Biological Molecules

Question 1

What are the four main classes of biological molecules?

Answer 1

The four main classes of biological molecules are carbohydrates, lipids, proteins, and nucleic acids.

Question 2

What is the general formula of a carbohydrate?

Answer 2

The general formula of a carbohydrate is (CH₂O)n, where “n” represents the number of carbon atoms.

Question 3

Name two monosaccharides commonly found in living organisms.

Answer 3

Two common monosaccharides found in living organisms are glucose and fructose.

Question 4

Explain the difference between a saturated and an unsaturated fatty acid.

Answer 4

A saturated fatty acid has all its carbon atoms bonded to hydrogen atoms, forming a straight chain, while an unsaturated fatty acid contains one or more double bonds, resulting in a bent or kinked chain.

Question 5

What is the primary function of proteins in living organisms?

Answer 5

Proteins have various functions, including acting as enzymes, structural components, transport molecules, and signalling molecules.

Question 6

Describe the structure of an amino acid.

Answer 6

An amino acid consists of an amino group (-NH₂), a carboxyl group (-COOH), and a variable side chain (R group) attached to a central carbon atom.

Question 7

Name the two types of nucleic acids and their respective functions.

Answer 7

The two types of nucleic acids are DNA (deoxyribonucleic acid), which carries genetic information, and RNA (ribonucleic acid), which plays a role in protein synthesis.

Question 8

What is the primary structure of a protein?

Answer 8

The primary structure of a protein refers to the linear sequence of amino acids in a polypeptide chain.

Question 9

Define the term “denaturation” in relation to proteins.

Answer 9

Denaturation is the process of altering the structure of a protein, often due to changes in temperature, pH, or exposure to certain chemicals, resulting in loss of its biological activity.

Question 10

Explain the role of enzymes in biological reactions.

Answer 10

Enzymes are biological catalysts that increase the rate of chemical reactions by lowering the activation energy required for the reaction to occur.

Question 11

What is the structural difference between alpha and beta glucose?

Answer 11

The structural difference between alpha and beta glucose lies in the position of the hydroxyl group (-OH) attached to the first carbon atom. In alpha glucose, the hydroxyl group is below the ring structure, while in beta glucose, it is above the ring structure.

Question 12

What is the function of cellulose in plants?

Answer 12

Cellulose provides structural support to plant cells and is the main component of the cell wall.

Question 13

Define the term “monomer” in the context of biological molecules.

Answer 13

A monomer is a small molecule that can chemically bond with other monomers to form a larger polymer.

Question 14

What is the role of triglycerides in the human body?

Answer 14

Triglycerides serve as a long-term energy storage molecule in the human body and provide insulation and protection to organs.

Question 15

Explain the difference between DNA and RNA.

Answer 15

DNA is a double-stranded nucleic acid that carries genetic information, while RNA is a single-stranded nucleic acid involved in protein synthesis and other cellular processes.

Question 16

What is the primary structure of nucleic acids?

Answer 16

The primary structure of nucleic acids refers to the sequence of nucleotides along the DNA or RNA molecule.

Question 17

Describe the role of chaperone proteins.

Answer 17

Chaperone proteins assist in the folding and unfolding of other proteins, ensuring their proper three-dimensional structure and preventing the formation of protein aggregates.

Question 18

What is the importance of hydrogen bonds in the structure of DNA?

Answer 18

Hydrogen bonds between complementary base pairs (adenine-thymine and cytosine-guanine) hold the two strands of DNA together, forming the double helix structure.

Question 19

What is the function of ATP (adenosine triphosphate) in cells?

Answer 19

ATP serves as the primary energy currency in cells, providing energy for cellular processes such as muscle contraction, active transport, and synthesis of macromolecules.

Question 20

Explain the role of phospholipids in cell membranes.

Answer 20

Phospholipids form the lipid bilayer of cell membranes, creating a selectively permeable barrier that controls the movement of substances in and out of the cell.

Question 21

What is the difference between starch and glycogen in terms of structure and function?

Answer 21

Starch is a polysaccharide found in plants, composed of amylose and amylopectin. Glycogen is a polysaccharide found in animals, consisting of highly branched chains. Starch serves as a storage molecule in plants, while glycogen serves as a storage molecule in animals, particularly in the liver and muscles.

Question 22

Describe the role of cofactors and coenzymes in enzyme catalysis.

