General Biology Study Guide: Chapters 1-3

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Chapter 1: Biological Organization and Scientific Inquiry

Biological Organization

The study of biology involves understanding the hierarchical organization of life, from the biosphere down to molecules. The cell is the fundamental unit of life, and all living things are composed of cells.

Cell: The basic unit of structure and function in living organisms.
Biosphere: The global sum of all ecosystems; the broadest level of biological organization.
Hierarchy: Levels include biosphere, ecosystem, community, population, organism, organ system, organ, tissue, cell, organelle, molecule.
Example: Humans are multicellular organisms composed of trillions of cells organized into tissues and organs.

Emergent Properties

Emergent properties arise when the arrangement and interaction of parts within a system result in new characteristics not present in the individual components.

Definition: Properties that emerge at each level of organization that are not present at the preceding level.
Example: A functioning heart can pump blood, but individual heart cells cannot.

Structure and Function

Biological structures are closely related to their functions. Understanding this relationship helps explain how organisms survive and adapt.

Example: The shape of red blood cells allows them to efficiently transport oxygen.

Unifying Themes of Life

Biology is unified by several key themes, including organization, information flow, energy and matter, interactions, and evolution.

Organization: Living things are highly organized and structured.
Information: Genetic information is stored in DNA and governs cellular activities.
Evolution: Populations change over time through natural selection.

Unity and Diversity of Life

All living organisms share certain characteristics, yet there is immense diversity among species. Natural selection explains how populations adapt and evolve.

Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.
Population: A group of individuals of the same species living in a specific area.

Scientific Process

Science relies on observation, hypothesis formation, experimentation, and analysis. Inductive and deductive reasoning are used to draw conclusions.

Inductive Reasoning: Making generalizations based on specific observations.
Deductive Reasoning: Making predictions based on general principles.
Example: Observing that all organisms are made of cells leads to the cell theory.

Chapter 2: Chemical Foundations of Life

Atoms, Elements, and Isotopes

All matter is composed of atoms, which combine to form elements. Isotopes are variants of elements with different numbers of neutrons.

Atomic Number: Number of protons in an atom.
Mass Number: Sum of protons and neutrons.
Isotopes: Atoms of the same element with different numbers of neutrons. Example: Carbon-12 and Carbon-14.

Chemical Bonds

Atoms interact to form molecules through chemical bonds. The main types are covalent, ionic, and hydrogen bonds.

Covalent Bond: Atoms share electrons. Example: (water)
Ionic Bond: Atoms transfer electrons. Example: (table salt)
Hydrogen Bond: Weak attraction between a hydrogen atom and another electronegative atom.

Electronegativity

Electronegativity is the tendency of an atom to attract electrons in a bond. It determines bond polarity and molecular interactions.

Polar Covalent Bond: Electrons are shared unequally due to differences in electronegativity.
Nonpolar Covalent Bond: Electrons are shared equally.

Reactivity and Electron Configuration

The reactivity of an atom depends on its electron configuration, especially the valence electrons. Atoms seek stability by filling their outermost shell.

Valence Electrons: Electrons in the outermost shell.
Octet Rule: Atoms tend to have eight electrons in their valence shell.
Energy Levels: Electrons occupy discrete energy levels around the nucleus.

Water and Its Importance

Water is essential for life due to its unique properties, such as cohesion, adhesion, high specific heat, and solvent abilities.

Cohesion: Water molecules stick to each other.
Adhesion: Water molecules stick to other substances.
High Specific Heat: Water resists temperature changes.
Solvent: Water dissolves many substances, facilitating chemical reactions.

Chapter 3: Carbon and Biological Molecules

Carbon Skeletons and Organic Molecules

Carbon atoms can form diverse organic molecules due to their ability to make four covalent bonds. This versatility leads to a variety of molecular shapes and functions.

Organic Molecule: Molecule containing carbon and usually hydrogen.
Isomers: Molecules with the same chemical formula but different structures.
Example: Glucose and fructose are isomers.

Major Biological Molecules

Cells contain four major classes of biological molecules: carbohydrates, proteins, lipids, and nucleic acids. Each plays a unique role in cellular structure and function.

Carbohydrates: Provide energy and structural support. Types: Monosaccharides, disaccharides, polysaccharides.
Proteins: Perform a wide range of functions, including catalysis, transport, and structure. Structure: Four levels—primary, secondary, tertiary, quaternary.
Lipids: Include triglycerides, phospholipids, and steroids. Function: Energy storage, membrane structure, signaling.
Nucleic Acids: Store and transmit genetic information. Types: DNA and RNA.

Dehydration Synthesis and Hydrolysis

Biological macromolecules are assembled and broken down by specific chemical reactions.

Dehydration Synthesis: Monomers are joined by removing water to form polymers.
Hydrolysis: Polymers are broken down into monomers by adding water.
Equation:

Comparison of Biological Molecules

The following table summarizes the main biological molecules, their monomers, and functions:

Molecule	Monomer	Function	Example
Carbohydrate	Monosaccharide	Energy, structure	Glucose, cellulose
Protein	Amino acid	Catalysis, structure, transport	Enzymes, hemoglobin
Lipid	Fatty acid, glycerol	Energy storage, membranes	Triglyceride, phospholipid
Nucleic Acid	Nucleotide	Genetic information	DNA, RNA

Saturated vs. Unsaturated Fats

Fats can be classified based on the presence of double bonds in their fatty acid chains.

Saturated Fats: No double bonds; solid at room temperature.
Unsaturated Fats: One or more double bonds; liquid at room temperature.

DNA vs. RNA

DNA and RNA are nucleic acids with distinct structures and functions.

DNA: Double-stranded, stores genetic information.
RNA: Single-stranded, involved in protein synthesis.