4. Organic and Inorganic Molecules

Organic Molecules: Molecules of life or from living things.
- Typically contain carbon, hydrogen, and oxygen.
- Carbon atoms form covalent bonds with other carbon atoms, as well as oxygen and hydrogen.
- Organic carbon-containing molecules use covalent bonds.
Inorganic Molecules: Molecules that make up non-living matter.
- Made by both covalent and ionic bonds but are often ionically bonded.
- Important for body functions but don't form structures.

Inorganic molecules that are soluble and dissociate into ions in water.
Covalently bonded substances do not dissociate in water, while ionically bonded substances do.
Ions allow for the movement of charge and create electrical current in solution.
Example: Sodium chloride (table salt) dissociates into $Cl^-$ and $Na^+$ ions in solution.
Glucose, a covalently bonded molecule, dissolves in water but does not conduct electricity because if it was ionically bonded it would dissociate. Because it is covalently bonded with no charge, then it is polar covalent.

Essential for electrical signaling in the body (e.g., muscles, nerves).
Help maintain the balance of solutes in body fluids, influencing water movement.
Charged ions do not interact with nonpolar molecules, affecting movement across barriers.
Maintaining proper electrolyte concentration is crucial for normal body function.

Slight increase in potassium concentration $[K^+]$ can lead to a weak, irregular heartbeat.
Slight decrease in potassium concentration $[K^+]$ can result in general muscular paralysis.

The body uses organ systems to manage electrolyte concentrations.
Electrolytes can be replenished through foods and drinks, especially after sweating or illness.
Electrolyte-rich drinks help restore normal function.

Carbohydrates
Lipids
Proteins
Nucleic Acids
High-Energy Compounds: ATP (adenosine triphosphate), which is a small molecule used to move energy within the cell.

Monosaccharides: Simple sugars (e.g., glucose, fructose).
Disaccharides: Two monosaccharides combined (e.g., lactose).
Polysaccharides: Many monosaccharides combined (e.g., glycogen).
- Monosaccharides can move easily around the body; complex carbs are harder to move because of their physical properties.

Repeating units of monosaccharides joined together by enzymes.
Enzymes also break down complex carbs (e.g., lactase breaks down lactose).
Understanding enzyme function helps explain conditions like lactose intolerance.

Structural support (e.g., collagen).
Enzymes (e.g., lactase).
Hormones (e.g., insulin).
Antibodies (immune defense).
Transport (e.g., hemoglobin carries oxygen, albumin carries a variety of solutes).

Long chains of amino acids; 10 are nonessential (made by the body), and 10 are essential (obtained from diet).
Each amino acid has different features (size, shape, charge).
The sequence of amino acids determines the protein's properties.

Primary Structure: Sequence of amino acids.
Secondary Structure: Folding of small amino acid sections based on charge and hydrophobicity.
Tertiary Structure: Interactions between amino acids further apart in the chain, influenced by the environment.
Quaternary Structure: Multiple subunits (individual peptides) interacting to form the final protein structure.

Protein shape (dictated by amino acids) determines its function.
Can be structural (part of the extracellular matrix) or functional (enzymes, transporters).
Enzymes speed up reactions by bringing components together (e.g., sucrase separating sucrose into glucose and fructose).
Transporters move substances across membranes.

Made of nucleotides, which include:
- Nitrogen-containing bases.
- Sugar-phosphate group (ribose sugar in DNA, slightly different in RNA).
Nucleotides form strands; DNA has two strands, while RNA has one.