General Biology Study Guide: Chemistry of Life, Biomolecules, and Functional Groups

Chemistry of Life and Biological Organization

Characteristics of Living Organisms

Biologists use specific criteria to distinguish living organisms from non-living objects. Understanding these characteristics is foundational to the study of biology.

• Order: Living things exhibit organized structure, from molecules to cells to tissues.

• Reproduction: Ability to produce offspring, passing genetic material to the next generation.

• Growth and Development: Organisms grow and develop according to genetic instructions.

• Energy Utilization: Living things acquire and use energy for metabolism and activities.

• Response to Environment: Ability to sense and respond to stimuli.

• Homeostasis: Regulation of internal environment to maintain stable conditions.

• Evolutionary Adaptation: Populations evolve over generations.

Levels of Chemical/Biological Organization

Biological systems are organized hierarchically, from simple to complex:

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

Each level builds upon the previous, increasing in complexity and function.

Steps of the Scientific Process

The scientific method is a systematic approach to investigation:

• Observation

• Question

• Hypothesis

• Experimentation

• Data Collection

• Analysis

• Conclusion

Example: Testing the effect of light on plant growth.

Themes of Biology

Major themes include:

• Evolution

• Structure and Function

• Information Flow

• Energy Transformations

• Systems Biology

Domains of Life

Life is classified into three domains:

• Bacteria: Prokaryotic, unicellular organisms.

• Archaea: Prokaryotic, often extremophiles.

• Eukarya: Eukaryotic, includes plants, animals, fungi, and protists.

Viruses

Viruses share some characteristics with living things but lack others:

• Shared: Genetic material, ability to evolve.

• Lacking: Cellular structure, independent metabolism, reproduction outside host.

Atoms, Chemistry, and Water

Physical Properties of Atoms

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

• Mass and Charge: Protons (+), Neutrons (0), Electrons (-).

• Atomic Number: Number of protons.

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

Valence Electrons and Chemical Properties

Valence electrons determine an atom's chemical reactivity and bonding behavior.

• Octet Rule: Atoms tend to fill their outer shell with 8 electrons.

• Example: Carbon has 4 valence electrons, allowing it to form 4 covalent bonds.

Chemical Bonds

Atoms combine via chemical bonds:

• Covalent Bonds: Sharing of electron pairs (can be polar or non-polar).

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

• Ionic Bonds: Transfer of electrons, forming 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: Dissolves many substances.

• pH: Measure of hydrogen ion concentration. $pH = -\log[H^+]$

• Acids and Bases: Acids donate H+, bases accept H+.

Organic Chemistry and Functional Groups

Miller-Urey Experiment

The Miller-Urey experiment demonstrated that organic molecules could form under prebiotic Earth conditions.

• Setup: Simulated early Earth atmosphere, electrical sparks.

• Result: Formation of amino acids and other organic compounds.

Valence Electrons in Carbon

Carbon has four valence electrons, allowing it to form diverse and stable covalent bonds.

• Tetrahedral Geometry: Carbon forms four single bonds in a tetrahedral arrangement.

• Versatility: Basis for organic molecules.

Isomers and Enantiomers

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

• Structural Isomers: Differ in covalent arrangement.

• Cis-Trans Isomers: Differ in spatial arrangement around double bonds.

• Enantiomers: Mirror-image isomers, important in biology (e.g., amino acids).

Functional Groups

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

• Hydroxyl (-OH): Alcohols, polar.

• Carbonyl (C=O): Aldehydes and ketones.

• Carboxyl (-COOH): Acids, donates H+.

• Amino (-NH2): Bases, accepts H+.

• Sulfhydryl (-SH): Thiols, forms disulfide bonds.

• Phosphate (-PO4): Energy transfer (ATP).

• Methyl (-CH3): Non-polar, affects gene expression.

Biomolecules: Structure and Function

Major Functional Groups in Biomolecules

Biomolecules contain functional groups that determine their properties and reactivity.

• Carbohydrates: Contain hydroxyl and carbonyl groups.

• Lipids: Contain carboxyl and methyl groups.

• Proteins: Contain amino and carboxyl groups.

• Nucleic Acids: Contain phosphate, amino, and carbonyl groups.

Condensation and Hydrolysis Reactions

Biomolecules are assembled 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).

• Glycosidic Bond: Covalent bond joining sugars.

Lipids

Lipids include fats, phospholipids, and steroids.

• Fats: Energy storage, composed of glycerol and fatty acids.

• Phospholipids: Major component of cell membranes.

• Steroids: Hormones and membrane components.

Proteins

Proteins are polymers of amino acids, with diverse functions.

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Alpha helices and beta sheets (hydrogen bonds).

• Tertiary Structure: 3D folding (R-group interactions).

• Quaternary Structure: Multiple polypeptide chains.

• Peptide Bond: Covalent bond between amino acids.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA: Deoxyribonucleic acid, double helix.

• RNA: Ribonucleic acid, single-stranded.

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

• Phosphodiester Bond: Links nucleotides.

• Sugars: Ribose (RNA), Deoxyribose (DNA).

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

Table: Functional Groups and Their Properties

Functional Group	Structure	Properties	Example
Hydroxyl	-OH	Polar, forms hydrogen bonds	Alcohols (e.g., ethanol)
Carbonyl	C=O	Polar, reactive	Aldehydes, ketones
Carboxyl	-COOH	Acidic, donates H+	Amino acids, fatty acids
Amino	-NH2	Basic, accepts H+	Amino acids
Sulfhydryl	-SH	Forms disulfide bonds	Thiols
Phosphate	-PO4	Negative charge, energy transfer	ATP, nucleic acids
Methyl	-CH3	Non-polar, gene regulation	Methylated DNA

Study Strategies

• Use resources such as the BRC, study areas, and online videos.

• Practice with questions, drawings, and summaries.

• Compare and contrast concepts to deepen understanding.

• Review class recordings and notes regularly.

Additional info: Some content was inferred and expanded for clarity and completeness, including definitions, examples, and the table of functional groups.