General Biology I: Foundational Concepts and Chemistry of Life

Chapter 1: The Unifying Themes of Life

Organization: What is the hierarchy of life?

The hierarchy of life describes the levels of biological organization, from the smallest units to the most complex systems.

• Key Levels: Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

• Example: A human (organism) is made of organs, which are made of tissues, which are made of cells.

Genetic Information: Storage and Transmission

Genetic information is stored in DNA and transmitted from one generation to the next through reproduction.

• Central Dogma: DNA → RNA → Protein

• Inheritance: Genes are passed from parents to offspring.

Energy and Matter: Transfer and Transformation

All living organisms require energy and matter to survive, grow, and reproduce.

• Photosynthesis: Plants convert solar energy into chemical energy.

• Cellular Respiration: Organisms break down molecules to release energy.

Interactions: Molecular Level and Ecosystems

Interactions occur at all levels, from molecules within cells to organisms within ecosystems.

• Example: Predator-prey relationships, symbiosis, competition.

Evolution: What is it?

Evolution is the process by which populations of organisms change over generations through natural selection and genetic variation.

• Natural Selection: The mechanism proposed by Charles Darwin, where organisms better adapted to their environment tend to survive and reproduce.

• Scientific Method: A systematic approach to investigation involving observation, hypothesis formation, experimentation, and analysis.

• Variables: Independent (manipulated) and dependent (measured) variables in experiments.

Chapter 2: Matter and Chemistry of Life

Atoms: Definitions and Properties

Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

• Atomic Number: Number of protons in the nucleus.

• Atomic Mass: Sum of protons and neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Electron Shells: Energy levels where electrons reside.

Chemical Bonds

Chemical bonds hold atoms together in molecules and compounds.

• Covalent Bonds: Atoms share electrons.

• Polar Covalent Bonds: Unequal sharing of electrons, leading to partial charges.

• Ionic Bonds: Transfer of electrons from one atom to another, creating ions.

• Hydrogen Bonds: Weak attractions between polar molecules, important in water and DNA.

Chemical Reactions and Equilibrium

Chemical reactions involve the transformation of reactants into products. Equilibrium occurs when the forward and reverse reactions are balanced.

• General Equation:

$\text{Reactants} \rightleftharpoons \text{Products}$

• Example: Water formation: $2H_2 + O_2 \rightarrow 2H_2O$

Chapter 3: Water and Its Properties

Water as a Polar Molecule

Water is a polar molecule due to the unequal sharing of electrons between oxygen and hydrogen atoms, resulting in partial charges.

• Polarity: Leads to hydrogen bonding and unique properties.

Properties of Water

Water exhibits several important properties that support life.

• Cohesion: Water molecules stick together.

• Adhesion: Water molecules stick to other surfaces.

• Surface Tension: The surface of water resists external force.

• High Specific Heat: Water absorbs and retains heat, moderating temperature changes.

• Evaporative Cooling: As water evaporates, it removes heat from surfaces.

Solutions and Solubility

Solutions are homogeneous mixtures of solutes dissolved in solvents. Water is known as the universal solvent.

• Hydrophilic: Substances that dissolve in water.

• Hydrophobic: Substances that do not dissolve in water.

• Molarity: Concentration of solute in solution, measured in moles per liter.

Chapter 4: Organic Chemistry and Biological Molecules

Organic Chemistry: Definitions and Experiments

Organic chemistry is the study of carbon-containing compounds. Stanley Miller's experiment demonstrated the abiotic synthesis of organic molecules.

• Stanley Miller Experiment: Simulated early Earth conditions to produce amino acids.

Properties of Carbon

Carbon atoms can form diverse molecules due to their ability to make four covalent bonds.

• Valence of 4: Allows for complex structures like chains and rings.

• Hydrocarbons: Molecules composed only of carbon and hydrogen.

• Isomers: Compounds with the same formula but different structures.

Chemical Groups and Molecular Function

Functional groups are specific groups of atoms within molecules that determine their chemical properties and reactions.

• Common Functional Groups: Hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl.

• ATP (Adenosine Triphosphate): The primary energy carrier in cells.

Functional Group	Structure	Properties	Example Molecule
Hydroxyl	-OH	Polar, forms hydrogen bonds	Ethanol
Carboxyl	-COOH	Acidic, donates H+	Acetic acid
Amino	-NH2	Basic, accepts H+	Glycine
Phosphate	-PO4	Negative charge, energy transfer	ATP
Methyl	-CH3	Nonpolar, affects gene expression	Methylated DNA

Additional info: Expanded explanations and examples were added for clarity and completeness, including the table of functional groups and their properties.