BIOCHEM LEC

1. What are the three principal areas of biochemistry?

Answer: D) Structural Biochemistry, Metabolism, Molecular Genetics

Explanation: Biochemistry is generally divided into three primary areas: structural biochemistry (study of
biomolecules), metabolism (study of chemical processes in living organisms), and molecular genetics
(study of genetic information)

2. Which area of biochemistry studies the energy flow in living systems?

Answer: C) Metabolism

Explanation: Metabolism involves the study of energy flow, focusing on processes like catabolism
(breaking down molecules for energy) and anabolism (synthesizing molecules using energy).

3. What feature allows living organisms to adapt over time?

Answer: B) Evolution

Explanation: Evolution is the process through which organisms adapt and develop advantageous traits
over generations.

4. Which molecules form the basis of macromolecules?

Answer: A) Amino acids, sugars, nucleotides, and fatty acids

Explanation: Macromolecules (proteins, carbohydrates, nucleic acids, and lipids) are made of these
fundamental building blocks.

5. The general formula of monosaccharides is

Answer: A) CnH2nOn

Explanation: Monosaccharides, such as glucose and fructose, follow the general formula CnH2nOn,
representing their carbohydrate structure.

6. The aldose sugar is

Answer: A) Glycerose

Explanation: Glycerose is an aldose sugar because it has an aldehyde functional group.

7. A polysaccharide which is of animal origin is

Answer: C) Glycogen

Explanation: Glycogen is the storage form of glucose in animals, stored in the liver and muscles.

8. Which of the following is a reducing sugar?

Answer: A) Sucrose

Explanation: Reducing sugars have a free aldehyde or ketone group capable of acting as a reducing agent.
Sucrose is a non-reducing sugar.

9. The sugar found in RNA is

Answer: A) Ribose

Explanation: Ribose is the pentose sugar present in RNA, whereas DNA contains deoxyribose.

10. Of the eight D-aldohexoses, which is the most abundant in the biological world?

Answer: D) D-Glucose

Explanation: D-Glucose is the most abundant aldohexose and serves as the primary energy source for
many organisms.

11. What is the difference in structure between an aldose and a ketose?

Answer: C) Aldoses have a carbonyl group at C1, while ketoses have it at C2.

Explanation: The carbonyl group is located at different positions: at the end (C1) in aldoses and within the
chain (C2) in ketoses.

12. Which carbon of an aldopentose determines whether the pentose has a D or L configuration?

Answer: C) Carbon-3

Explanation: The D or L configuration is determined by the chiral carbon furthest from the carbonyl
group (e.g., Carbon-3 in aldopentoses).

13. Which carbon is the anomeric carbon in glucose?

Answer: B) Carbon-2

Explanation: In glucose, the anomeric carbon is Carbon-1 (the carbon from the carbonyl group that forms
the glycosidic bond in cyclic form).

14. Why are fats a good source of energy for storage in the body?

Answer: A) Fats are hydrophobic.

Explanation: Fats are dense energy storage molecules because they are hydrophobic, storing large
amounts of energy without water.

15. Oleic acid has a melting point of 16°C. If you convert the cis double bond into a trans double bond,
what would happen to the melting point?

Answer: A) The melting point would increase because the trans configuration allows for tighter packing
of molecules.
Explanation: Trans bonds result in linear structures, allowing tighter packing and raising the melting
point.

27. The members of which class of proteins are insoluble in water and can serve as structural materials?

Answer: D) Fibrous proteins

Explanation: Fibrous proteins, such as collagen and keratin, are structural proteins that are insoluble in
water and provide mechanical support.

28. Why will an amino acid not exist in a non-ionized form at all pH values?

Answer: B) Amino acids contain both an amino group and a carboxyl group, ionizing at different pH
values.

Explanation: The amino group can gain a proton (positive charge), and the carboxyl group can lose a
proton (negative charge), making amino acids ionized at all pH levels.

29. What are conditionally essential amino acids?

Answer: D) Amino acids that become essential under certain conditions.

Explanation: These amino acids are normally synthesized by the body but may need to be obtained from
the diet during periods of illness or stress.

30. Which of the following is considered a complete dietary protein?

Answer: D) Eggs

Explanation: Complete proteins, like eggs, contain all the essential amino acids in adequate amounts for
the body’s needs.

31. At neutral pH, what happens to the amino group (-NH2) of an amino acid?

Answer: C) It becomes part of the carboxylate group

Explanation: At neutral pH, amino acids exist as zwitterions, where the amino group gains a proton (+
charge), and the carboxyl group loses a proton (- charge).

