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Introduction to Biomolecules

Biomolecules are organic compounds found within living organisms. They form the basis of all life processes and play crucial roles in various biological functions. Understanding biomolecules is essential for students pursuing degrees in biochemistry, molecular biology, and related fields.

Carbohydrates​

Carbohydrates are one of the most abundant biomolecules in nature. They serve as primary energy sources for cells and play key roles in cellular signaling and structural support.

Types of Carbohydrates​

  1. Monosaccharides (simple sugars):

    • Glucose, fructose, and galactose are common monosaccharides.
    • These simple sugars can be linked together to form more complex carbohydrates.

  2. Disaccharides:

    • Sucrose (table sugar) is composed of glucose and fructose molecules.
    • Lactose consists of glucose and galactose.

  3. Polysaccharides:

    • Starches (amylose and amylopectin) store energy in plants.
    • Glycogen serves as the main storage carbohydrate in animals.

  4. Oligosaccharides:

    • Short chains of 3-10 monosaccharide units.
    • Often involved in cell-cell recognition and adhesion.

Functions of Carbohydrates​

  • Energy storage and metabolism
  • Cell wall formation in bacteria and fungi
  • Structural components in plants (cellulose)
  • Signaling molecules in animal cells

Proteins​

Proteins are large biomolecules made up of amino acids. They perform a vast array of functions in living organisms.

Structure of Proteins​

  1. Primary structure:

    • The sequence of amino acids in a protein chain.
    • Determined by the genetic code encoded in DNA.

  2. Secondary structure:

    • Localized structures formed by hydrogen bonding between amino acids.
    • Alpha helices and beta sheets are common secondary structures.

  3. Tertiary structure:

    • The overall three-dimensional shape of a folded protein.
    • Determines the protein's function and stability.

  4. Quaternary structure:

    • Applies to multi-subunit proteins.
    • Describes how individual polypeptide chains interact.

Protein Functions​

  • Enzymatic catalysis
  • Transport of molecules across cell membranes
  • Storage and release of nutrients
  • Defense against pathogens (antibodies)

Lipids​

Lipids are biomolecules that do not dissolve in water but are soluble in organic solvents. They play critical roles in energy storage and membrane structure.

Types of Lipids​

  1. Triglycerides:

    • Main component of body fat in humans.
    • Composed of glycerol and three fatty acid chains.

  2. Phospholipids:

    • Key components of cell membranes.
    • Form bilayer structures due to amphiphilic properties.

  3. Steroids:

    • Include cholesterol and sex hormones like testosterone and estrogen.
    • Have a four-ring structure and are derived from lanosterol.

Functions of Lipids​

  • Energy storage
  • Membrane structure and fluidity
  • Hormone synthesis and regulation
  • Fat-soluble vitamin transport

Nucleic Acids​

Nucleic acids are biomolecules responsible for storing and transmitting genetic information.

Structure of Nucleic Acids​

  1. DNA (Deoxyribonucleic Acid):

    • Double-stranded molecule consisting of nucleotides.
    • Each nucleotide contains a phosphate group, a sugar molecule (deoxyribose), and one of four nitrogenous bases (adenine, guanine, cytosine, or thymine).

  2. RNA (Ribonucleic Acid):

    • Single-stranded molecule similar to DNA.
    • Contains ribose instead of deoxyribose and uracil instead of thymine.

Functions of Nucleic Acids​

  • Genetic information storage and transmission
  • Protein synthesis through messenger RNA
  • Regulation of gene expression
  • Catalytic activity in some cases (ribozymes)

Conclusion​

Understanding biomolecules is fundamental to biochemistry and its applications in medicine, agriculture, and biotechnology. This introduction provides a foundation for further exploration of each biomolecule type and their roles in living systems. As students progress in their studies, they will delve deeper into the chemistry, biosynthesis, and metabolic pathways of these vital biomolecules.

For beginners, it's important to remember that while these biomolecules have distinct functions, they often work together in complex interactions within cells and organisms. Visualizing their structures and understanding their chemical properties can greatly aid in comprehending their roles in biological processes.

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Further reading: