Chapter 1: 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.

• Definition: Biology investigates the processes and principles underlying life.

Scope: Includes molecular biology, ecology, genetics, physiology, and more.

Characteristics of Living Things

All living things share certain characteristics that distinguish them from non-living matter.

Order: Organized structure, often in cells.

Reproduction: Ability to produce offspring.

Growth and Development: Increase in size and change over time.

Energy Processing: Use of energy for metabolic processes.

Response to Environment: Reacting to stimuli.

Regulation: Maintaining internal balance (homeostasis).

Evolutionary Adaptation: Populations change over generations.

Evolution and Natural Selection

Evolution explains the diversity of life through changes in populations over time, primarily driven by natural selection.

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

Adaptation: Traits that improve survival and reproduction.

Mutation: Source of genetic variation.

Levels of Biological Organization

Biological systems are organized in a hierarchy from smallest to largest.

1. Atom

2. Molecule

3. Organelle

4. Cell

5. Tissue

6. Organ

7. Organ System

8. Organism

9. Population

10. Community

11. Ecosystem

12. Biosphere

Domains of Life

All living organisms are classified into three domains:

Bacteria: Prokaryotic, unicellular organisms.

Archaea: Prokaryotic, often extremophiles.

Eukarya: Eukaryotic organisms, including plants, animals, fungi, and protists.

Binomial System of Naming Organisms

The binomial nomenclature system gives each species a two-part scientific name (Genus species), e.g., Homo sapiens.

Genus: First part, capitalized.

Species: Second part, lowercase.

Scientific Method

The scientific method is a systematic approach to inquiry.

1. Observation

2. Question

3. Hypothesis

4. Experiment

5. Data Collection

6. Analysis

7. Conclusion

Hypothesis vs. Scientific Theory

Hypothesis: A testable, tentative explanation for an observation.

Scientific Theory: A well-substantiated explanation based on a body of evidence.

Chapter 2: Chemistry of Life

Key Terms and Definitions

Element: A substance that cannot be broken down into simpler substances by chemical means.

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

Atomic Number: Number of protons in an atom's nucleus.

Mass Number: Total number of protons and neutrons.

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

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

Cohesion: Attraction between molecules of the same substance.

Adhesion: Attraction between molecules of different substances.

Hydrophobic: Repelled by water.

Hydrophilic: Attracted to water.

Atomic Structure

Atoms consist of a nucleus (protons and neutrons) and electrons in orbitals.

Electrons determine chemical behavior.

Chemical Bonds

Ionic Bonds: Transfer of electrons between atoms.

Covalent Bonds: Sharing of electrons between atoms.

Hydrogen Bonds: Weak attraction between a hydrogen atom and an electronegative atom.

Water and Its Properties

Polarity: Water is a polar molecule, leading to hydrogen bonding.

Solvent: Water dissolves many substances (universal solvent).

Hydrophilic vs. Hydrophobic: Hydrophilic substances dissolve in water; hydrophobic do not.

Solution: A homogeneous mixture of solute dissolved in solvent.

Chapter 3: Biological Molecules

Properties of Carbon

Carbon is the central element in biological molecules due to its ability to form four covalent bonds.

Versatility: Forms chains, rings, and complex structures.

Organic Molecules: Contain carbon and hydrogen.

Organic and Inorganic Molecules

Organic: Molecules with carbon-hydrogen bonds (e.g., glucose).

Inorganic: Molecules without carbon-hydrogen bonds (e.g., water, salts).

Functional Groups

Groups of atoms that confer specific chemical properties to molecules (e.g., hydroxyl, carboxyl, amino).

Hydrolysis and Dehydration Synthesis

Dehydration Synthesis: Joins monomers by removing water.

Hydrolysis: Breaks polymers into monomers by adding water.

Chapter 4: The Cell

Cell Theory

All living things are composed of cells.

Cells are the basic unit of structure and function.

All cells arise from pre-existing cells.

Prokaryotic vs. Eukaryotic Cells

Prokaryotic: No nucleus, simple structure (e.g., bacteria).

Eukaryotic: Nucleus, membrane-bound organelles (e.g., plants, animals).

Cell Structures and Functions

Cell Wall: Provides structure (plants, fungi, bacteria).

Chloroplast: Site of photosynthesis (plants, algae).

Cytoskeleton: Maintains cell shape, aids movement.

Endoplasmic Reticulum: Protein and lipid synthesis.

Golgi Apparatus: Modifies, sorts, and packages proteins.

Lysosomes: Digestion and waste removal.

Mitochondria: ATP production (cellular respiration).

Nucleus: Contains genetic material (DNA).

Nucleolus: Ribosome synthesis.

Ribosomes: Protein synthesis.

Types of Cells

Plant cells have cell walls and chloroplasts; animal cells do not.

Bacterial cells lack a nucleus and membrane-bound organelles.

Chapter 5: Cell Membranes and Transport

Fluid Mosaic Model and Selective Permeability

Fluid Mosaic Model: Describes the cell membrane as a flexible layer with proteins embedded in or attached to a phospholipid bilayer.

Selectively Permeable: Allows some substances to pass while blocking others.

Cell Membrane Structure and Function

Composed of phospholipids, proteins, cholesterol, and carbohydrates.

Proteins serve as channels, receptors, and enzymes.

Carbohydrates are involved in cell recognition.

Membrane Proteins

Integral proteins span the membrane; peripheral proteins are on the surface.

Functions include transport, signaling, and structural support.

Transport Across Membranes

Diffusion: Movement of molecules from high to low concentration.

Osmosis: Diffusion of water across a selectively permeable membrane.

Active Transport: Movement against concentration gradient, requires energy.

Endocytosis: Uptake of materials by engulfing them in the membrane.

Exocytosis: Release of materials from the cell.

Osmotic Solutions

Isotonic: Equal solute concentration inside and outside the cell.

Hypotonic: Lower solute concentration outside; cell may swell.

Hypertonic: Higher solute concentration outside; cell may shrink.

Table: Types of Membrane Transport