Biomolecules Overview

Biomolecules

• Biomolecules are biological molecules produced by the living organism's cells
• They are crucial for life as they help organisms carry out basic biological processes like reproduction, growth, and sustenance
• Molecular Biology is the study of the structure and function of biological molecules
• Macromolecule is a "giant molecule"

Types of Biomolecules

• Carbohydrates
• Proteins
• Amino Acids
• Lipids
• Nucleic Acids

Carbohydrates

• Most abundant molecules of life
• Energy source
• Plants produce carbohydrates in abundance through photosynthesis
• Composed of carbon, hydrogen, and oxygen (CHO)
• Roles:
  • Energy source (e.g., glucose)
  • Energy storage (e.g., starch in plants, glycogen in animals)
  • Structural unit (e.g., cellulose in plant fiber, chitin in exoskeletons)
• Types:
  • Simple (monosaccharides and disaccharides)
  • Complex (oligosaccharides and polysaccharides)
    • Monosaccharides: building blocks of more complex carbohydrates (e.g., glucose, fructose, galactose)
    • Disaccharides: two monosaccharides combined (e.g., sucrose, lactose, maltose)
    • Oligosaccharides: complex carbohydrates consisting of three to ten monosaccharides combined (e.g., raffinose)
    • Polysaccharides: complex carbohydrates rich in vitamins, minerals, and fiber. (e.g., starch, glycogen, cellulose, chitin)

Proteins

• Building blocks of life
• Composed of carbon, hydrogen, oxygen, nitrogen, and some sulfur and phosphorus (CHONPS)
• Functions:
  • Antibodies: bind to specific foreign particles (e.g., viruses, bacteria) to protect the body
  • Messengers: transmit signals to coordinate biological processes between different cells, tissues, and organs
  • Transport/Storage: bind and carry atoms and small molecules within cells and throughout the body
  • Structural: necessary components of the body; provide support

Amino Acids

• Building blocks of protein
• Connected by peptide bonds to form long chains of protein
• 20 standard amino acids, 11 non-essential, and 9 essential

Enzymes

• Comprise most of the proteins in living cells
• Biological catalysts that increase the rate of metabolic reactions
• Enzyme functions are greatly influenced by the chain structure of the protein molecule
• Denaturation: change in chain structure (proteins) caused by heat, pressure, and acidity
• Factors affecting enzyme activity: temperature, pH concentration of enzyme and substrate, collision/contact between enzyme and substrate molecules
• Catalyst: speeds up the rate of a reaction without being changed or used up during it (they are reusable)
  • Different enzyme needed for almost every chemical reaction in the body
  • A single enzyme catalyzes thousands or more reactions per second
  • Enzyme names usually end in "-ase"
  • Each enzyme is a specific helper to a specific reaction
• The enzyme-substrate complex is formed when the substrate interacts with the active site
• The active site is specific to its substrate; it is typically a pocket or groove on the surface of the protein molecule
• Models of Enzyme Action:
• Lock and Key Model: Proposed by Emil Fischer in 1899, the active site of an enzyme bears a specific conformation that precisely complements the substrate, allowing the substrate to fit into the active site like a lock and key
• Induced Fit Model: Proposed by Daniel Koshland in 1958, the active site of an enzyme is not a precise fit for the substrate. Instead, when exposed to a substrate, the active site undergoes a structural change to improve binding.

Inhibitors

• Enzyme inhibitors are molecules that interact with an enzyme to prevent it from working normally (e.g., poisons, drugs)
• Types:
  • Competitive inhibitors: bind to the active site, preventing the substrate from binding
  • Non-competitive inhibitors: bind to a different site on the enzyme, causing changes that prevent the enzyme from catalyzing the reaction.

Lipids

• Largely hydrocarbons dissolving in nonpolar substances and having partial or complete insolubility in water
• Types:
  • Triglycerides: Body’s main energy reservoir, stores unused calories, composed of glycerol backbone and three fatty acids (Fats and Oils)
• Fats: saturated fatty acid molecules, solid at room temperature, obtained from animal sources
• Oils: unsaturated fatty acid molecules, liquid at room temperature, obtained from plant sources
  • Sphingolipids: complex lipids made of sphingosine linked to a complex polar head and a long fatty acid chain
  • Phospholipids: have a phosphate group replacing one of the fatty acids in a triglyceride, the basis of the phospholipid bilayer of all biological membranes, act as a barrier within the cell
  • Steroids: have similar solubility properties as lipids but are not fatty acids or esters, common basic structure is the steroid nucleus (e.g., gonane. cyclopentanoperhydrophenanthrene)
    • Steroids reduce redness and swelling (inflammation) and help with inflammatory conditions (e.g., asthma, eczema)
    • They also reduce the activity of the immune system, which is the body's defense against illness and infection
    • Examples of steroid hormones: testosterone (primary androgen), estrogen (promotes the development and maintenance of female characteristics), and cortisone (released in response to stress, decreases the body’s natural defensive response and reduces symptoms such as swelling and allergic-type reactions; acts as a precursor to cortisol and has anti-inflammatory properties)

Nucleic Acids

• Informational molecules that carry the code of life (blueprints for proteins), thus controlling the life of a cell
• Types:
  • DNA (deoxyribose nucleic acid): double helix shape, composed of deoxyribose, and nitrogenous bases
  • RNA (ribonucleic acid): single-stranded shape, composed of ribose and nitrogenous bases
• Nucleotides: building blocks of nucleic acids. Consists of pentose sugar (deoxyribose or ribose), phosphate, and nitrogen bases (adenine-thymine, guanine-cytosine)

Metabolic Pathways

• Sequence of chemical reactions occurring in a cell
• Enzymes work together
• Catabolic pathways (catabolism): breakdown or digestion of large molecules; release energy
• Anabolic pathways (anabolism): synthesis of larger molecules by combining smaller molecules; require energy
• Cofactors: chemical substances assisting many enzymes for chemical reaction (e.g. iron, manganese, zinc)
• Coenzymes: organic molecules acting as cofactors (e.g. NAD, FAD)

Enzyme Substrate Complex

• Combination when the active site interacts with the substrate
• Each enzyme has an active site
• Substrate is a reactant that binds to the active site of an enzyme