Document 9

Chapter 2 – The Chemistry of Life

Definition: A substance composed of only one type of atom that cannot be broken down into simpler substances with different properties.

Proton: Positive charge, located in the nucleus.
Neutron: No charge (neutral), located in the nucleus.
Electron: Negative charge, located in the electron cloud.
Atomic Number: The number of protons equals the atomic number.
Atomic Mass: Protons and neutrons weigh approximately 1 amu, and the total of protons and neutrons equals the atomic mass.
Isotopes: Atoms of the same element that differ in the number of neutrons, resulting in different atomic masses.

Molecule: Interaction between 2 or more atoms that can be identical (e.g., O2).
Compound: Interaction between 2 or more atoms from different elements (e.g., CO2).
Cation: Atoms with a positive charge (e.g., Na+).
Anion: Atoms with a negative charge (e.g., Cl-).

Definition: Transferring of electrons from one atom to another. The resulting positive and negative charged ions are attracted to one another.
- Example: NaCl (Na+ ... Cl-), KCl (K+ ... Cl-).

Nonpolar Covalent Bonds: Equal sharing of electrons (e.g., O2, CO2) - strongest bond.
Polar Covalent Bonds: Unequal sharing of electrons (e.g., H2O) - second strongest bond.
Hydrogen Bonds: Attraction between hydrogen bonded in one molecule and an electronegative atom in another (e.g., adjacent H2O molecules, DNA base pairs) - weakest bond.

Definition: The sum of all chemical reactions that occur in the body.
1. Anabolic Reactions: Endergonic reactions involving synthesis of larger molecules from smaller ones (e.g., combining amino acids to form protein).
2. Catabolic Reactions: Exergonic reactions involving decomposition of larger molecules into simpler ones (e.g., digestive enzymes breaking down starch).

Strong Polarity: Water dissolves a wide range of substances due to its polar covalent bonds.
High Heat Capacity: When heat is applied, hydrogen bonds break, absorbing heat energy without significantly increasing temperature.
High Heat of Vaporization: Evaporation of water from skin removes a lot of heat, functioning as a cooling mechanism.
Cohesion: Water molecules cling to one another because of hydrogen bonds, acting as an effective transport medium and lubricant.

Hydrophilic (e.g., salt) vs. Hydrophobic (e.g., vegetable oils).
Electrolytes: Ionic compounds dissociating into cations and anions (e.g., Acids HCl, Bases KOH).

Acidity and Basicity:
- 0 to < 7 is acidic (more H+ than OH-).
- 7 is neutral (H+ = OH-).
- 7 to 14 is basic/alkaline (more OH- than H+).

Dehydration Synthesis: Forming macromolecules (polymers) by joining subunits (monomers) through covalent bonding, usually removing water.

Primary Monosaccharides: Glucose, deoxyribose, galactose, ribose, fructose.
Disaccharides: Two monosaccharides combined (e.g., sucrose: glucose + fructose; maltose: glucose + glucose; lactose: glucose + galactose).
Molecular Formula: C6H12O6.
Glycogen: A polysaccharide composed of glucose monomers.

Basic Structure: H2N-C-COOH (R group varies)
- Amino Group: H2N.
- Carboxyl Group: COOH.

Primary Structure: Polypeptide chains.
Secondary Structure: Alpha helix and beta-pleated sheets (stabilized by hydrogen bonds).
Tertiary Structure: 3-D shape of polypeptide; determines function (e.g., globular, fibrous proteins).
Quaternary Structure: More than one polypeptide chain (e.g., hemoglobin).

Causes: Extreme heat and pH changes can denature proteins, altering their function.

Function: Biological catalysts that speed up reactions without being consumed, specific to substrates, lowering activation energy.