32. Which peptide contains two amino acid residues?

Answer: B) Dipeptide

Explanation: A dipeptide is made up of two amino acids joined by a peptide bond.

33. What is the primary function of oxytocin?

Answer: B) Uterine contraction and lactation

Explanation: Oxytocin is a hormone that stimulates uterine contractions during childbirth and milk release
during breastfeeding.

34. Which process is the unfolding of a protein?

Answer: C) Denaturation

Explanation: Denaturation occurs when a protein loses its native structure due to heat, pH changes, or
chemicals, losing its function

35. Which test records the electrical activity of the heart?

Answer: A) Electrocardiogram (ECG)

Explanation: An ECG measures the heart’s electrical activity to detect abnormalities in rhythm or
function.

36. Which organ enlargement is the most common in Gaucher’s disease?

Answer: B) Hepatosplenomegaly

Explanation: Gaucher’s disease commonly causes an enlarged liver (hepatomegaly) and spleen
(splenomegaly).

37. Krabbe disease is an autosomal recessive genetic disorder. Which of the following best describes this
condition?

Answer: D) A disorder caused by a deficiency in sphingomyelinase

Explanation: Krabbe disease is caused by a lack of an enzyme that breaks down sphingomyelin, leading
to nerve damage.

38. What are angiokeratomas, a common symptom of Fabry’s disease?

Answer: A) Painful nodules in the joints

Explanation: Angiokeratomas are dark red or purple skin lesions often associated with Fabry’s disease.

40. Which of the following is a major structural characteristic of enzymes?

Answer: B) They are mostly globular proteins

Explanation: Enzymes are globular proteins with complex tertiary structures, allowing them to bind
specifically to substrates.

41. What is the difference between a catalyst and an enzyme?

Answer: A) A catalyst is consumed in the reaction, while an enzyme is not.

Explanation: Enzymes, as biological catalysts, are not consumed in reactions, allowing them to be reused.

42. What is an enzyme that lacks its cofactor called?

Answer: A) Apoenzyme

Explanation: An apoenzyme is the inactive form of an enzyme without its non-protein cofactor.

43. Which model describes the enzyme-substrate binding?

Answer: B) Lock and key model

Explanation: The lock and key model suggests that enzymes and substrates fit perfectly, like a key in a
lock.

44. Which of the following is a common example of a drug that uses enzyme inhibition to control blood
pressure?

Answer: A) Enalapril

Explanation: Enalapril is an ACE inhibitor, blocking an enzyme to lower blood pressure.

45. What is the purpose of anabolic pathways?

Answer: A) To break down larger molecules into smaller ones

Explanation: Anabolic pathways build complex molecules from simpler ones, storing
energy.

Biochem Notes

Metabolism

Pages 1–5:

1. Glycolysis: Pathway metabolizing glucose to pyruvate, producing ATP and NADH.

2. Pyruvate: Product of glycolysis; precursor to acetyl-CoA or lactate.
3. Lactate: Produced anaerobically from pyruvate.
4. Acetyl-CoA: Central molecule in metabolism connecting glycolysis, beta-oxidation,
and TCA cycle.
5. Citric Acid Cycle (TCA): Central pathway oxidizing acetyl-CoA to CO₂ while
generating NADH and FADH₂.
6. Beta-Oxidation: Degradation of fatty acids into acetyl-CoA.
7. Pentose Phosphate Pathway: Produces NADPH and ribose-5-phosphate for
biosynthesis.
8. Ketone Bodies: Products of ketogenesis like acetoacetate and beta-
hydroxybutyrate.
9. Glucogenic Amino Acids: Amino acids metabolized into glucose precursors.
10. Ketogenic Amino Acids: Amino acids degraded into ketone body precursors.
Pages 6–10:

11. Oxidative Deamination: Removal of amino groups from amino acids, forming
ammonia.
12. Transamination: Exchange of amino and keto groups between amino acids and
keto acids.
13. Urea Cycle: Pathway converting toxic ammonia into urea for excretion.
14. Carnitine Shuttle: Transports fatty acids into mitochondria for beta-oxidation.
15. Oxidative Phosphorylation: Electron transport coupled with ATP production.

Pages 11–15:

16. Gluconeogenesis: Synthesis of glucose from non-carbohydrate sources.

17. Lipolysis: Breakdown of triglycerides into glycerol and fatty acids.
18. Glycerol Catabolism: Conversion of glycerol into glycolytic intermediates.
19. Nitrogen Metabolism: Pathways for processing nitrogen from amino acids.
20. Phenylketonuria (PKU): Disorder caused by defective phenylalanine metabolism.

