FUNDAMENTALS OF BIOLOGY - CLASS NOTES
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TABLE OF CONTENTS
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1. Introduction to Biology and Scientific Method
2. Cell Biology and Cellular Structures
3. Molecular Biology and Biochemistry
4. Genetics and Heredity
5. Evolution and Natural Selection
6. Ecology and Ecosystems
7. Plant and Animal Biology
8. Biological Processes and Systems
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1. INTRODUCTION TO BIOLOGY AND SCIENTIFIC METHOD
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What is Biology?
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* Biology is the scientific study of life and living organisms
* Encompasses the study of structure, function, growth, origin, evolution, and
distribution of living things
* Integrates theoretical and experimental approaches to understand life processes
The Scientific Method
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* Systematic approach to understanding the natural world
* Steps include:
- Observation
- Hypothesis formation
- Experimentation
- Data analysis
- Conclusion drawing
- Peer review and replication
Organization of Living Things
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* Hierarchical organization from atoms to biosphere:
- Atoms → Molecules → Organelles → Cells → Tissues → Organs → Organ Systems →
Organisms → Populations → Communities → Ecosystems → Biosphere
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2. CELL BIOLOGY AND CELLULAR STRUCTURES
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Fundamental Cell Types
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Prokaryotic Cells:
* Lack a membrane-bound nucleus
* Simpler cellular structure
* No membrane-bound organelles
* Divide by binary fission
* Examples: Bacteria and Archaea
* Genetic material freely floating in cytoplasm
Eukaryotic Cells:
* Contain a membrane-bound nucleus
* Complex cellular structure with specialized organelles
* Have linear DNA contained within nucleus
* Reproduce via mitosis and meiosis
* Examples: Plants, animals, fungi, protists
Key Cellular Organelles and Functions
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Nucleus:
* Control center of the cell
* Contains genetic material (DNA)
* Directs cellular activities
* Surrounded by nuclear envelope with pores
Mitochondria:
* Known as the "powerhouse of the cell"
* Responsible for energy production through cellular respiration
* Generates ATP (adenosine triphosphate)
* Contains its own DNA and ribosomes
Endoplasmic Reticulum (ER):
* Rough ER: Studded with ribosomes, involved in protein synthesis
* Smooth ER: Lacks ribosomes, involved in lipid synthesis and detoxification
Golgi Apparatus:
* Modifies, sorts, and packages proteins from ER
* Crucial for protein processing and secretion
* Consists of flattened membrane sacs called cisternae
Ribosomes:
* Sites of protein synthesis
* Can be free-floating or attached to ER
* Composed of ribosomal RNA and proteins
Lysosomes:
* Contain digestive enzymes
* Break down cellular waste and worn-out organelles
* Important for cellular maintenance and recycling
Cytoskeleton:
* Network of protein filaments providing structural support
* Includes microtubules, microfilaments, and intermediate filaments
* Important for cell shape, organelle movement, and cell division
Cell Membrane Structure and Function
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* Phospholipid bilayer with embedded proteins
* Selectively permeable barrier
* Controls what enters and exits the cell
* Contains cholesterol for membrane fluidity
* Membrane proteins serve various functions: transport, recognition, enzymatic
activity
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3. MOLECULAR BIOLOGY AND BIOCHEMISTRY
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Central Dogma of Molecular Biology
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* DNA → RNA → Protein
* Describes the flow of genetic information in cells
* Two key processes: Transcription and Translation
DNA Structure and Function
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* Double helix structure discovered by Watson and Crick
* Composed of nucleotides: adenine (A), thymine (T), guanine (G), cytosine (C)
* Base pairing rules: A pairs with T, G pairs with C
* Antiparallel strands held together by hydrogen bonds
* Contains genetic instructions for all cellular activities
RNA Types and Functions
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* Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes
* Transfer RNA (tRNA): Brings amino acids to ribosomes during protein synthesis
* Ribosomal RNA (rRNA): Structural component of ribosomes
* Single-stranded molecule with uracil (U) instead of thymine
Transcription Process
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* Converting DNA sequence into RNA molecule
* RNA polymerase enzyme reads DNA template strand
* Creates complementary RNA strand
* Occurs in nucleus (eukaryotes) or cytoplasm (prokaryotes)
* Only coding DNA sequences are transcribed
Translation Process
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* Using mRNA to create proteins
* Takes place at ribosomes in cytoplasm
* tRNA molecules bring specific amino acids
* Genetic code determines amino acid sequence
The Genetic Code
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* Consists of 64 codons (triplets of nucleotides)
* Each codon specifies one amino acid or stop signal
* Start codon (AUG) initiates protein synthesis
* Three stop codons (UAA, UAG, UGA) terminate synthesis
