UNE BioChem 1005 Final Exam Questions
With Complete Solutions
Course
UNE BioChemistry
1. Structure and Function of Proteins
Question:
What are the four levels of protein structure, and how do they contribute to protein function?
Solution:
Primary structure: Amino acid sequence (determined by peptide bonds).
Secondary structure: α-helices & β-sheets (stabilized by hydrogen bonds).
Tertiary structure: 3D folding (due to hydrophobic interactions, ionic bonds, disulfide
bridges).
Quaternary structure: Multiple polypeptide chains (e.g., hemoglobin).
Importance: Structure determines function; misfolding leads to diseases (e.g.,
Alzheimer's, sickle cell anemia).
2. Role of Enzymes in Metabolism
Question:
How do enzymes speed up biochemical reactions, and what factors affect their activity?
Solution:
Catalysts that lower activation energy without being consumed.
Mechanisms: Substrate binding → Transition state stabilization → Product release.
Factors affecting activity:
o Temperature (optimal ~37°C for humans).
o pH (e.g., pepsin in stomach ~pH 2, amylase in saliva ~pH 7).
o Substrate concentration (Michaelis-Menten kinetics, Km & Vmax).
o Inhibitors (competitive, non-competitive, uncompetitive).
,3. ATP and Cellular Energy Production
Question:
How does ATP function as an energy carrier in cells?
Solution:
ATP (Adenosine Triphosphate) stores energy in phosphate bonds.
Hydrolysis of ATP → ADP + Pi releases energy (~30.5 kJ/mol).
Used in active transport, muscle contraction, biosynthesis.
Regenerated via glycolysis, TCA cycle, oxidative phosphorylation.
4. Glycolysis vs. Gluconeogenesis
Question:
Compare glycolysis and gluconeogenesis in terms of location, key enzymes, and regulation.
Solution:
Feature Glycolysis Gluconeogenesis
Location Cytoplasm Liver, kidney (cyto + mito)
Purpose Glucose → ATP Glucose synthesis
Pyruvate carboxylase, PEPCK, FBPase-1,
Key Enzymes Hexokinase, PFK-1, Pyruvate kinase
G6Pase
Stimulated by insulin, inhibited by
Regulation Stimulated by glucagon, inhibited by insulin
ATP
5. Lipid Metabolism: Beta-Oxidation
Question:
What are the key steps in fatty acid β-oxidation?
Solution:
Occurs in mitochondria, breaks down fatty acids for ATP production.
Steps:
, 1. Activation (Fatty acid → Acyl-CoA, via Acyl-CoA synthetase).
2. Transport (via Carnitine Shuttle).
3. Beta-Oxidation:
Oxidation (FADH₂ produced).
Hydration.
Oxidation (NADH produced).
Cleavage (Acetyl-CoA formed).
Each cycle produces: 1 Acetyl-CoA, 1 NADH, 1 FADH₂.
6. Role of the Citric Acid Cycle in Energy Production
Question:
What are the key products of the citric acid (Krebs) cycle per acetyl-CoA molecule?
Solution:
Occurs in mitochondria.
Key products per acetyl-CoA:
o 3 NADH (Electron transport chain → ATP).
o 1 FADH₂ (ETC → ATP).
o 1 GTP (converted to ATP).
o 2 CO₂ (waste product).
Regulation:
o Activated by ADP.
o Inhibited by ATP, NADH.
7. Electron Transport Chain and Oxidative Phosphorylation
Question:
How does the electron transport chain (ETC) generate ATP?
Solution:
, Located in the inner mitochondrial membrane.
Steps:
1. NADH & FADH₂ donate electrons → Complex I & II.
2. Electrons move through Complex III & IV → Oxygen (final acceptor, forms H₂O).
3. Proton gradient (H⁺ pumped into intermembrane space).
4. ATP Synthase uses gradient → Converts ADP + Pi → ATP.
Yields: 1 NADH → ~2.5 ATP, 1 FADH₂ → ~1.5 ATP.
8. DNA Replication: Key Enzymes
Question:
What are the key enzymes involved in DNA replication?
Solution:
Helicase: Unwinds DNA strands.
Topoisomerase: Relieves supercoiling.
Primase: Synthesizes RNA primer.
DNA Polymerase III: Adds nucleotides (5’→3’).
DNA Polymerase I: Removes RNA primer, fills gaps.
Ligase: Seals Okazaki fragments.
Replication is semi-conservative: Each new DNA has one old & one new strand.
9. Role of Hormones in Blood Glucose Regulation
Question:
How do insulin and glucagon regulate blood glucose levels?
Solution:
Insulin (released by β-cells, pancreas):
o Lowers blood glucose.
o Increases glucose uptake (GLUT4), glycogenesis, lipogenesis.
