Basics of Organic Molecules

Carbon Atoms

• Carbon possesses 4 valence electrons, enabling it to form 4 covalent bonds.
• Common bonding partners for carbon include hydrogen, oxygen, and nitrogen.

Covalent Bonds

• Covalent bonds form through the sharing of electrons between atoms.
• Nonpolar bonds feature equal sharing of electrons (e.g., C-H bonds), while polar bonds involve unequal sharing, leading to partial charges (e.g., O-H bonds).

Molecular Interactions

• Hydrophobic molecules are nonpolar and do not interact well with water.
• Hydrophilic molecules are polar and interact well with water.

Chemical Reactions

• Hydrolysis is a reaction that breaks down molecules through the addition of water (e.g., during digestion).
• Dehydration synthesis builds molecules by removing water, often forming polymers.

Carbohydrates

• Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
• Types of Carbohydrates:
  • Monosaccharides: Simple sugars like glucose and fructose.
  • Disaccharides: Two monosaccharides linked, such as sucrose.
  • Polysaccharides: Long chains of monosaccharides, including starch, glycogen, and cellulose.

Functions of Carbohydrates

• Provide rapid energy, primarily through glucose.
• Serve as energy storage in the form of glycogen in animals and starch in plants.
• Cellulose acts as insoluble fiber aiding digestion.

Isomers

• Isomers are molecules with identical chemical formulas but different structures, such as glucose and fructose.

Hydrolysis and Dehydration Synthesis

• Biological molecules are often polymers made from repeating subunits called monomers.
• Dehydration synthesis connects monomers into polymers while releasing water.
• Hydrolysis breaks down polymers into monomers by adding water, effectively reversing dehydration synthesis.

Monosaccharides

• Basic carbohydrate building blocks, for example:
  • Glucose: Primary energy source.
  • Fructose: Found in fruits.
  • Galactose: Present in yogurt, less sweet than glucose or fructose.
  • Ribose: Important for DNA structure.

Disaccharides

• Formed by linking two monosaccharides via a dehydration reaction, resulting in the loss of a water molecule.
• Examples include:
  • Sucrose: Table sugar from glucose and fructose.
  • Lactose: Sugar in milk from galactose and glucose, which some individuals cannot digest due to low levels of lactase enzyme.

Polysaccharides

• Composed of two or more monosaccharides, functioning as storage or structural components in various organisms.