unit two

ORGANIC MOLECULES

Organic molecules contain carbon, oxygen, sulfur, nitrogen, hydrogen, and phosphorus. The main types of organic molecules include:

  1. Carbohydrates

  2. Proteins

  3. Lipids

  4. Nucleic acids

A. Carbohydrates

Carbohydrates contain carbon, hydrogen, and oxygen, typically represented by the general formula Cx(H2O). They have a 2:1 ratio of hydrogen to oxygen.

  • Monosaccharides: Single carbohydrates with the general formula (CH2O)n (n > 3).

    • Glucose: Common carbohydrate

    • Amylose: Branched form of glucose

    • Amylopectin: Another branched form of glucose

    • Triose (C3H6O3): Used in cellular respiration and photosynthesis.

    • Pentose (C5H10O5): Example includes ribose (RNA nucleotide).

    • Hexose (C6H12O6): Includes glucose, fructose, and galactose.

  • Disaccharides: Formed when two monosaccharides join together via a glycosidic bond.

    • Maltose: Glucose + Glucose

    • Lactose: Glucose + Galactose

    • Sucrose: Glucose + Fructose

  • Polysaccharides: Polymers of disaccharides, serving as complex carbohydrates.

    • Starch: Food storage in plants.

    • Glycogen: Food storage in animals.

    • Murine: Structural component of bacterial cell walls.

    • Cellulose: Structural component of plant cell walls.

B. Lipids

Lipids contain carbon, hydrogen, and oxygen, are insoluble in water, and are hydrophobic. They are soluble in inorganic solvents and are categorized into:

  1. Oils: Liquid at room temperature.

  2. Fats: Solid at room temperature.

  • Fatty Acid: Contains carbon and a carboxyl group (COOH).

  • Glycerol: Contains 3 carbon atoms and 3 hydroxyl (OH) groups.

  • Phospholipids: Comprised of fatty acids and a carboxyl group.

  • Waxes: Comprised of fatty acids and alcohol.

  • Monoglycerides: Comprised of fatty acids and glycerol.

Types of Fatty Acids:

  • Saturated Fatty Acids: Have single bonds, more energetic due to higher hydrogen content.

  • Unsaturated Fatty Acids: Have double bonds, less energetic due to lower hydrogen content.

Uses of Lipids:

  • Source of heat and energy.

  • Aid in digestion through bile acids.

  • Involved in hormone synthesis.

  • Structural components of cell membranes (e.g. phospholipids and glycerol).

C. Proteins

Proteins contain oxygen, hydrogen, nitrogen, phosphorus, and sulfur. They are made up of amino acids.

Structure of Amino Acids:

  • Comprise a central carbon atom (α-carboxyl group), an amino group, and hydrogen.

  • Peptide Bond: A bond between amino acids and the carboxyl group.

Levels of Protein Structure:

  1. Primary: Linear sequence of amino acids.

  2. Secondary: Peptide chains folded into structures like α-helices or β-pleated sheets.

  3. Tertiary: Globular or compact shapes formed by folding.

  4. Quaternary: Complex proteins made of more than one polypeptide chain, held together by hydrophobic interactions, hydrogen, and ionic bonds.

Types of Proteins (Based on Function, Composition, Structure):

  • Fibrous Proteins: Have a tertiary structure; e.g. keratin.

  • Globular Proteins: Have a ball-like structure; e.g. receptors that respond to stimuli.

D. Nucleic Acids

Nucleic acids are polymers of nucleotides, which consist of three components:

  1. Phosphoric Acid: Found in all nucleotides (H3PO4).

  2. Pentose Sugar: Comes in two types: ribose (C5H10O5) and deoxyribose (C5H10O4).

  3. Organic N-Base: Divided into two groups:

    • Pyrimidines: Single rings with 5 and 6 sides.

    • Purines: Double rings with 5 and 6 sides.

Phosphodiester Bond:

  • The bond between nucleotides.

