Biomolecule

Biological Molecules Overview

Categories of Biomolecules

  • Carbohydrates

  • Proteins

  • Lipids

  • Nucleic Acids

BIOMOLECULE BUILDING BLOCKS

  • Biomolecules include:

    • Nucleic Acid

    • Carbohydrate

    • Lipid

    • Protein

Organic Molecules

  • Key Features of Carbon (C):

    • Always contains Carbon (C) and Hydrogen (H)

    • Carbon's electronic configuration (C-4):

    • Missing four electrons

    • Capable of forming 4 covalent bonds

    • Can bind with hydrogen, nitrogen, oxygen, and itself

    • Forms structures such as long chains, branched forms, and rings

Structure of Organic Molecules

  • Example - Glucose:

    • Chemical formula: $C6H{12}O_6$

Macromolecules vs. Monomers and Polymers

  • Macromolecules: Large molecules formed by the combination of many smaller units

    • Examples include:

    • Proteins

    • Carbohydrates

    • Lipids

    • DNA

  • Monomer: Simple molecules

    • Example: Monosaccharides, amino acids, nucleotides

  • Polymer: Large molecules formed by combining monomers

Chemical Reactions in Biomolecule Formation

  • Dehydration Synthesis:

    • Involves making big molecules from small molecules

    • A byproduct of this process is water

  • Hydrolysis:

    • Breaks big molecules into small molecules

    • Requires water

    • Water helps break up the bonds in molecules

    • Enzymes are required to facilitate this process

Carbohydrates Overview

  • Types of Carbohydrates:

    • Monosaccharides (e.g., glucose, sucrose, starch)

    • Short-chain sugars made up of 3-7 carbon atoms arranged in a ring

    • Only one unit molecule - monomer

    • Disaccharides:

    • Formed from two monosaccharides joined together

    • Examples include: Maltose (glucose + glucose), Lactose (glucose + galactose)

    • Polysaccharides:

    • Many monosaccharides linked together

    • Example:

      • Starch (glucose storage in plants)

      • Glycogen (glucose storage in animals)

      • Cellulose (found in plant cell walls)

Functions of Carbohydrates

  1. Short-term energy supply (e.g., glucose produces ATP energy)

  2. Short-term energy storage (e.g., glycogen stored in liver and muscles)

  3. Provide structural support (e.g., plant cell walls, insect exoskeletons)

  4. Serve as cell membrane markers (identity tags)

Properties of Monosaccharides

  • Presence of 3-7 carbon atoms in a ring structure

  • Example monosaccharides:

    • Glucose

    • Ribose

    • Galactose

    • Fructose

  • Specific terminology:

    • Pentose = 5 carbons (e.g., ribose)

    • Hexose = 6 carbons (e.g., glucose, galactose, fructose)

Structure and Formation of Disaccharides

  • Disaccharides Composition: Formed by dehydration synthesis

  • Example Reactions:

    • Maltose Formation:

    • C<em>6H</em>12O<em>6(glucose)+C</em>6H<em>12O</em>6(glucose)→C<em>12H</em>22O<em>11(maltose)+H</em>2OC<em>6H</em>{12}O<em>6 (glucose) + C</em>6H<em>{12}O</em>6 (glucose) \rightarrow C<em>{12}H</em>{22}O<em>{11} (maltose) + H</em>2O

Polysaccharides Overview

  • Repeating glucose subunits form polysaccharides:

    1. Starch

    • Glucose storage in plants, found in straight chains with little branching

    1. Glycogen

    • Glucose storage in animals, characterized by many side chains

    1. Cellulose

    • Provides structural integrity in plant cell walls, composed of β\beta-glucose

    • Linear molecule with alternating hydroxyl (-OH) positions

    • Indigestible by humans (considered fiber)

Starch Forms

  • Two major forms of starch:

