General Biology Study Guide: Chemistry, Biomolecules, and Cell Structure

Chapter 1: Introduction to Biology

Characteristics of Living Organisms

Biologists define life by a set of shared characteristics that distinguish living organisms from non-living objects.

• Order: Living things exhibit organized structure, often at multiple levels (cells, tissues, organs).

• Reproduction: Ability to produce new organisms, either sexually or asexually.

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

• Energy Processing: Living things obtain and use energy to power activities.

• Response to Environment: Ability to respond to stimuli.

• Regulation: Homeostasis, or maintaining stable internal conditions.

• Evolutionary Adaptation: Populations evolve over generations.

Levels of Biological Organization

Biological systems are organized from simple to complex levels:

• Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

Steps of the Scientific Process

The scientific method is a systematic approach to understanding the natural world.

• Observation

• Question

• Hypothesis

• Experiment

• Analysis

• Conclusion

Themes of Biology

Major themes include:

• Evolution

• Information Flow (genetic information)

• Energy Transformations

• Interactions within and between systems

Domains of Life

Life is classified into three domains:

• Bacteria

• Archaea

• Eukarya

Viruses are not classified as living organisms because they lack many characteristics of life (e.g., metabolism, cellular structure).

Chapter 2: Atoms, Chemistry, and Water

Physical Properties of Atoms

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

• Mass Number: Sum of protons and neutrons.

• Charge: Determined by the difference between protons and electrons.

Valence Electrons and Chemical Properties

Valence electrons are the outermost electrons and determine an atom's chemical reactivity.

• Atoms with full valence shells are generally inert (e.g., noble gases).

• Atoms tend to gain, lose, or share electrons to achieve stability.

Chemical Bonds

Atoms form bonds to achieve stable electron configurations.

• Covalent Bonds: Atoms share electrons (can be polar or non-polar).

• Hydrogen Bonds: Weak attractions between partially charged regions of molecules, especially in water.

• Ionic Bonds: Transfer of electrons from one atom to another, resulting in charged ions.

Water: Properties and Importance

Water is essential for life due to its unique properties:

• Cohesion and Adhesion: Water molecules stick to each other and to other surfaces.

• High Specific Heat: Water resists temperature changes.

• Solvent Abilities: Water dissolves many substances.

• Hydrogen Bonding: Responsible for many of water's properties.

Acids, Bases, and pH

Acids and bases affect the hydrogen ion concentration in solutions.

• Acid: Substance that increases H+ concentration.

• Base: Substance that decreases H+ concentration.

• pH Scale: Measures hydrogen ion concentration.

Formula:

$pH = -\log_{10}[H^+]$

Chapter 4: Organic Chemistry and Functional Groups

Importance of Valence Electrons (C, O, N, H)

Organic molecules are primarily composed of carbon, oxygen, nitrogen, and hydrogen. Their valence electrons determine bonding patterns and molecular shapes.

Isomers and Enantiomers

Isomers are molecules with the same molecular formula but different structures.

• Structural Isomers: Differ in the arrangement of atoms.

• Enantiomers: Mirror-image isomers, important in biological systems.

Functional Groups

Functional groups are specific groups of atoms within molecules that confer particular chemical properties.

• Hydroxyl (-OH)

• Carbonyl (C=O)

• Carboxyl (-COOH)

• Amino (-NH2)

• Sulfhydryl (-SH)

• Phosphate (-PO4)

• Methyl (-CH3)

Chapter 5: Biomolecules

Major Functional Groups in Biomolecules

Biomolecules contain functional groups that determine their properties and reactivity.

Condensation and Hydrolysis Reactions

Biological macromolecules are formed and broken down by specific reactions:

• Condensation (Dehydration Synthesis): Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Carbohydrates

Carbohydrates are energy sources and structural components.

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose).

• Polysaccharides: Long chains (e.g., starch, cellulose).

Lipids

Lipids include fats, phospholipids, and steroids.

• Fats: Energy storage.

• Phospholipids: Major component of cell membranes.

• Steroids: Hormones and membrane components.

Proteins

Proteins are polymers of amino acids and perform diverse functions.

• Primary Structure: Amino acid sequence.

• Secondary Structure: Hydrogen bonding (e.g., alpha helix, beta sheet).

• Tertiary Structure: 3D folding due to side chain interactions.

• Quaternary Structure: Multiple polypeptide chains.

Nucleic Acids

Nucleic acids (DNA, RNA) store and transmit genetic information.

• DNA: Deoxyribonucleic acid; double helix structure.

• RNA: Ribonucleic acid; single-stranded.

• Nucleotides: Composed of a sugar, phosphate group, and nitrogenous base.

• Bases: Purines (A, G) and Pyrimidines (C, T, U).

Table: Comparison of Biomolecule Types

Biomolecule	Monomer	Bond Type	Main Function
Carbohydrate	Monosaccharide	Glycosidic bond	Energy, structure
Lipid	Fatty acid, glycerol	Ester bond	Energy storage, membranes
Protein	Amino acid	Peptide bond	Catalysis, structure, transport
Nucleic Acid	Nucleotide	Phosphodiester bond	Genetic information

Additional Info

• Practice and review are essential for mastering biology concepts.

• Use study aids, ask questions, and compare notes for deeper understanding.

• Explore current research topics for broader context (e.g., climate change, water crisis).