General Biology Study Guide: Foundations of Life, Biomolecules, and Cell Structure

Chapter 1: The Characteristics of Life

Section 1: Defining Life

All living organisms share several fundamental characteristics that distinguish them from non-living matter.

• Organization: Living things are organized into cells.

• Acquire materials and energy: Organisms require nutrients and energy to sustain life. Example: Humans eat food to obtain nutrients for building cells and energy.

• Homeostasis: The ability to maintain a stable internal environment.

• Response to stimuli: Organisms respond to changes in their environment.

• Reproduction and development: Organisms reproduce and pass genetic information to offspring. Example: DNA is passed from parent to offspring, ensuring continuity of life.

• Adaptation: Populations evolve over time, leading to diversity and survival advantages.

Section 2: Levels of Biological Organization

Life is organized into hierarchical levels, from atoms to the biosphere.

• Atoms → Molecules → Cells → Tissues → Organs → Organ Systems → Organism → Population → Community → Ecosystem → Biosphere

• Example: The human body is composed of cells, which form tissues, organs, and organ systems.

Section 3: Humans in the Biosphere

Humans are mammals and part of the biosphere, interacting with other organisms and the environment.

• Mammals: Have hair, mammary glands, and include humans, raccoons, seals, and more.

• Culture: Human culture is learned and passed down generations.

• Biosphere: The zone of life on Earth, including land, water, and atmosphere.

Chapter 2: Biomolecules

Section 1: Atoms and Molecules

Atoms are the basic units of matter, composed of subatomic particles.

• Subatomic particles: Proton: Positively charged Neutron: No charge Electron: Negatively charged

• Atomic number: Number of protons in the nucleus.

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

Section 2: Water and Its Properties

Water is essential for life and has unique properties due to its molecular structure.

• Polarity: Water is a polar molecule, with partial positive charges on hydrogen and a partial negative charge on oxygen.

• Hydrogen bonding: Water molecules form hydrogen bonds, leading to cohesion and adhesion.

• Hydrophilic vs. Hydrophobic: Hydrophilic substances interact with water; hydrophobic substances do not.

• Acids and Bases: Acids release hydrogen ions ($H^+$); bases accept them. pH scale: Measures acidity or basicity (0-14).

Section 3: Organic Molecules

Organic molecules are carbon-based and include carbohydrates, lipids, proteins, and nucleic acids.

• Carbohydrates: Provide energy and structural support. Example: Glucose ($C_6H_{12}O_6$)

• Lipids: Fats and oils, used for energy storage and insulation. Example: Triglycerides

• Proteins: Made of amino acids, perform structural and enzymatic functions. Example: Enzymes, hemoglobin

• Nucleic acids: DNA and RNA, store genetic information.

Section 4: Structure and Function of Biomolecules

Each class of biomolecule has a specific structure and function.

• Triglycerides: Composed of glycerol and three fatty acids; store energy.

• Phospholipids: Form cell membranes; have hydrophilic heads and hydrophobic tails.

• Proteins: Made of amino acids; structure determines function.

• Nucleic acids: DNA and RNA; DNA stores genetic information, RNA helps in protein synthesis.

Chapter 3: Cells

Section 1: Cell Theory

The cell theory is a fundamental concept in biology.

• All living things are made of cells.

• Cells arise only from pre-existing cells.

Section 2: Cell Structure and Function

Cells vary in size and structure, with specialized organelles performing distinct functions.

• Prokaryotic cells: Lack a nucleus; include bacteria and archaea.

• Eukaryotic cells: Have a nucleus and membrane-bound organelles; include plants, animals, fungi, and protists.

• Organelles: Specialized structures within cells, such as mitochondria, endoplasmic reticulum, and ribosomes.

Section 3: Plasma Membrane and Transport

The plasma membrane controls the movement of substances into and out of the cell.

• Structure: Composed of a phospholipid bilayer with embedded proteins.

• Passive transport: Movement of molecules from high to low concentration; no energy required.

• Active transport: Movement of molecules from low to high concentration; requires energy (ATP).

• Osmosis: Diffusion of water across a membrane.

Section 4: The Nucleus and Endomembrane System

The nucleus stores genetic information and coordinates cellular activities.

• Nucleus: Contains DNA and is the site of genetic information storage.

• Endomembrane system: Includes the endoplasmic reticulum and Golgi apparatus, which process and transport proteins.

Section 5: Energy and Metabolism

Cells require energy to perform work, which is obtained through metabolic pathways.

• ATP: The main energy currency of the cell. $ATP \rightarrow ADP + P_i$ (energy released)

• Enzymes: Biological catalysts that speed up chemical reactions.

• Aerobic respiration: Uses oxygen to generate energy.

• Anaerobic respiration: Generates energy without oxygen.

Additional info:

• Some context and examples were expanded for clarity and completeness.

• Key terms and processes were defined to ensure self-contained study notes.