Types of Nucleic Acids:

  • DNA (Deoxyribonucleic Acid): Genetic formation of the cell.

  • RNA (Ribonucleic Acid): Vital for protein synthesis.

  • AMP (Adenosine Monophosphate): Coenzyme important in energy production.

  • ADP (Adenosine Diphosphate): Involved in cellular metabolic activities.

  • ATP (Adenosine Triphosphate): Key energy carrier for osmotic work and muscular contraction.

  • NAD (Nicotinamide Adenine Dinucleotide): An electron carrier important in respiration.

  • FAD (Flavin Adenine Dinucleotide): Another electron carrier important in respiration.

  • NADP (Nicotinamide Adenine Dinucleotide Phosphate): Involved in photosynthesis.

  • CoA (Coenzyme A): Important in respiration for transferring acetyl groups into the Krebs cycle.

Characteristics of RNA:

  • Pentose sugar is ribose.

  • Single polynucleotide chain.

  • Small molecular mass.

  • Contains adenine, guanine, cytosine, and uracil.

  • Varying A:U to C:G ratios.

  • Manufactured in the nucleus, found outside the cell.

  • Chemically less stable, temporary existence.

  • Has three basic forms: mRNA, tRNA, rRNA.

Characteristics of DNA:

  • Pentose sugar is deoxyribose.

  • Double polynucleotide chain.

  • Large molecular mass.

  • Contains adenine, guanine, cytosine, and thymine.

  • A:T to C:G ratios is one.

  • Found in the nucleus with a constant amount across cells (except agemates and spores).

  • Chemically stable and permanent with only one basic form.

INORGANIC MOLECULES

Inorganic molecules do not contain hydrogen and carbon.

BIOCHEMICAL SUBSTANCES

Substances derived from biological resources.

Water

Water is the most abundant element with several properties:

  • Liquid at room temperature.

  • High latent heat (requires high energy to heat).

  • High latent heat of vaporization and before fusion (freezing).

  • High surface tension and low viscosity.

Uses of Water Properties:

  • Important for living organisms due to temperature regulation.

  • Aids in cooling by evaporation.

  • Allows small animals to land on it.

  • Moves easily through small spaces (e.g. soil, root, cellular wall).

  • Acts as a universal solvent and participates in chemical reactions (e.g. hydrolysis).

Uses of Water in Plants:

  • Osmosis and turgidity.

  • Reagent in photosynthesis.

  • Transpiration and germination.

Uses of Water in Animals:

  • Blood transport.

  • Osmoregulation and cooling through evaporation.

  • Lubrication of joints and skeletal support.

  • Protection (tears, mucus).

Minerals and Salts

Components of both organic and inorganic molecules.

Major Elements:

  • Calcium (Ca): Strengthens bones and teeth, serves as fertilizer, forms shells of mollusks, and the middle lamina in plant cell walls.

  • Sulfur (S): Involved in protein synthesis (e.g. keratin) and the formation of organic compounds.

  • Nitrogen (N): Important for the synthesis of chlorophyll and nucleic acids.

  • Phosphorus (P): Needed for nucleic acids and phospholipids in cell membranes, important for bones and teeth.

  • Magnesium (Mg): Part of chlorophyll structure, cofactor for enzymes like ATPase.

  • Sodium (Na): Maintains electric potential across membranes, conducts nerve impulses, regulates osmotic balance, and serves as a cofactor in photosynthesis.

  • Potassium (K): Similar functions to sodium.

Trace Elements:

  • Iron (Fe): Functions in oxygen transport (hemoglobin), electron transfer (respiration, photosynthesis), and chlorophyll synthesis; deficiency can lead to anemia.

  • Manganese (Mn): Important for fatty acid fixation, enzyme functions in photosynthesis and respiration, and bone development.

  • Molybdenum (Mo): Essential for nitrogen fixation.

  • Copper (Cu): Plays a role in melanin production and electron transfer.

  • Iodine (I): Crucial for the hormone thyroxine; deficiency can lead to goiter.