With Complete Solutions
Course
UNE BioChemistry
1. Structure and Function of Proteins
Question:
What are the four levels of protein structure, and how do they contribute to protein function?
Solution:
Primary structure: Amino acid sequence (determined by peptide bonds).
Secondary structure: α-helices & β-sheets (stabilized by hydrogen bonds).
Tertiary structure: 3D folding (due to hydrophobic interactions, ionic bonds, disulfide
bridges).
Quaternary structure: Multiple polypeptide chains (e.g., hemoglobin).
Importance: Structure determines function; misfolding leads to diseases (e.g.,
Alzheimer's, sickle cell anemia).
2. Role of Enzymes in Metabolism
Question:
How do enzymes speed up biochemical reactions, and what factors affect their activity?
Solution:
Catalysts that lower activation energy without being consumed.
Mechanisms: Substrate binding → Transition state stabilization → Product release.
Factors affecting activity:
o Temperature (optimal ~37°C for humans).
o pH (e.g., pepsin in stomach ~pH 2, amylase in saliva ~pH 7).
o Substrate concentration (Michaelis-Menten kinetics, Km & Vmax).
o Inhibitors (competitive, non-competitive, uncompetitive).
,3. ATP and Cellular Energy Production
Question:
How does ATP function as an energy carrier in cells?
Solution:
ATP (Adenosine Triphosphate) stores energy in phosphate bonds.
Hydrolysis of ATP → ADP + Pi releases energy (~30.5 kJ/mol).
Used in active transport, muscle contraction, biosynthesis.
Regenerated via glycolysis, TCA cycle, oxidative phosphorylation.
4. Glycolysis vs. Gluconeogenesis
Question:
Compare glycolysis and gluconeogenesis in terms of location, key enzymes, and regulation.
Solution:
Feature Glycolysis Gluconeogenesis
Location Cytoplasm Liver, kidney (cyto + mito)
Purpose Glucose → ATP Glucose synthesis
Pyruvate carboxylase, PEPCK, FBPase-1,
Key Enzymes Hexokinase, PFK-1, Pyruvate kinase
G6Pase
Stimulated by insulin, inhibited by
Regulation Stimulated by glucagon, inhibited by insulin
ATP
5. Lipid Metabolism: Beta-Oxidation
Question:
What are the key steps in fatty acid β-oxidation?
Solution:
Occurs in mitochondria, breaks down fatty acids for ATP production.
Steps:
, 1. Activation (Fatty acid → Acyl-CoA, via Acyl-CoA synthetase).
2. Transport (via Carnitine Shuttle).
3. Beta-Oxidation:
Oxidation (FADH₂ produced).
Hydration.
Oxidation (NADH produced).
Cleavage (Acetyl-CoA formed).
Each cycle produces: 1 Acetyl-CoA, 1 NADH, 1 FADH₂.
6. Role of the Citric Acid Cycle in Energy Production
Question:
What are the key products of the citric acid (Krebs) cycle per acetyl-CoA molecule?
Solution:
Occurs in mitochondria.
Key products per acetyl-CoA:
o 3 NADH (Electron transport chain → ATP).
o 1 FADH₂ (ETC → ATP).
o 1 GTP (converted to ATP).
o 2 CO₂ (waste product).
Regulation:
o Activated by ADP.
o Inhibited by ATP, NADH.
7. Electron Transport Chain and Oxidative Phosphorylation
Question:
How does the electron transport chain (ETC) generate ATP?
Solution:
, Located in the inner mitochondrial membrane.
Steps:
1. NADH & FADH₂ donate electrons → Complex I & II.
2. Electrons move through Complex III & IV → Oxygen (final acceptor, forms H₂O).
3. Proton gradient (H⁺ pumped into intermembrane space).
4. ATP Synthase uses gradient → Converts ADP + Pi → ATP.
Yields: 1 NADH → ~2.5 ATP, 1 FADH₂ → ~1.5 ATP.
8. DNA Replication: Key Enzymes
Question:
What are the key enzymes involved in DNA replication?
Solution:
Helicase: Unwinds DNA strands.
Topoisomerase: Relieves supercoiling.
Primase: Synthesizes RNA primer.
DNA Polymerase III: Adds nucleotides (5’→3’).
DNA Polymerase I: Removes RNA primer, fills gaps.
Ligase: Seals Okazaki fragments.
Replication is semi-conservative: Each new DNA has one old & one new strand.
9. Role of Hormones in Blood Glucose Regulation
Question:
How do insulin and glucagon regulate blood glucose levels?
Solution:
Insulin (released by β-cells, pancreas):
o Lowers blood glucose.
o Increases glucose uptake (GLUT4), glycogenesis, lipogenesis.