Pages 16–20:

21. Glycogenolysis: Breakdown of glycogen into glucose.

22. Fatty Acid Activation: Conversion of fatty acids into acyl-CoA for metabolism.
23. Amino Acid Pool: Free amino acids available for biosynthesis or catabolism.
24. Energy Yield from Glucose: Complete oxidation of glucose produces 30-32 ATP
molecules.

Pages 21–27:

25. Protein Catabolism: Breakdown of proteins into amino acids for energy or building
blocks.
26. Common Metabolic Pathway: Final stages of carbohydrate, lipid, and protein
catabolism converging in TCA cycle.
27. Electron Transport Chain (ETC): Series of complexes transferring electrons to
oxygen, generating a proton gradient for ATP synthesis.

Bioenergetic
Page 1:
1. Metabolism: All the chemical reactions in the body that keep you alive. It includes:
a. Catabolism: Breaking things down to get energy.
b. Anabolism: Building things up like muscles and cells.

Page 2:

2. Mitochondria: The “powerhouses” of the cell where energy is made.

3. Electron Transport Chain (ETC): A series of steps that transfer electrons to make
energy.

Page 3:

4. Citric Acid Cycle (TCA Cycle): A process in mitochondria that breaks down food
into energy.
5. ATP: The energy "currency" your body uses to do everything.

Page 4:

6. Oxidative Phosphorylation: The process that uses oxygen to make a lot of ATP.
7. NADH and FADH₂: Helpers that carry energy to the ETC.

Page 5:

8. Glycolysis: Breaking down sugar (glucose) to make a little energy.

9. Beta-Oxidation: Breaking down fats into smaller parts (acetyl-CoA) for energy.

Page 6:

10. Ketogenesis: Making ketones (backup fuel) when you don’t eat enough carbs.
11. Urea Cycle: How your body gets rid of toxic ammonia by turning it into urea.

Page 7:

12. Transamination: Swapping parts between amino acids to use them for energy or
building.
13. Glucogenic Amino Acids: Amino acids that can turn into sugar for energy.
Page 8:

14. Ketogenic Amino Acids: Amino acids that turn into ketones or fat for energy.
15. Glycogenolysis: Breaking stored sugar (glycogen) into glucose for energy.

Page 9:

16. Pentose Phosphate Pathway: A backup sugar pathway that makes building blocks
and protection against damage.
17. Lipolysis: Breaking down fat into fatty acids and glycerol for energy.

Page 10:

18. Fatty Acid Activation: Getting fatty acids ready for energy production.
19. Carnitine Shuttle: A “transport system” that carries fatty acids into mitochondria.

Page 11:

20. Oxidative Deamination: Removing a part of amino acids to make energy or other
molecules.
21. Electron Carriers: Molecules like NADH and FADH₂ that help transfer energy in
cells.

Page 12:

22. Chemiosmotic Theory: Explains how a flow of protons helps make ATP in
mitochondria.
23. ATP Synthase: A protein machine that makes ATP using protons.

Page 13:

24. Coenzyme A (CoA): A molecule that carries acetyl groups to start the citric acid
cycle.
25. GTP: Another energy molecule similar to ATP.

Page 14:

26. Anaplerotic Reactions: Reactions that refill the supplies needed for the citric acid
cycle.
 27. Energy from Glucose: Breaking down one glucose molecule makes about 30-32
ATP.

Page 15:

28. Heat Energy: The body releases heat to stay warm during chemical reactions.
29. Mechanical Energy: The energy used to move muscles.

Pages 16–27:

30. Proton Gradient: A difference in protons across a membrane that helps make ATP.
31. ADP: The “used” form of ATP that can be turned back into ATP.
32. Phosphorylation: Adding a phosphate to something, often to turn it "on."
33. Anaerobic Respiration: Making energy without oxygen, like when you exercise
hard.
34. Oxidative Stress: Damage from too many reactive oxygen molecules.
35. Thermogenesis: Making heat by burning calories.
36. Brown Fat: A special fat that burns energy to make heat.

