Chapter 2 Bio101

Hydrolysis and Polymers

  • Hydrolysis

    • Definition: Hydrolysis is a type of chemical reaction that breaks polymers apart.

    • Mechanism: To digest or break down a polymer, enzymes break bonds between the monomers.

    • Requirement: A water molecule is necessary for the reaction to occur.

Carbohydrates

  • Definition: Carbohydrates include simple sugars and polysaccharides.

  • Monosaccharides: The simplest form of carbohydrates (simple sugars) that serve as the building blocks of larger carbohydrates.

    • Examples:

    • Ribose

    • Glucose

    • Fructose

Carbohydrates: Synthesis and Breakdown

  • Dehydration Synthesis: This process binds two monosaccharides together to form a disaccharide.

    • Example: Sucrose is a disaccharide.

  • Hydrolysis: This process separates disaccharides into monosaccharides.

Complex Carbohydrates

  • Polysaccharides: Long chains of carbohydrates.

    • Types:

    • Cellulose: Provides structural support in plant cell walls.

    • Starch: Serves as an energy storage molecule in plants.

    • Glycogen: Serves as an energy storage molecule in animals.

Proteins

  • Function: Proteins are referred to as the “workers” of cells because they perform various functions.

  • Roles of specific proteins:

    • Collagen: Creates cellular structures.

    • Actin & Myosin: Responsible for muscle contractions.

Composition of Proteins

  • Amino Acids: The monomers that make up proteins.

    • There are 20 different amino acids in nature, all having the same general structure.

Properties of Amino Acids

  • Each amino acid possesses unique chemical and physical properties determined by their R groups:

    • Categories of R groups:

    • Polar

    • Nonpolar

    • Charged

    • Size Variations: Small, medium, and bulky sizes exist.

Protein Synthesis and Breakdown

  • Dehydration Synthesis: Binds two amino acids to form a dipeptide.

    • Definition: A long chain of amino acids is termed a polypeptide.

  • Hydrolysis: This process separates dipeptides and polypeptides into individual amino acids.

Protein Structure

Polypeptide Folding

  • A chain of amino acids folds into a unique 3-dimensional shape to become a functional protein.

  • The function of a protein is reliant on its shape, referred to as its tertiary structure.

  • Denaturation: When proteins lose their shape, they become nonfunctional.

Structural Levels of Proteins

  • Primary Structure: The sequence of amino acids in a polypeptide.

  • Secondary Structure: Localized areas that form coils, sheets, or loops within a polypeptide (often stabilized by hydrogen bonds).

  • Tertiary Structure:

    • Definition: Overall shape of a single polypeptide.

  • Quaternary Structure:

    • Definition: The overall protein shape arising from interactions between multiple polypeptides.

    • Note: Only proteins with multiple polypeptides exhibit quaternary structure.

Nucleic Acids

  • Function: Nucleic acids are essential for carrying genetic information.

    • Include DNA and RNA.

    • The primary structure of proteins in a cell is dictated by nucleic acids.

Composition of Nucleic Acids

  • Monomers of Nucleic Acids: Nucleotides.

    • Components of a Nucleotide:

    • Phosphate group

    • Five-carbon sugar

    • Nitrogenous base

Nitrogenous Bases in Nucleotides

  • Types of Nitrogenous Bases: There are five different types in nucleotides.

    • Shared Bases: Adenine, Cytosine, Guanine are present in both DNA and RNA.

    • Unique Bases:

    • Only DNA includes Thymine.

    • Only RNA includes Uracil.

Nucleic Acids: Synthesis and Breakdown

  • Dehydration Synthesis: Binds two nucleotides together to form strands of DNA or RNA.

  • Hydrolysis: This process separates nucleic acids into individual nucleotides.

Lipids

  • Definition: A class of biomolecules that are diverse in structure and functional characteristics; all lipids are hydrophobic.

  • Composition: Unlike carbohydrates, proteins, and nucleic acids, lipids are not constructed from chains of monomers.

Classes of Lipids

  1. Triglycerides:

    • Describe: Energy-rich lipids necessary for long-term energy storage. These include fats and oils.

  2. Steroids:

    • Structure: Distinctive four-ring structure.

    • Importance: Regulate cell membrane fluidity and are precursors for sex hormones.

Triglycerides Structure

  • Formation: Triglycerides are formed from covalently bonding three fatty acid molecules to a glycerol molecule through dehydration synthesis.

  • Hydrolysis: Separates fatty acids from glycerol.

Types of Fatty Acids

  • Saturated Fatty Acids:

    • Definition: All carbons are fully bonded to four other atoms, resulting in a straight shape.

  • Unsaturated Fatty Acids:

    • Definition: Contain at least one double bond, causing a bent shape.

Properties of Saturation in Triglycerides

  • Saturation affects how triglycerides behave:

    • Bends in the structure of unsaturated fatty acids prevent close packing.

    • Thus, unsaturated fats (like oils) are liquids at room temperature.

Waxes

  • Definition: A class of lipids composed of fatty acids combined with alcohols.

  • Function: Waxes are particularly hydrophobic and form waterproof seals in nature, such as in the cuticle of leaves to prevent desiccation.

Steroids Continued

  • Examples: Cholesterol regulates animal cell membrane fluidity and is key in synthesizing many sex hormones.

The Chemistry of Life

  • Overview: The properties of the organic molecules comprising our cells are fundamentally determined by their atoms and chemical bonds.

  • Conclusion: The presence of these molecules is vital; without them, life’s processes would cease.