Organic Molecules in Chemistry

Bulk Elements and Organic Molecules

Organic chemistry focuses on molecules primarily composed of carbon and hydrogen, often with oxygen, nitrogen, phosphorus, and sulfur (CHNOPS). These elements are fundamental to living systems.

• Carbon is the main component of organic molecules such as carbohydrates, proteins, nucleic acids, and lipids.

• Organic molecules are defined as molecules with covalently linked carbon atoms.

• Hydrocarbons are organic molecules made only of carbon and hydrogen atoms.

Example: Identifying organic molecules involves recognizing the presence of carbon backbones and hydrogen atoms.

Carbon as a Building Block

Carbon's ability to form four covalent bonds makes it a versatile 'atomic building block' for a wide variety of molecules.

• Carbon backbones can vary in length, position of double bonds, branch points, and linear vs. ring forms.

Example: Variations in carbon backbone structure allow for the diversity of organic molecules.

Functional Groups in Organic Chemistry

Definition and Importance

Functional groups are specific groups of atoms within molecules that are responsible for characteristic chemical reactions. They are commonly found attached to the carbon backbone and are reactive sites in organic molecules.

• Functional groups typically extend off the carbon backbone.

• Common functional groups in biology include hydroxyl, carboxyl, amino, sulfhydryl, methyl, phosphate, and carbonyl groups.

Example: Identifying functional groups in molecular structures is essential for predicting chemical reactivity.

Biomolecules: Classes and Structure

Major Classes of Biomolecules

Biomolecules are organic molecules essential for life. There are four primary classes:

1. Carbohydrates

2. Proteins

3. Nucleic Acids

4. Lipids

Each class has unique monomers and polymers, which determine their structure and function.

Monomers and Polymers

Monomers are individual building blocks that can be linked together to form polymers, which are long chains of monomers.

• Carbohydrates: Monosaccharides (e.g., glucose)

• Proteins: Amino acids

• Nucleic Acids: Nucleotides

• Lipids: Fatty acids and glycerol (not true polymers)

Polymer Formation and Breakdown

Polymers are formed and broken down by specific chemical reactions:

• Dehydration synthesis: Forms covalent bonds between monomers, releasing water ().

• Hydrolysis: Breaks covalent bonds by adding water, splitting polymers into monomers.

Example: Formation of maltose from two glucose molecules via dehydration synthesis.

Carbohydrates: Structure and Function

General Structure

Carbohydrates are carbon-based molecules hydrated with many hydroxyl groups (-OH). They are commonly referred to as sugars.

• General formula for simple carbohydrates:

• Monosaccharides are the simplest carbohydrates (e.g., glucose: )

Classification of Carbohydrates

Carbohydrates are classified by the number of monomer units:

1. Monosaccharides: Single sugar units (e.g., glucose)

2. Oligosaccharides: Short chains of covalently linked monosaccharides

3. Polysaccharides: Long chains of covalently linked monosaccharides (e.g., starch, cellulose, glycogen)

Formation and Breakdown of Polysaccharides

Polysaccharides are formed by dehydration synthesis, linking monosaccharides via glycosidic bonds. Hydrolysis breaks these bonds, releasing energy.

• Glycosidic bond: Covalent bond linking monosaccharides in polysaccharides.

• Dehydration synthesis:

• Hydrolysis:

Functions of Carbohydrates

Carbohydrates serve two main functions in living organisms:

1. Structural Support: Building materials for cell walls and exoskeletons (e.g., cellulose in plants, chitin in insects).

2. Energy Storage: Storage of energy in the form of polysaccharides (e.g., starch in plants, glycogen in animals).

Example: Starch is the main energy storage polysaccharide in plants, while glycogen serves this role in animals.

Summary Table: Key Terms and Concepts

Additional info: These notes provide foundational knowledge for understanding organic molecules and carbohydrates in general chemistry and introductory biochemistry courses.