- Explain the characteristics of biomolecules such as carbohydrates, proteins, nucleic acids, and hormones.
- Classify carbohydrates, proteins, nucleic acids, and vitamins based on their structures.
- Explain the difference between DNA and RNA.
- Describe the role of biomolecules in biosystems.
Biomolecules
Study Action Plan (Sorted by Difficulty)
Learning Objectives
TopPractice, Analyze & Improve
Dont just read—test your knowledge! Unlock the Student Workspace to take chapter tests and get instant performance insights.
Deep Analytics
Peer Comparison
Track Progress
Claim Free Account100% Free • No credit card required
Revision Notes & Summary
TopNotes on Biomolecules
10.1 Carbohydrates
- Definition: Carbohydrates are optically active polyhydroxy aldehydes or ketones or molecules which provide such units on hydrolysis.
- Classification: Broadly classified into three groups:
- Monosaccharides
- Disaccharides
- Polysaccharides
- Examples: Cane sugar, glucose, starch.
- General Formula: Cₓ(H₂O)ᵥ (e.g., glucose: C₆H₁₂O₆).
- Functions:
- Energy source for mammals (e.g., glucose from starch digestion).
- Storage molecules (starch in plants, glycogen in animals).
10.2 Proteins
- Definition: Proteins are polymers of about twenty different α-amino acids linked by peptide bonds.
- Essential Amino Acids: Cannot be synthesized by the body; must be obtained from the diet (e.g., Isoleucine, Arginine).
- Denaturation: Change in pH or temperature can disturb secondary and tertiary structures, affecting function.
- Enzymes: Biocatalysts that speed up reactions; specific to substrates.
10.3 Nucleic Acids
- Definition: Polymers of nucleotides, consisting of a base, a pentose sugar, and a phosphate moiety.
- Types: DNA and RNA.
- DNA: Contains deoxyribose, double-stranded, includes bases adenine, guanine, cytosine, and thymine.
- RNA: Contains ribose, single-stranded, includes adenine, guanine, cytosine, and uracil.
- Functions: Genetic information transfer, protein synthesis.
10.4 Vitamins
- Definition: Organic compounds required in small amounts for specific biological functions.
- Classification:
- Fat-soluble (A, D, E, K)
- Water-soluble (B group, C)
- Importance: Deficiency can lead to diseases.
10.5 Hormones
- Definition: Molecules acting as intercellular messengers produced by endocrine glands.
- Types: Steroids (e.g., estrogens), polypeptides (e.g., insulin), amino acid derivatives (e.g., epinephrine).
- Functions: Regulate biological activities, maintain homeostasis (e.g., insulin regulates blood glucose levels).
10.6 Key Concepts
- Glycosidic Linkage: Bond between monosaccharides in carbohydrates.
- Peptide Linkage: Bond between amino acids in proteins.
- Denaturation: Loss of protein structure and function due to external stress.
- Complementary Strands: DNA strands are not identical but complementary, crucial for replication.
Practice Test – MCQs, True/False
TopMultiple Choice Questions
A.
Sucrose hydrolysis yields glucose and fructose, and the mixture is laevorotatory.
B.
Sucrose hydrolysis yields two glucose molecules, and the mixture is dextrorotatory.
C.
Sucrose hydrolysis yields glucose and galactose, and the mixture is laevorotatory.
D.
Sucrose hydrolysis yields glucose and fructose, and the mixture is dextrorotatory.
Correct Answer: A
Solution:
Sucrose hydrolysis yields an equimolar mixture of D-(+)-glucose and D-(-)-fructose. The laevorotation of fructose is more than the dextrorotation of glucose, making the mixture laevorotatory, hence called invert sugar.
Chapter Concept:
Glycosidic Linkage and Disaccharides
A.
A polypeptide is a polymer of monosaccharides linked by glycosidic bonds.
B.
A polypeptide is a polymer of nucleotides linked by phosphodiester bonds.
C.
A polypeptide is a polymer of amino acids linked by peptide bonds.
D.
A polypeptide is a polymer of fatty acids linked by ester bonds.
Correct Answer: C
Solution:
A polypeptide is a polymer of amino acids linked by peptide bonds, which are formed by the condensation of the carboxyl group of one amino acid with the amino group of another.
Chapter Concept:
Peptide Linkage and Polypeptides
A.
Oxidation with nitric acid
B.
Cyclization to form a hemiacetal
C.
Hydrolysis of sucrose
D.
Formation of glucose pentaacetate
Correct Answer: B
Solution:
The formation of two anomeric forms, α and β, of glucose is due to cyclization, which forms a hemiacetal structure.
Chapter Concept:
Glucose Structure and Reactions
A.
Glucose is a ketose.
B.
Glucose exists in a cyclic hemiacetal form.
C.
Glucose is a non-reducing sugar.
D.
Glucose reacts with acetic anhydride.
Correct Answer: B
Solution:
Glucose does not give a positive Schiff's test because it exists in a cyclic hemiacetal form, which prevents the free aldehyde group from reacting.
Chapter Concept:
Glucose Structure and Reactions
A.
RNA stores genetic information and can self-duplicate.
