Biomolecules Overview

Biomolecules

• Biomolecules are organic compounds made by cells of living organisms.
• Organic compounds are composed of one or more carbon and hydrogen atoms covalently bonded to other atoms.
• Macromolecules are large molecules.
• A polymer is a long molecule made of repeating monomer units.

Synthesis and Breakdown of Biomolecules

• Dehydration/condensation reaction: two or more monomers bond together through the loss of a water molecule.
• Hydrolysis reaction: the breakdown of molecules due to reaction with water.

Amphipathic Molecules

• Amphipathic molecules contain both hydrophobic and hydrophilic regions.
• Phospholipids are a type of amphipathic molecule.

ATP (Adenosine Triphosphate)

• ATP is a molecule that stores and releases energy.
• High-energy phosphoanhydride bonds store energy and release it when hydrolyzed.
• ATP is crucial for cellular activities through hydrolysis.

Four Classes of Biomolecules

• Nucleic acids: involved in genetic information storage, expression, and transmission.
• Proteins: polymers of amino acids involved in various functions (e.g., enzymes, structural, regulatory, transport, defensive).
• Carbohydrates: provide energy and structure.
• Lipids: important in energy storage, cellular membranes, and signaling.

Nucleic Acids

• Nucleic acids are responsible for storing, expressing, and transmitting genetic information.
• DNA is a double-stranded molecule.
• RNA is a single-stranded molecule.
• Polymers of nucleotides.

DNA structure

• X-ray diffraction reveals DNA's double helix structure.
• The central cross in X-ray diffraction pattern is diagnostic of the helical structure.
• The spacing of DNA is 3.4Å.

DNA and Nucleotides

• Nitrogenous bases form the rungs of the DNA ladder.
• In DNA, A pairs with T and G pairs with C.
• DNA strands run in opposite directions (antiparallel).
• Nucleotides are the monomers of nucleic acids.

Pentose Sugars

• Pentose sugars (deoxyribose and ribose) form the backbone of nucleic acids.

Phosphate Groups

• Phosphate groups link nucleotides together.

Nitrogenous Bases

• Purines (adenine and guanine) have a double-ring structure.
• Pyrimidines (cytosine, thymine, and uracil) have a single-ring structure.
• In RNA, uracil replaces thymine.

Nucleotides

• Nitrogenous base + sugar + phosphate group = nucleotide.

Amino Acids

• Amino acids form proteins.
• The respective side chains of amino acids give unique chemical properties to proteins.
• Essential amino acids cannot be synthesized by the body.

Polypeptides

• Polypeptides are chains of amino acids covalently linked by peptide bonds.

Protein Structure

• Primary structure: The linear sequence of amino acids.
• Secondary structure: Folding into α-helices or β-pleated sheets.
• Tertiary structure: The 3D structure of the polypeptide chain.
• Quaternary structure: The assembly of multiple polypeptide chains in a functional protein.

Protein Denaturation

• Protein structure can change due to environmental factors (pH, salt concentration, temperature).
• Denaturation leads to inactivation of proteins.

Protein Functions

• Proteins have diverse functions depending on their type, including enzymes, structural proteins, motility proteins, regulatory proteins, transport proteins, hormonal proteins, receptor proteins, and defensive proteins.

Sickle Cell Anemia

• Sickle-cell anemia is a genetic disorder caused by a change in the primary structure of hemoglobin.