    1. Amylose

    • Linked between carbons 1 and 4, free to twist, form coils

    1. Amylopectin

    • Linked between carbons 1 and 4, with branches between carbons 1 and 6

    • Branches extend in multiple directions

  • Glycogen features more frequent branching than amylopectin

Lipids Overview

  • Types of Lipids:

    1. Fatty Acids:

    • Chain of carbon atoms ending in the carboxyl group (COOH)

    • Saturated Fatty Acids: Solid at room temperature, potentially unhealthy

    • Unsaturated Fatty Acids: Liquid at room temperature, contain one or more double bonds

    1. Triglycerides: Glucose structure made of glycerol plus three fatty acids

    2. Phospholipids: Key component of cell membranes

    3. Steroids: Include ringed structures like cholesterol, important for signaling in the body

Functions of Lipids

  • Energy storage

  • Hormonal signaling

  • Structural component of cell membranes

Proteins Overview

  • Major Functions of Proteins:

    1. Structure: E.g., Keratin, collagen

    2. Movement: E.g., Actin and myosin

    3. Enzymes: Speeds up chemical reactions

    4. Transport: E.g., Hemoglobin carries oxygen in the blood

    5. Antibodies: Fight against disease

    6. Hormones: Maintain cell function (e.g., insulin)

Structure of Proteins

  • Made of amino acids:

    • Each consists of an amine group (NH3) and a carboxylic acid group (COOH)

    • 20 different amino acids exist with varying R groups

Amino Acids and Peptide Bonds

  • Dehydration synthesis creates:

    • Dipeptides: 2 amino acids

    • Polypeptides: Chains of ~3-20 amino acids

    • Proteins: Chains comprised of many amino acids

  • Peptide Bonds: Formed between carboxyl group of one amino acid and amino group of another

Levels of Protein Structure

  1. Primary Structure: Linear sequence of amino acids

  2. Secondary Structure: Hydrogen bonding forms alpha-helices and beta-sheets

    • Alpha-Helix: Right-handed coil structure

    • Beta-Sheet: Interlinked strands can be parallel or anti-parallel

  3. Tertiary Structure: 3D arrangement caused by bonding between R groups

  4. Quaternary Structure: Multiple polypeptide chains come together to form a single protein

Denaturation of Proteins

  • Proteins can lose their structure and function due to:

    • Changes in pH, temperature, chemicals, and heavy metals

    • Examples include heating an egg or adding vinegar to milk

Nucleic Acids Overview

  • Types:

    • DNA (Deoxyribonucleic Acid): Stores genetic information

    • Made of nucleotides (5 carbon sugar deoxyribose, phosphate, nitrogenous bases)

      • Bases include adenine (A), thymine (T), cytosine (C), guanine (G)

    • Contains a sugar-phosphate backbone, strands form a double helix

    • RNA (Ribonucleic Acid): Helps in protein synthesis

    • Made of nucleotides (5 carbon sugar ribose, phosphate, nitrogenous bases)

      • Bases include adenine (A), uracil (U), cytosine (C), guanine (G)

    • Typically single-stranded

Differences Between DNA and RNA

  • DNA:

    • Sugar: Deoxyribose

    • Strands: Double-stranded

    • Base: Contains thymine (T)

  • RNA:

    • Sugar: Ribose

    • Strands: Single-stranded

    • Base: Contains uracil (U) instead of thymine

ATP (Adenosine Triphosphate)

  • Primary molecule of energy

  • Energy is released during hydrolysis, breaking ATP into ADP and a phosphate group

  • Structure includes:

    • Sugar, Adenine, and 3 phosphates

Important Concepts to Remember

Nucleic Acids

  • Functions of DNA, RNA, and ATP

  • Structure of a nucleotide

  • Differences between DNA and RNA

Proteins

  • Functions

  • Formation of polypeptides

  • Four levels of structure and interactions that maintain them

  • Process of denaturation

Experiment Illustration - Protein Testing

  • Biuret's reagent used to test for proteins:

    • Typically performed by adding Biuret's reagent to a protein solution (e.g., egg albumin) and observing color changes indicating protein presence.