B.
RNA is involved in protein synthesis.
C.
RNA forms the double helix structure of chromosomes.
D.
RNA is a structural component of the cell wall.
Correct Answer: B
Solution:
RNA molecules participate directly in protein synthesis, unlike DNA which stores genetic information.
Chapter Concept:
DNA vs RNA
A.
Hydrogen bond
B.
Ionic bond
C.
Phosphodiester bond
D.
Disulfide bond
Correct Answer: C
Solution:
Nucleotides in a DNA strand are connected by phosphodiester linkages between the 5' and 3' carbon atoms of the pentose sugar.
Chapter Concept:
Nucleic Acid Structure and Function
A.
Formation of n-hexane with HI
B.
Formation of oxime with hydroxylamine
C.
Formation of gluconic acid with bromine water
D.
Formation of glucose pentaacetate with acetic anhydride
Correct Answer: C
Solution:
The oxidation of glucose to gluconic acid with bromine water confirms the presence of an aldehydic group.
Chapter Concept:
Glucose Structure and Reactions
A.
Pyranose
B.
Furanose
C.
Hexose
D.
Pentose
Correct Answer: B
Solution:
Fructose forms a five-membered cyclic furanose structure through the addition of the -OH group at C-5 to the ketonic group.
Chapter Concept:
Fructose Structure and Cyclic Forms
A.
Glucose contains a ketone group.
B.
Glucose contains a carbonyl group.
C.
Glucose contains a hydroxyl group.
D.
Glucose contains a carboxylic acid group.
Correct Answer: B
Solution:
The formation of a cyanohydrin with indicates the presence of a carbonyl group (>C=O) in glucose.
Chapter Concept:
Glucose Structure and Reactions
A.
Monosaccharides can be hydrolyzed into simpler units.
B.
Oligosaccharides yield two to ten monosaccharide units upon hydrolysis.
C.
Polysaccharides are sweet in taste and are reducing sugars.
D.
All carbohydrates fit the general formula .
Correct Answer: B
Solution:
Oligosaccharides are carbohydrates that yield two to ten monosaccharide units upon hydrolysis. Monosaccharides cannot be hydrolyzed further, polysaccharides are not sweet in taste, and not all carbohydrates fit the formula .
Chapter Concept:
Carbohydrate Classification and Structure
Experience the StudyTunnel Method
We do not just give you mock tests. We guide you through a gamified, AI-driven learning path designed to guarantee mastery.
Step 1: Practicing the Concepts
Biomolecules
Step 2: Master Boss Exam
Locked • Full Phase AssessmentStep 3: Redemption Arena
Locked • AI Weakness TrackerTrue or False
Correct Answer: False
Solution:
Sucrose is a non-reducing sugar because the reducing groups of glucose and fructose are involved in glycosidic bond formation, thus they are not free.
Chapter Concept :
Glycosidic Linkage and Disaccharides
Correct Answer: True
Solution:
Naturally occurring α-amino acids have an asymmetric α-carbon atom, making them optically active, and they predominantly exist in the L-configuration.
Chapter Concept :
Amino Acid Properties and Classification
Correct Answer: True
Solution:
Naturally occurring α-amino acids, except glycine, have an asymmetric α-carbon atom which makes them optically active. Most of these amino acids have L-configuration.
Chapter Concept :
Amino Acid Properties and Classification
Correct Answer: True
Solution:
Thyroxine is indeed an iodinated derivative of tyrosine. A deficiency in thyroxine, often due to low iodine intake, can lead to hypothyroidism, characterized by symptoms such as lethargy and obesity.
Chapter Concept :
Hormonal Regulation and Function
Correct Answer: True
Solution:
Glucose reacts with to form a cyanohydrin, which indicates the presence of a carbonyl group in its structure.
Chapter Concept :
Glucose Structure and Reactions
Correct Answer: True
Solution:
Insulin lowers blood glucose levels, while glucagon raises them. These hormones work together to maintain glucose homeostasis.
Chapter Concept :
Hormonal Regulation and Function
Correct Answer: True
Solution:
Enzymes act as biocatalysts by lowering the activation energy required for reactions to proceed, which is a key characteristic shared with chemical catalysts.
Chapter Concept :
Enzyme Catalysis and Mechanism
Correct Answer: True
Solution:
DNA contains -D-2-deoxyribose, while RNA contains -D-ribose, which differentiates the two types of nucleic acids.
Chapter Concept :
Nucleic Acid Structure and Function
Correct Answer: True
Solution:
Fructose, a ketohexose, forms five-membered cyclic furanose structures through the addition of the hydroxyl group at to the ketonic group, resulting in the formation of α- and β-D-fructofuranose.
Chapter Concept :
Fructose Structure and Cyclic Forms
Correct Answer: False
Solution:
The statement is false. RNA contains the sugar ribose, while DNA contains the sugar 2-deoxyribose.
Chapter Concept :
DNA vs RNA
I can help you understand Biomolecules better. Ask me anything!
Summarize the main points of Biomolecules.
What are the most important terms to remember here?
Explain this concept like I'm five.
Give me a quick 3-question practice quiz.