Answer 22

Cofactors and coenzymes are non-protein molecules that assist enzymes in their catalytic activity. Cofactors can be inorganic ions, while coenzymes are small organic molecules. They often participate in chemical reactions by transferring functional groups or electrons.

Question 23

What is the difference between primary and secondary protein structure?

Answer 23

Primary protein structure refers to the linear sequence of amino acids in a polypeptide chain. Secondary protein structure refers to the folding of the polypeptide chain into regular structures such as alpha helices and beta sheets, stabilized by hydrogen bonding.

Question 24

Explain the role of water in hydrolysis and condensation reactions.

Answer 24

Water plays a crucial role in hydrolysis and condensation reactions. In hydrolysis, water is used to break bonds between monomers, leading to the breakdown of polymers into smaller units. In condensation reactions, water is released as a by-product when monomers join together to form a polymer.

Question 25

What is the importance of disulphide bridges in protein structure?

Answer 25

Disulphide bridges are covalent bonds formed between two cysteine amino acids. They contribute to the tertiary structure of proteins by creating strong cross-links, increasing protein stability and maintaining its three-dimensional shape.

Question 26

Describe the structure and function of phosphodiester bonds in nucleic acids.

Answer 26

Phosphodiester bonds connect nucleotides in nucleic acids. They are formed by a phosphate group bonding to the sugar (ribose or deoxyribose) of adjacent nucleotides. Phosphodiester bonds provide stability to the DNA or RNA molecule and allow for the formation of the polynucleotide chain.

Question 27

What is the role of antioxidants in cellular metabolism?

Answer 27

Antioxidants are molecules that help neutralize harmful free radicals generated during cellular metabolism. They protect cells from oxidative damage, which is linked to various diseases and aging processes.

Question 28

Define the term “quaternary structure” in relation to protein organization.

Answer 28

Quaternary structure refers to the arrangement of multiple polypeptide chains (subunits) in a protein complex. These subunits can be identical or different and interact with each other, contributing to the overall structure and function of the protein.

Question 29

Discuss the significance of pH in enzyme activity.

Answer 29

Enzyme activity is highly influenced by pH. Each enzyme has an optimum pH at which it functions most effectively. Deviations from the optimum pH can denature the enzyme, affecting its shape and ability to catalyse reactions.

Question 30

Explain the concept of substrate specificity in enzymes.

Answer 30

Substrate specificity refers to the ability of an enzyme to selectively bind to a specific substrate. The active site of an enzyme is complementary in shape and chemistry to its substrate, allowing for precise and efficient catalysis.

Question 31

What is the role of RNA polymerase in transcription?

Answer 31

RNA polymerase is an enzyme responsible for synthesizing RNA from a DNA template during transcription. It binds to the promoter region of a gene and catalyses the formation of phosphodiester bonds between ribonucleotides, resulting in the formation of an RNA molecule.

Question 32

Describe the structure and function of phospholipids in cell membranes.

Answer 32

Phospholipids have a hydrophilic head composed of a phosphate group and a glycerol molecule, and hydrophobic tails composed of fatty acid chains. In cell membranes, phospholipids arrange in a bilayer with their hydrophilic heads facing outward and their hydrophobic tails facing inward, forming a selectively permeable barrier that separates the cell from its environment.

Question 33

Explain the process of DNA replication.

Answer 33

DNA replication is the process by which a DNA molecule is copied to produce two identical daughter DNA molecules. It involves the separation of the DNA strands, the assembly of complementary nucleotides to each template strand, and the formation of phosphodiester bonds to create new DNA strands.

Question 34

Discuss the importance of ATP as an energy currency in cells.

Answer 34

ATP (adenosine triphosphate) is the primary energy currency in cells. It stores and transfers energy within the cell, providing the necessary energy for various cellular processes such as active transport, biosynthesis, and muscle contraction. ATP releases energy when a phosphate group is removed through hydrolysis, converting it to ADP (adenosine diphosphate) and inorganic phosphate.

Question 35

Define the term “competitive inhibition” in enzymology.

Answer 35

Competitive inhibition occurs when a molecule (the inhibitor) competes with the substrate for binding to the active site of an enzyme. The inhibitor binds reversibly to the active site, blocking the substrate from binding, and thus reducing the enzyme’s activity.

Question 36

Discuss the role of hydrogen bonding in the properties of water.

