Biology Chapter on Lipids and Nucleotides

Macromolecules

• Macromolecules are large, complex molecules crucial for life
• They are formed by linking smaller, simple molecules called monomers
• Polymers are large molecules formed from many monomers
• Four main types of macromolecules are found in organisms: carbohydrates, lipids, nucleic acids, and proteins

Carbohydrates

• Used for short-term energy storage
• Include starch, glycogen, cellulose, chitin, and sugars like glucose
• Used for quick energy, energy storage, and structural support
• Monomer: simple sugar
• Composed of carbon (C), hydrogen (H), and oxygen (O) in a 1:2:1 ratio
• Examples include glucose (C₆H₁₂O₆), fructose, and cellulose
• Classified as monosaccharides (one sugar), disaccharides (two sugars), and polysaccharides (many sugars)

Lipids

• Used by cells for long-term energy storage
• Constructed primarily from carbon and hydrogen
• Other uses include forming cell membranes, cushioning organs, and insulating the body (e.g., whale blubber)
• Examples: fats, oils, waxes, grease, steroids
• Monomers: glycerol and fatty acids
• Fats and oils are two types of lipids
• Saturated fats: found in animal products, solid at room temperature
• Unsaturated fats (oils): found in plant products, liquid at room temperature
• Phospholipids: crucial components of cell membranes, with polar heads and nonpolar tails

Nucleic Acids

• Monomer: nucleotide
• Composed of nitrogen (N), phosphorus (P), carbon (C), hydrogen (H), and oxygen (O)
• Large molecules that contain instructions (genetic information) to make proteins
• Two major types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
• DNA stores genetic information
• RNA carries genetic information
• Nucleotide structure includes a phosphate group, a sugar (DNA: deoxyribose; RNA: ribose), and a nitrogen base (adenine, guanine, cytosine, thymine, and uracil)

Proteins

• Monomer: amino acids
• Composed of carbon (C), oxygen (O), hydrogen (H), and nitrogen (N)
• Serve numerous functions, including movement (muscles), structural support (hair, fingernails, skin, claws), and acting as enzymes
• Made from combinations of 20 different amino acids
• Amino acids are linked by peptide bonds to form polypeptide chains, which fold into complex three-dimensional structures
• Different combinations of amino acids result in various protein structures and functions
• Enzymes are proteins that speed up chemical reactions by lowering activation energy
• Enzymes work on specific substrates and have an active site where substrates bind
• Enzyme names typically end in "-ase" (e.g., lactase, peptidase, lipase)
• Denatured proteins lose their shape, and hence, their function, due to factors such as temperature and pH changes

Chemical Bonding

• Chemical bonds are attractive forces between atoms or ions
• Bonds form when atoms share or transfer valence electrons
• Valence electrons are the electrons in the outermost energy level of an atom
• Three major types: covalent, ionic, and hydrogen bonds
• Covalent bonds: strong bonds formed by sharing electrons
• Hydrogen bonds: weak bonds formed by the attraction between a positively charged part of one molecule and a negatively charged part of another.
• Ionic bonds: strong bonds formed by the transfer of electrons, creating oppositely charged ions

Dehydration Synthesis

• Process where monomers combine to form polymers, with water as a byproduct.

Hydrolysis

• Process in which polymers are broken down into monomers, with water required to break the covalent bonds.