General Biology: Foundations, Chemistry, and Macromolecules Study Guide

Introduction to Biology

What is Biology?

Biology is the scientific study of life and living organisms, encompassing their structure, function, growth, evolution, distribution, and taxonomy.

Characteristics of Life

• Organization: Living things are composed of one or more cells.

• Metabolism: They obtain and use energy.

• Homeostasis: They maintain a stable internal environment.

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

• Reproduction: They reproduce to pass on genetic information.

• Response to Stimuli: Organisms respond to environmental changes.

• Evolution: Populations evolve over generations.

Scientific Method

Steps of the Scientific Method

1. Observation

2. Question

3. Hypothesis formation

4. Experimentation

5. Data collection and analysis

6. Conclusion

7. Communication of results

Hypothesis vs. Theory

• Hypothesis: A testable, tentative explanation for an observation.

• Theory: A well-substantiated explanation of some aspect of the natural world, based on a body of evidence.

Levels of Biological Organization

• Atom

• Molecule

• Organelle

• Cell (smallest, most basic unit of life)

• Tissue

• Organ

• Organ system

• Organism

• Population

• Community

• Ecosystem

• Biosphere

Classification of Life

Three Domains of Life

• Bacteria

• Archaea

• Eukarya

Kingdoms

• Plantae: Contains photosynthetic organisms.

• Fungi: Example: Mushrooms, yeast.

• Animalia

• Protista

• Monera (Bacteria and Archaea)

Example:

• Amoeba: Belongs to the Kingdom Protista.

Genetics and Molecular Biology

DNA

• Definition: Deoxyribonucleic acid, the molecule that stores genetic information.

• Structure: Double helix composed of nucleotides (adenine, thymine, cytosine, guanine).

Genome vs. Proteome

• Genome: The complete set of genes or genetic material in an organism.

• Proteome: The entire set of proteins expressed by a genome.

Biological Chemistry

Atoms and Elements

• Atomic Number: Number of protons in an atom.

• Mass Number: Number of protons plus neutrons.

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

• Trace Elements: Elements required in minute amounts (e.g., iron, zinc).

• Mineral Elements: Essential elements such as calcium, potassium, sodium.

Subatomic Particles

• Proton: Positively charged particle in the nucleus.

• Neutron: Neutral particle in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

Electron Configuration

• Orbital: Region around the nucleus where electrons are likely to be found.

• Valence Electrons: Electrons in the outermost shell, important for chemical bonding.

• Octet Rule: Atoms tend to gain, lose, or share electrons to achieve eight electrons in their valence shell.

Chemical Bonds and Molecules

Types of Chemical Bonds

• Ionic Bond: Transfer of electrons from one atom to another (e.g., NaCl).

• Covalent Bond: Sharing of electron pairs between atoms (strongest bond).

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., water molecules).

Comparison of Chemical Bonds

Bond Type	Strength	Example
Covalent	Strongest	H2O
Ionic	Strong	NaCl
Hydrogen	Weakest	Between water molecules

Polar vs. Nonpolar Molecules

• Polar Molecule: Unequal sharing of electrons, resulting in partial charges (e.g., water).

• Nonpolar Molecule: Equal sharing of electrons, no partial charges (e.g., O2).

Compounds vs. Molecules

• Molecule: Two or more atoms held together by covalent bonds.

• Compound: Substance formed from two or more different elements chemically combined.

Properties of Water and Solutions

Hydrophilic vs. Hydrophobic

• Hydrophilic: Water-attracting substances (e.g., salts, sugars).

• Hydrophobic: Water-repelling substances (e.g., oils, fats).

Solvent, Solute, and Solution

• Solvent: Substance that dissolves another (e.g., water).

• Solute: Substance dissolved in a solvent (e.g., salt in water).

• Solution: Homogeneous mixture of solute and solvent.

pH Scale, Acids, and Bases

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic), with 7 as neutral.

• Acid: Substance that increases H+ concentration (e.g., HCl).

• Base: Substance that decreases H+ concentration (e.g., NaOH).

Organic Chemistry in Biology

Organic Molecules and Isomers

• Organic Molecule: Contains carbon atoms (e.g., glucose).

• Isomer: Compounds with the same molecular formula but different structures (e.g., glucose and fructose).

Chemical Functional Groups

• Hydroxyl (-OH)

• Carbonyl (C=O)

• Amino (-NH2)

• Methyl (-CH3)

Macromolecules

Four Major Macromolecules

• Carbohydrates

• Lipids

• Proteins

• Nucleic Acids

Carbohydrates

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

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

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

Lipids

• Examples: Fats, oils, phospholipids, steroids.

• Functions: Energy storage, membrane structure, signaling.

Proteins

• Examples: Enzymes, antibodies, hemoglobin.

• Functions: Catalysis, structure, transport, signaling, defense, movement, storage, regulation.

Nucleic Acids

• Examples: DNA, RNA.

• Functions: Store and transmit genetic information.

ATP (Adenosine Triphosphate)

• Definition: The primary energy carrier in cells.

• Structure: Adenine base, ribose sugar, three phosphate groups.

Dehydration and Hydrolysis Reactions

• Dehydration Reaction: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Denaturation

• Definition: Loss of protein's native structure due to external stress (e.g., heat, pH).

Summary Table: Macromolecules

Macromolecule	Monomer	Example	Main Function
Carbohydrate	Monosaccharide	Glucose, Starch	Energy, Structure
Lipid	Fatty acid, Glycerol	Triglyceride, Phospholipid	Energy storage, Membranes
Protein	Amino acid	Enzyme, Hemoglobin	Catalysis, Structure
Nucleic Acid	Nucleotide	DNA, RNA	Genetic information

Additional info:

• Some details, such as the 8 functions of proteins, are referenced from Campbell Biology and include: enzymatic, structural, storage, transport, hormonal, receptor, contractile/motor, and defensive functions.

• For more in-depth study, refer to figures and tables in standard biology textbooks such as Campbell Biology.