Biological Molecules: Proteins

• Biological molecules are essential for life, performing a wide range of functions, and participating in various biological processes.
• There are four major classes of biological molecules: proteins, nucleic acids, carbohydrates, and lipids.

Proteins

• Proteins are large, complex molecules playing critical roles in the body.
• Amino acids joined by peptide bonds form proteins.
• Proteins catalyze biochemical reactions via enzymes.
• Proteins transport molecules, such as hemoglobin.
• Proteins provide structural support, for example, collagen.
• Proteins regulate cellular processes, such as transcription factors.
• Proteins contribute to immune defense through antibodies.
• A protein's structure determines its function.
• Primary structure denotes the amino acid sequence.
• Secondary structure refers to local folding patterns like alpha helices and beta sheets.
• Tertiary structure is the overall 3D shape of a single protein molecule.
• Quaternary structure describes the arrangement of multiple protein subunits in a complex.
• Post-translational modifications can alter protein activity, localization, and interactions.
• Phosphorylation, glycosylation, and ubiquitination exemplify post-translational modifications.
• Proteins interact with other molecules, including proteins, nucleic acids, lipids, and small molecules, to perform their functions.
• Misfolded proteins can cause diseases like Alzheimer's and Parkinson's.

Nucleic Acids

• Nucleic acids are nucleotide polymers storing and transmitting genetic information.
• DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) constitute the two main types of nucleic acids.
• DNA serves as the genetic material in most organisms, providing instructions for cell construction and operation.
• RNA's roles in gene expression include mRNA carrying genetic information to ribosomes.
• tRNA transports amino acids to ribosomes during protein synthesis.
• rRNA acts as a ribosomal component.
• A sugar, a phosphate group, and a nitrogenous base compose nucleotides.
• DNA contains adenine (A), guanine (G), cytosine (C), and thymine (T).
• RNA contains adenine (A), guanine (G), cytosine (C), and uracil (U).
• DNA has a double helix structure, with strands connected by hydrogen bonds between complementary bases (A-T and G-C).
• RNA is typically single-stranded but can adopt complex structures.
• Nucleic acids participate in DNA replication, transcription, and translation.

Carbohydrates

• Carbohydrates are organic compounds of carbon, hydrogen, and oxygen.
• They function as a primary energy source for living organisms and serve structural roles.
• Monosaccharides (simple sugars) include glucose, fructose, and galactose.
• Disaccharides consist of two joined monosaccharides, such as sucrose (glucose + fructose) and lactose (glucose + galactose).
• Polysaccharides are long monosaccharide chains, including starch, glycogen, and cellulose.
• Starch is the main glucose storage form in plants.
• Glycogen is the main glucose storage form in animals.
• Cellulose is a key component of plant cell walls.
• Carbohydrates can be modified by adding molecules like phosphate or sulfate groups.
• Carbohydrates participate in cell signaling and cell-cell recognition.

Lipids

• Lipids encompass a diverse group of hydrophobic molecules, like fats, oils, phospholipids, and steroids.
• Primarily composed of carbon, hydrogen, and oxygen, lipids contain a smaller proportion of oxygen compared to carbohydrates.
• Lipids facilitate energy storage.
• Lipids provide insulation.
• Lipids protect organs.
• Lipids form cell membranes.
• Fats and oils are triglycerides, composed of glycerol and three fatty acids.
• Fatty acids can be saturated (single bonds only) or unsaturated (one or more double bonds).
• Phospholipids, with hydrophilic heads and hydrophobic tails, are major components of cell membranes, forming a bilayer.
• Steroids, like cholesterol and hormones (e.g., testosterone and estrogen), feature a four-ring structure.
• Lipids can be modified by adding phosphate or carbohydrate groups.
• Lipids participate in cell signaling and inflammation.

Biomolecular Interactions

• Biomolecular interactions occur between biological molecules, such as proteins, nucleic acids, carbohydrates, and lipids.
• These interactions are essential for all biological processes, including DNA replication.
• These interactions are essential for all biological processes, including transcription.
• These interactions are essential for all biological processes, including translation.
• These interactions are essential for all biological processes, including metabolism.
• These interactions are essential for all biological processes, including cell signaling.
• These interactions are essential for all biological processes, including the immune response.
• Hydrogen bonds govern biomolecular interactions.
• Ionic bonds govern biomolecular interactions.
• Van der Waals forces govern biomolecular interactions.
• Hydrophobic interactions govern biomolecular interactions.
• The shapes and chemical properties of interacting molecules determine the strength and specificity of biomolecular interactions.
• Interactions can be transient or stable, depending on their function.
• Enzymes bind to substrates through non-covalent interactions to catalyze biochemical reactions.
• Antibodies bind to antigens with high specificity to neutralize pathogens.
• Receptor proteins bind to signaling molecules to initiate cellular responses.
• Disruptions in biomolecular interactions can lead to various diseases.