General Biology: Core Concepts and Study Guide

Chapter 1: Foundations of Biology

Seven Properties Common to All Life

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

• Order: Living things exhibit complex organization.

• Evolutionary adaptation: Populations evolve over generations.

• Response to environment: Organisms respond to stimuli.

• Regulation: Homeostasis maintains internal balance.

• Energy processing: Organisms acquire and use energy.

• Growth and development: Controlled by genetic information.

• Reproduction: Organisms produce offspring.

Levels of Biological Organization

Biological systems are organized hierarchically, from molecules to the biosphere.

• Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

• Each level exhibits emergent properties not present at lower levels.

• Example: A cell is alive, but its individual molecules are not.

Emergent Properties

Emergent properties arise from the arrangement and interaction of parts within a system.

• Example: Photosynthesis occurs in a chloroplast, but not in the separated molecules.

Prokaryotic vs. Eukaryotic Cells

Cells are the basic unit of life, classified as prokaryotic or eukaryotic.

• Prokaryotic cells: No nucleus, smaller, simpler (e.g., bacteria).

• Eukaryotic cells: Nucleus present, larger, complex organelles (e.g., plants, animals).

Domains of Life

Life is classified into three domains based on cell type and genetic differences.

• Bacteria

• Archaea

• Eukarya

Scientific Method: Hypothesis vs. Theory

The scientific method is a systematic approach to inquiry.

• Hypothesis: Testable explanation for observations.

• Theory: Broad, well-supported explanation.

• Controlled experiment: Only one variable is changed at a time.

Quantitative vs. Qualitative Data

• Quantitative: Numerical measurements (e.g., mass, volume).

• Qualitative: Descriptive observations (e.g., color, texture).

Science and Technology

Science seeks understanding; technology applies scientific knowledge for practical purposes.

• Example: DNA research (science) leads to genetic engineering (technology).

Comparing Cells: Prokaryotes vs. Eukaryotes

• Prokaryotes: No membrane-bound organelles.

• Eukaryotes: Membrane-bound organelles, including nucleus.

Structure of DNA

DNA is the hereditary material, composed of nucleotides.

• Double helix structure

• Base pairing: Adenine-Thymine, Cytosine-Guanine

Taxonomy and Classification

Taxonomy is the science of naming and classifying organisms.

• Hierarchy: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Scientific Method Steps

• Observation

• Hypothesis

• Experiment

• Analysis

• Conclusion

• Communicate results

Chapter 2: Chemical Basis of Life

Importance of Chemical Elements

Chemical elements are essential for life; most living matter is composed of a few key elements.

• Major elements: Carbon, Hydrogen, Oxygen, Nitrogen

• Trace elements: Required in small amounts (e.g., iron, iodine)

Structure of Atoms and Compounds

• Atom: Smallest unit of an element, composed of protons, neutrons, electrons

• Compound: Substance formed by two or more elements in fixed ratio

Chemical Bonds

• Ionic bonds: Transfer of electrons

• Covalent bonds: Sharing of electrons

• Hydrogen bonds: Weak attractions between polar molecules

Water Properties

Water is vital for life due to its unique properties.

• Cohesion: Water molecules stick together

• Adhesion: Water molecules stick to other surfaces

• High specific heat: Moderates temperature

• Solvent properties: Dissolves many substances

Acids and Bases

• Acid: Donates H+ ions

• Base: Accepts H+ ions

• pH scale: Measures acidity ($pH = - ext{log}_{10}[ ext{H}^+]$)

Elements in Living Matter

• 96% of living matter: Carbon, Hydrogen, Oxygen, Nitrogen

• Other essential elements: Phosphorus, Sulfur, Calcium, Potassium

Key Terms

• Compound: Substance formed from two or more elements

• Ion: Atom or molecule with electric charge

• Mass number: Sum of protons and neutrons

• Isotope: Atoms of same element with different neutron numbers

Chapter 3: Carbon and Molecular Diversity

Carbon's Role in Life

Carbon's ability to form four covalent bonds makes it the backbone of biological molecules.

• Molecular diversity: Enables formation of complex molecules

Functional Groups

• Important groups: Hydroxyl, carboxyl, amino, phosphate, methyl

• Function: Affect molecular properties and reactivity

Macromolecules

• Monosaccharides: Simple sugars

• Disaccharides: Two sugars joined

• Polysaccharides: Long chains of sugars

• Proteins: Polymers of amino acids

• Lipids: Fats, phospholipids, steroids

• Nucleic acids: DNA and RNA

Structure and Function of Macromolecules

• Proteins: Structure, enzymes, transport

• Lipids: Energy storage, membranes

• Nucleic acids: Genetic information

Fatty Acids

• Saturated: No double bonds, solid at room temperature

• Unsaturated: One or more double bonds, liquid at room temperature

Nucleic Acids

• DNA: Stores genetic information

• RNA: Involved in protein synthesis

Chapter 4: Cell Structure and Function

Microscopy

Microscopes are essential tools for studying cell structure.

• Light microscope: Uses light to magnify images

• Electron microscope: Uses electrons for higher resolution

• Parts: Ocular lens, objective lens, stage, light source

Cell Types

• Prokaryotic: No nucleus, simple structure

• Eukaryotic: Nucleus, complex organelles

Cell Membranes

• Structure: Phospholipid bilayer with embedded proteins

• Function: Controls movement of substances

Compartmentalization

• Allows specialization of cell functions

• Organelles perform specific roles

Animal and Plant Cells

• Animal cells: No cell wall, have centrioles

• Plant cells: Cell wall, chloroplasts, large vacuole

Mitochondria and Chloroplasts

• Mitochondria: Site of cellular respiration

• Chloroplasts: Site of photosynthesis

• Endosymbiosis theory: Origin of these organelles from ancient symbiotic bacteria

Cytoskeleton

• Microfilaments: Actin, cell shape and movement

• Intermediate filaments: Structural support

• Microtubules: Tubulin, cell division, transport

Cilia and Flagella

• Cilia: Short, numerous, move fluid over cell

• Flagella: Long, few, propel cell

Cell Junctions

• Tight junctions: Prevent leakage

• Anchoring junctions: Attach cells together

• Gap junctions: Allow communication

Plant Cell Walls and Plasmodesmata

• Cell wall: Provides structure and protection

• Plasmodesmata: Channels for transport between cells

Organelles in Eukaryotic Cells

• Nucleus: Contains DNA

• Mitochondria: Energy production

• Endoplasmic reticulum: Protein and lipid synthesis

• Golgi apparatus: Modifies and ships proteins

Cell Type	Nucleus	Organelles	Cell Wall
Prokaryotic	No	Few	Yes
Eukaryotic (Animal)	Yes	Many	No
Eukaryotic (Plant)	Yes	Many	Yes

Additional info: Some explanations and examples have been expanded for clarity and completeness.