1. What is metabolism?
2. a) The process of photosynthesis
3. b) The sum of all biochemical reactions in an organism
4. c) The breakdown of carbohydrates only
5. d) The synthesis of proteins only
6. Answer: b
7. Which process is catabolic?

a) Synthesis of proteins

b) Oxidation of glucose

c) Formation of fatty acids

d) Storage of glycogen

Answer: b

8. Anabolism is characterized by:

a) Breaking down molecules

b) Releasing energy

c) Requiring energy

d) Exclusively occurring in mitochondria

Answer: c

9. What is an amphibolic pathway?

a) A pathway for photosynthesis

b) A pathway that serves both catabolism and anabolism

c) A pathway limited to the cytosol

d) A linear metabolic sequence

Answer: b

10. Where are fatty acids catabolized?

a) Cytosol

b) Ribosomes

c) Mitochondria

d) Lysosomes

Answer: c

Metabolic Pathways

6. What is a metabolic pathway?

a) A random set of reactions
b) A sequence of biochemical reactions
c) A single enzyme reaction
 d) A chemical reaction outside the cell
Answer: b
7. How do metabolic pathways occur?
a) In isolation
b) In a random order
c) Linearly or cyclically
d) Only during starvation
Answer: c
8. What is the role of coenzymes like NAD+ in metabolism?
a) Providing structure to enzymes
b) Transporting hydrogen ions and electrons
c) Acting as a source of glucose
d) None of the above
Answer: b

Cell Structure and Metabolism

9. Which organelle is responsible for energy production?

a) Ribosome
b) Lysosome
c) Mitochondrion
d) Nucleus
Answer: c
10. What is the cytosol?
a) The genetic material of the cell
b) The fluid portion of the cytoplasm
c) The outer membrane of a mitochondrion
d) A type of organelle
Answer: b
11. Which organelle contains hydrolytic enzymes?
a) Ribosomes
b) Lysosomes
c) Mitochondria
d) Golgi apparatus
Answer: b
12. What divides the inner compartments of a mitochondrion?
a) Ribosomes
b) Cristae
 c) The outer membrane
d) Cytoplasm
Answer: b

Key Intermediates of Metabolism

13. What is the most energy-rich molecule?

a) AMP
b) ADP
c) ATP
d) Glucose
Answer: c
14. What is the active part of FAD in metabolism?
a) Adenosine
b) Ribitol
c) Flavin
d) Phosphate
Answer: c
15. The reduced form of FAD is known as:
a) NADH
b) FADH2
c) FADH
d) NAD+

utrition and Metabolism

17. Proteins are primarily used in the body to:

a) Provide long-term energy storage
b) Build and repair tissues
c) Regulate body temperature
d) None of the above
Answer: b
18. Excess carbohydrates in the diet are stored as:
a) Proteins
b) Triacylglycerols
c) Fatty acids
 d) Ketone bodies
Answer: b
19. Which fatty acids are essential?
a) Oleic acid and stearic acid
b) Linoleic acid and linolenic acid
c) Palmitic acid and myristic acid
d) Butyric acid and caproic acid
Answer: b
20. What is a benefit of dietary fiber?
a) Energy production
b) Regular colon function
c) Protein synthesis
d) Fat storage
Answer: b

Biochemical Energy Production

21. Which stage involves digestion of macronutrients?

a) Stage 1
b) Stage 2
c) Stage 3
d) Stage 4
Answer: a
22. Acetyl group formation occurs in which stage?
a) Stage 1
b) Stage 2
c) Stage 3
d) Stage 4
Answer: b
23. The citric acid cycle primarily occurs in:
a) The cytosol
b) Mitochondrial matrix
c) Ribosomes
d) Lysosomes
Answer: b
 24. What is produced in the citric acid cycle?
a) Glucose
b) Reduced coenzymes and CO2
c) Proteins
d) Lipids
Answer: b
25. The electron transport chain requires:
a) Carbon dioxide
b) Oxygen
c) Nitrogen
d) Water
Answer: b
26. What is the main product of oxidative phosphorylation?
a) Glucose
b) ATP
c) Fatty acids
d) NADH
Answer:

The Citric Acid Cycle

27. The Citric Acid Cycle is also known as:

a) Glycolysis
b) Krebs Cycle
c) Calvin Cycle
d) Fatty Acid Cycle
Answer: b
28. What type of reactions are predominant in the Citric Acid Cycle?
a) Hydrolysis and reduction
b) Oxidation and decarboxylation
c) Polymerization and hydrolysis
d) Condensation and substitution
Answer: b
29. The reduced coenzymes from the Citric Acid Cycle are used in:
a) Glycolysis
b) Oxidative phosphorylation
c) Digestion
 d) Anabolism
Answer: b
30. What links the Citric Acid Cycle to ATP production?
a) Acetyl groups
b) NADH and FADH2
c) Amino acids
d) Coenzyme A
Answer: b