Biomolecules are organic compounds that are vital for the growth, sustenance, and reproduction of living organisms. They include carbohydrates, proteins, nucleic acids, and lipids, all of which play crucial roles in the biochemical processes that sustain life. This chapter will cover the structure, classification, and functions of these biomolecules, providing a foundational understanding for NEET aspirants.
Carbohydrates are optically active polyhydroxy aldehydes or ketones or compounds that yield such structures upon hydrolysis. They are broadly classified into three groups:
Did You Know?
Glucose, a monosaccharide, is the most abundant organic compound on Earth.
Monosaccharides are further classified based on the number of carbon atoms and the functional group present:
Common Misconception:
Not all compounds fitting the general formula Cx(H2O)y are carbohydrates. For example, acetic acid fits this formula but is not a carbohydrate.
NEET Tip:
Remember the structure and function of key polysaccharides like starch and cellulose, as they are frequently tested in NEET.
Proteins are polymers of amino acids linked by peptide bonds. They are classified based on their shape and structure:
Proteins have four levels of structure:
Mnemonic:
"Proteins Have Several Structural Levels" (Primary, Helices/Sheets, Tertiary, Quaternary)
Denaturation involves the loss of protein structure and function due to changes in pH, temperature, or chemical exposure. This process disrupts secondary and tertiary structures but leaves the primary structure intact.
Real-life Application:
The coagulation of egg whites when boiled is a common example of protein denaturation.
Enzymes are biological catalysts that speed up biochemical reactions without being consumed. They are highly specific, acting only on specific substrates.
Enzymes lower the activation energy required for reactions. They bind substrates at their active sites, forming enzyme-substrate complexes that facilitate the reaction.
NEET Tip:
Understand the factors affecting enzyme activity, such as temperature, pH, and substrate concentration, as these concepts are crucial for NEET.
Nucleic acids are polymers of nucleotides, each consisting of a sugar, a phosphate group, and a nitrogenous base. They are classified into two types:
Did You Know?
The double-helix structure of DNA was discovered by James Watson and Francis Crick, earning them the Nobel Prize in 1962.
Vitamins are organic compounds required in small amounts for normal growth and health. They are classified based on their solubility:
Common Misconception:
Taking excess vitamins can be harmful. Vitamin supplements should be taken only under medical advice.
Describe the primary structure of proteins. Answer: The primary structure of proteins refers to the linear sequence of amino acids linked by peptide bonds in a polypeptide chain.
Explain the difference between DNA and RNA. Answer: DNA is a double-stranded molecule with deoxyribose sugar and bases adenine, guanine, cytosine, and thymine. RNA is a single-stranded molecule with ribose sugar and bases adenine, guanine, cytosine, and uracil.
What is denaturation of proteins? Provide an example. Answer: Denaturation is the process where a protein loses its native structure and function due to external factors like pH or temperature changes. An example is the coagulation of egg whites upon boiling.
List three functions of carbohydrates in living organisms. Answer:
What are the fat-soluble vitamins, and why are they important? Answer: Fat-soluble vitamins include A, D, E, and K. They are important for vision, bone health, antioxidant protection, and blood clotting, respectively.
Did You Know?
Vitamin D is often called the "sunshine vitamin" because the body can synthesize it upon exposure to sunlight.