Biomolecules Part 1 Recap

Learning Objectives

• Distinguish between dehydration reactions and hydrolysis reactions.

• Compare the structure and function of the three classes of carbohydrates: monosaccharides, disaccharides, and polysaccharides.

• Categorize common sugars into their respective classes.

• Compare the structure and function of major lipid types: triglycerides, phospholipids, and steroids.

Dehydration Synthesis and Hydrolysis

Overview

Dehydration synthesis and hydrolysis are fundamental chemical reactions in biological systems, responsible for building and breaking down macromolecules.

• Dehydration synthesis: A reaction in which two monomers are joined by removing a molecule of water, forming a covalent bond. This process builds larger molecules from smaller units.

• Hydrolysis: A reaction in which a molecule is split into two smaller units by the addition of water, breaking a covalent bond. This process breaks down polymers into monomers.

• Example: Formation and breakdown of sucrose:

  • Dehydration synthesis: Glucose + Fructose → Sucrose + H2O

  • Hydrolysis: Sucrose + H2O → Glucose + Fructose

Equation:

$\text{Monomer}_1 + \text{Monomer}_2 \xrightarrow{\text{Dehydration}} \text{Polymer} + H_2O$

$\text{Polymer} + H_2O \xrightarrow{\text{Hydrolysis}} \text{Monomer}_1 + \text{Monomer}_2$

Carbohydrates

Definition and General Properties

Carbohydrates are organic molecules that include sugars and starches, serving as a primary energy source for cells.

• Composed of carbon (C), hydrogen (H), and oxygen (O).

• Hydrogen and oxygen are typically in a 2:1 ratio.

• Three main classes:

  • Monosaccharides: Single sugar units; the monomers of carbohydrates.

  • Disaccharides: Composed of two monosaccharide units.

  • Polysaccharides: Long chains of monosaccharide units; polymers.

Carbohydrate Molecules Important to the Body

Monosaccharides

Monosaccharides are the simplest carbohydrates and serve as building blocks for more complex sugars.

• Hexose sugars (6 carbons): Glucose, Fructose, Galactose

• Pentose sugars (5 carbons): Deoxyribose, Ribose

• Function: Provide immediate energy for cellular processes.

• Example: Glucose is the primary fuel for most cells.

Disaccharides

Disaccharides are formed by joining two monosaccharides via dehydration synthesis.

• Sucrose = Glucose + Fructose

• Maltose = Glucose + Glucose

• Lactose = Galactose + Glucose

• Function: Serve as transportable or storage forms of energy.

• Example: Lactose is the main sugar in milk.

Polysaccharides

Polysaccharides are large, complex carbohydrates composed of many monosaccharide units.

• Starch: Storage form of glucose in plants.

• Glycogen: Storage form of glucose in animals.

• Cellulose: Structural component in plant cell walls; not digestible by humans.

• Function: Energy storage and structural support.

• Example: Glycogen is stored in liver and muscle cells.

Classification Table: Common Carbohydrates

Additional info: The notes also mention lipids (triglycerides, phospholipids, steroids) as a topic for comparison, but detailed content is not present in the provided images. For a complete study guide, include lipid structure and function in further notes.