General Biology: Core Concepts and Study Guide

Chapter 1: Introduction to Biology

What is Science?

Science is a systematic approach to understanding the natural world through observation, experimentation, and reasoning.

• Scientific Method: Involves making observations, forming hypotheses, conducting experiments, and drawing conclusions.

• Hypothesis: A testable statement that explains observations.

• Theory: A well-substantiated explanation of natural phenomena, supported by evidence.

Domains of Life

All living organisms are classified into three domains based on cellular organization and genetics.

• Bacteria: Single-celled prokaryotes with simple cell structure.

• Archaea: Single-celled prokaryotes, often found in extreme environments.

• Eukarya: Organisms with complex cells containing a nucleus (includes plants, animals, fungi, and protists).

Prokaryotes vs. Eukaryotes

• Prokaryotes: Lack a nucleus and membrane-bound organelles.

• Eukaryotes: Have a nucleus and membrane-bound organelles.

Evolution and Speciation

Evolution explains the unity and diversity of life. Natural selection is a key mechanism driving evolution and speciation.

• Natural Selection: Process where organisms better adapted to their environment tend to survive and reproduce.

• Speciation: Formation of new and distinct species in the course of evolution.

Chapter 2: Chemistry of Life

Atoms, Elements, Compounds, and Molecules

All matter is composed of atoms, which combine to form elements, compounds, and molecules.

• Atom: The smallest unit of an element, consisting of protons, neutrons, and electrons.

• Element: A substance made of only one kind of atom.

• Compound: A substance formed from two or more elements chemically bonded.

• Molecule: Two or more atoms bonded together.

Atomic Structure

• Protons: Positively charged particles in the nucleus.

• Neutrons: Neutral particles in the nucleus.

• Electrons: Negatively charged particles orbiting the nucleus.

Electronegativity and Chemical Bonds

Electronegativity differences between atoms determine the type of bond formed.

• Covalent Bonds: Atoms share electrons; can be polar (unequal sharing) or nonpolar (equal sharing).

• Ionic Bonds: Atoms transfer electrons, resulting in charged ions.

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

Polarity of Water

• Water Molecule: Polar due to unequal sharing of electrons between oxygen and hydrogen.

• Hydrogen Bonding: Responsible for water's unique properties, such as cohesion and high specific heat.

Example: Water's polarity allows it to dissolve many substances, making it an excellent solvent in biological systems.

Chapter 3: Water, Acids, and Bases

Properties of Water

Water's structure and hydrogen bonding give it unique properties essential for life.

• Cohesion: Water molecules stick together.

• Adhesion: Water molecules stick to other surfaces.

• High Specific Heat: Water resists temperature changes.

pH and Buffers

• pH Scale: Measures the concentration of hydrogen ions ($[H^+]$) in a solution.

• Acids: Substances that increase $[H^+]$ in solution.

• Bases: Substances that decrease $[H^+]$ in solution.

• Buffer: Substance that minimizes changes in pH.

Formula:

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

Example: Blood contains buffers to maintain a stable pH necessary for physiological processes.

Chapter 4: Organic Molecules and Macromolecules

Carbon and Organic Molecules

Carbon's versatility allows it to form a wide variety of organic molecules essential for life.

• Functional Groups: Specific groups of atoms that confer particular properties to organic molecules (e.g., hydroxyl, carboxyl, amino).

• Polymers: Large molecules made by joining smaller subunits (monomers).

• Monomers: Small molecules that serve as building blocks for polymers.

Major Classes of Biological Macromolecules

• Carbohydrates: Energy storage and structural support.

• Lipids: Energy storage, membrane structure, signaling.

• Proteins: Catalysis, structure, transport, signaling.

• Nucleic Acids: Information storage and transfer (DNA and RNA).

Example: Starch (a carbohydrate polymer) stores energy in plants; DNA (a nucleic acid polymer) stores genetic information.

Chapter 5: Proteins and Nucleic Acids

Proteins: Structure and Function

Proteins are polymers of amino acids and perform a wide range of functions in cells.

• Amino Acid Structure: Central carbon, amino group, carboxyl group, side chain (R group).

• Levels of Protein Structure:

  • Primary: Sequence of amino acids.

  • Secondary: Alpha helices and beta sheets formed by hydrogen bonding.

  • Tertiary: Overall 3D shape due to interactions among side chains.

  • Quaternary: Association of multiple polypeptide chains.

• Denaturation: Loss of protein structure and function due to environmental changes.

Nucleic Acids: DNA and RNA

Nucleic acids store and transmit genetic information.

• DNA: Double-stranded, stores genetic information.

• RNA: Single-stranded, involved in protein synthesis and gene regulation.

• Nucleotide: Monomer of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base.

Example: DNA replication ensures genetic continuity; RNA translates genetic code into proteins.

Chapter 5 Pt. 2: Carbohydrates and Lipids

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, and serve as energy sources and structural components.

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

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

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

Lipids

Lipids are hydrophobic molecules important for energy storage, membrane structure, and signaling.

• Triacylglycerol: Main form of energy storage in animals.

• Phospholipids: Major component of cell membranes.

• Steroids: Include hormones and cholesterol.

Type	Structure	Function
Triacylglycerol	Glycerol + 3 fatty acids	Energy storage
Phospholipid	Glycerol + 2 fatty acids + phosphate group	Membrane structure
Steroid	Four fused carbon rings	Signaling (hormones), membrane fluidity

Example: Phospholipids form the bilayer of cell membranes, providing a barrier and functional interface for cells.

Additional info:

Some content was inferred and expanded for clarity and completeness, based on standard General Biology curriculum topics.