2. Amino and carboxyl
28. Which of the following contributes to the specificity of protein folding?
- The sequence of R groups in the polypeptide
- The order of nucleotides in tRNA
- The number of hydrogen bonds in DNA
- The ratio of saturated to unsaturated fats
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1. The sequence of R groups in the polypeptide
29. Disulfide bridges are covalent bonds that typically form between which amino acid side chains?
- Tyrosine
- Arginine
- Cysteine
- Serine
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3. Cysteine
30. What structural level of a protein is destroyed during complete denaturation?
- Primary only
- Tertiary and quaternary
- Only secondary
- All levels except primary
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4. All levels except primary
31. Which of the following protein structures includes alpha helices and beta pleated sheets?
- Primary
- Secondary
- Tertiary
- Quaternary
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2. Secondary
32. How do chaperonins assist in protein folding?
- By forming peptide bonds
- By preventing misfolding through isolation of the polypeptide
- By catalyzing hydrolysis
- By shortening amino acid chains
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2. By preventing misfolding through isolation of the polypeptide
33. Which factor does NOT influence tertiary structure?
- Hydrogen bonding
- Ionic interactions
- Disulfide bonds
- Number of nucleotides
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4. Number of nucleotides
34. What is the function of the R group in an amino acid?
- To form peptide bonds
- To provide identity and determine properties
- To carry genetic information
- To form DNA helices
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2. To provide identity and determine properties
35. Which type of protein structure involves the overall 3D folding pattern of a single polypeptide chain?
- Primary
- Secondary
- Tertiary
- Quaternary
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3. Tertiary
36. Explain how the sequence of amino acids determines a protein’s structure and function.
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The amino acid sequence (primary structure) determines how the polypeptide folds, forming specific 3D shapes that dictate the protein’s function.
37. What type of bond is responsible for linking amino acids into a polypeptide chain?
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Peptide bonds, which are covalent bonds formed between the amino group of one amino acid and the carboxyl group of another.
38. Describe the difference between secondary and tertiary protein structure.
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Secondary structure involves local folding (alpha helices and beta sheets) stabilized by hydrogen bonds, while tertiary structure is the overall 3D shape formed by R-group interactions.
39. What causes denaturation in proteins, and what happens during this process?
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Changes in pH, temperature, or salt disrupt weak bonds, causing the protein to unfold and lose its functional shape.
40. Why is protein shape so important to its function?
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Because function depends on the specific fit between a protein and its target (e.g., enzyme and substrate), and this fit is determined by shape.
41. What are chaperonin proteins and how do they assist in protein folding?
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Chaperonins are helper proteins that provide a protected environment for polypeptides to fold properly without interference.
42. How can a single amino acid substitution affect a protein?
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It can alter folding and shape, potentially disrupting function or causing diseases like sickle-cell anemia.
43. What kinds of interactions stabilize tertiary structure?
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Hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions among R groups.
44. Why is primary structure considered the most fundamental level of protein structure?
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Because it determines all higher levels of structure and ultimately the protein's function.
45. How is quaternary structure different from tertiary structure?
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Quaternary structure involves multiple polypeptide subunits, while tertiary structure is the folding of a single polypeptide.
46. What is the role of the R group in an amino acid?
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The R group gives each amino acid its unique chemical properties and influences how it interacts in protein folding.
47. Why are hydrogen bonds crucial for protein secondary structure?
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They stabilize repetitive folding patterns like alpha helices and beta sheets.
48. How do enzymes demonstrate the importance of protein structure?
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Their specific 3D shapes determine substrate binding and catalytic function, showing that structure directly affects activity.
49. What structural feature makes fibrous proteins like collagen different from globular proteins?
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Fibrous proteins have long, extended shapes for support and strength, while globular proteins are compact and folded for dynamic functions.
50. What does it mean when a protein is said to be "denatured," and can it be reversed?
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Denatured means it has lost its structure and function due to environmental change; sometimes it can refold if conditions return to normal, but not always.