Answer 36

Hydrogen bonding between water molecules contributes to several of water’s unique properties. It gives water a high boiling point, a high specific heat capacity, and a high heat of vaporization. Hydrogen bonding also leads to the cohesive nature of water and its ability to form surface tension.

Question 37

Explain the significance of DNA supercoiling.

Answer 37

DNA supercoiling refers to the coiling and twisting of the DNA molecule upon itself. It is important for the compaction of DNA into the cell nucleus and plays a role in gene regulation, as supercoiling affects the accessibility of DNA to transcription factors and RNA polymerase.

Question 38

Describe the role of carbohydrates as structural components in living organisms.

Answer 38

Carbohydrates play a crucial role as structural components in living organisms. For example, cellulose forms the cell wall in plants, chitin forms the exoskeleton of insects, and peptidoglycan is found in bacterial cell walls.

Question 39

Discuss the significance of denaturation in relation to protein structure and function.

Answer 39

Denaturation refers to the disruption of a protein’s three-dimensional structure, leading to loss of its biological activity. Factors such as heat, extreme pH, and high salt concentrations can cause denaturation. Denaturation affects the protein’s shape, and since the function of a protein is often closely tied to its shape, denaturation can result in loss of function.

Question 40

Explain the concept of enzyme specificity.

Answer 40

Enzyme specificity refers to the ability of an enzyme to recognize and bind to a specific substrate or group of substrates. This specificity is due to the complementary shape and chemical properties of the enzyme’s active site and the substrate. Enzymes are highly specific, typically catalysing a particular reaction or set of related reactions.

Question 41

Describe the structure and function of haemoglobin.

Answer 41

Haemoglobin is a protein found in red blood cells that is responsible for carrying oxygen throughout the body. It consists of four polypeptide chains (two alpha and two beta chains) that are each associated with a heme group, which binds to oxygen.

Question 42

Explain the concept of enzyme-substrate specificity.

Answer 42

Enzyme-substrate specificity refers to the ability of an enzyme to bind to a specific substrate or group of substrates due to the complementary shape and chemical properties of their respective active sites. This specificity ensures that enzymes catalyse specific reactions and do not interact with unrelated molecules.

Question 43

Discuss the role of carbohydrates in energy storage.

Answer 43

Carbohydrates, such as glycogen in animals and starch in plants, serve as energy storage molecules. They are compact and readily available sources of glucose that can be broken down through hydrolysis to release energy for cellular processes.

Question 44

What are the primary components of a nucleotide?

Answer 44

A nucleotide consists of three components: a pentose sugar (either ribose or deoxyribose), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, guanine, or uracil). These components form the building blocks of nucleic acids, DNA, and RNA.

Question 45

Explain the role of covalent and hydrogen bonds in maintaining protein structure.

Answer 45

Covalent bonds, such as peptide bonds, form between amino acids to create the primary structure of a protein. Hydrogen bonds, on the other hand, contribute to the secondary, tertiary, and Quaternary structures of proteins, helping to stabilize the folding and interactions between different regions of the protein.

Question 46

Discuss the importance of water as a solvent in biological systems.

Answer 46

Water is an excellent solvent due to its polarity. It is capable of dissolving a wide range of polar and ionic substances, facilitating chemical reactions, transport of nutrients, and waste removal in biological systems.

Question 47

What is the function of RNA polymerase in gene expression?

Answer 47

RNA polymerase is responsible for transcribing DNA into RNA during gene expression. It binds to the DNA template strand and catalyses the synthesis of a complementary RNA molecule using ribonucleotides.

Question 48

Define the term “activation energy” in relation to enzyme-catalysed reactions.

Answer 48

Activation energy is the energy required for a chemical reaction to occur. Enzymes lower the activation energy, allowing reactions to proceed more readily by providing an alternative pathway with a lower energy barrier.

Question 49

Describe the structure and function of phosphodiester bonds in nucleic acids.

Answer 49

Phosphodiester bonds are formed between the phosphate group of one nucleotide and the sugar group of the adjacent nucleotide in a nucleic acid chain. They create a backbone of alternating phosphate and sugar molecules, providing stability and linking the nucleotides together.

Question 50

Discuss the role of lipids in insulation and waterproofing.

Answer 50

Lipids, such as adipose tissue (fat), serve as insulation in animals, providing thermal regulation and protection against temperature changes. Lipids, particularly waxes, also contribute to waterproofing in organisms, preventing excessive water loss and maintaining hydration.