* Code is universal across most living organisms
Protein Structure and Function
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* Primary structure: Amino acid sequence
* Secondary structure: Alpha helices and beta sheets
* Tertiary structure: 3D folding of protein chain
* Quaternary structure: Multiple protein chains together
* 20 different amino acids create protein diversity
* Functions include enzymes, structural proteins, transport proteins, hormones
Cellular Metabolism
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* Catabolism: Breaking down molecules for energy
* Anabolism: Building complex molecules from simpler ones
* ATP serves as cellular energy currency
* Enzymes catalyze biochemical reactions by lowering activation energy
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4. GENETICS AND HEREDITY
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Mendelian Genetics
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* Developed by Gregor Mendel through pea plant experiments
* Foundation of modern genetics
Key Genetic Terminology:
* Gene: Unit of heredity
* Allele: Variant form of a gene
* Genotype: Genetic makeup of an organism
* Phenotype: Observable physical characteristics
* Dominant allele: Masks expression of recessive allele
* Recessive allele: Only expressed when homozygous
* Homozygous: Two identical alleles (AA or aa)
* Heterozygous: Two different alleles (Aa)
Mendel's Laws
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Law of Segregation:
* Each organism has two alleles for each characteristic
* Alleles separate during gamete formation
* Each gamete receives only one allele per gene
Law of Independent Assortment:
* Genes for different traits are inherited independently
* Applies to genes on different chromosomes
Principle of Dominance:
* In heterozygous organisms, dominant allele is expressed
* Recessive allele remains present but not expressed
Inheritance Patterns
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* Complete dominance: Dominant allele completely masks recessive
* Incomplete dominance: Heterozygote shows intermediate phenotype
* Codominance: Both alleles expressed simultaneously
* Multiple alleles: More than two alleles exist for a gene
* Sex-linked inheritance: Genes located on sex chromosomes
Chromosomes and Cell Division
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Mitosis:
* Cell division producing identical diploid cells
* Phases: Prophase, Metaphase, Anaphase, Telophase
* Maintains chromosome number
* Important for growth and repair
Meiosis:
* Cell division producing genetically diverse gametes
* Reduces chromosome number by half (diploid to haploid)
* Two divisions: Meiosis I and Meiosis II
* Creates genetic diversity through crossing over and independent assortment
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5. EVOLUTION AND NATURAL SELECTION
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Charles Darwin and Evolutionary Theory
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* Developed theory of evolution through natural selection
* Published "On the Origin of Species" (1859)
* Proposed that species evolve through gradual changes over time
Mechanisms of Evolution
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Natural Selection:
* Individuals with beneficial traits have higher survival and reproduction rates
* Genetic variations within populations enable adaptive changes
* Traits improving survival are passed to offspring
* Results in evolution of populations over time
Genetic Drift:
* Random changes in gene frequencies
* More significant in small populations
* Can reduce genetic diversity
* Less predictable than natural selection
Gene Flow:
* Movement of alleles between populations
* Increases genetic diversity within populations
* Can introduce new alleles or change allele frequencies
Mutation:
* Changes in DNA sequence
* Source of genetic variation
* Can be beneficial, harmful, or neutral
Evidence for Evolution
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Fossil Record:
* Shows progression of life forms over time
* Demonstrates extinction and appearance of new species
* Provides timeline of evolutionary changes
Comparative Anatomy:
* Homologous structures: Similar structure, different function
* Analogous structures: Similar function, different structure
* Vestigial structures: Remnants of ancestral features
Molecular Evidence:
* DNA and protein similarities indicate evolutionary relationships
* Molecular clocks estimate divergence times
* Phylogenetic trees show evolutionary relationships
Biogeography:
* Distribution of species reflects evolutionary history
* Island biogeography demonstrates adaptive radiation
Speciation
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* Process by which new species form
* Reproductive isolation prevents gene flow
* Geographic isolation often leads to speciation
* Can occur through gradual change or rapid bursts
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6. ECOLOGY AND ECOSYSTEMS
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Levels of Ecological Organization
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* Individual: Single organism
* Population: Group of same species in same area
* Community: All populations in an area
* Ecosystem: Community plus physical environment
* Biome: Large geographic area with similar climate
* Biosphere: All life on Earth
Ecosystem Components
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Biotic Factors:
* Living components of ecosystem
* Producers, consumers, decomposers
* Interactions between organisms
Abiotic Factors:
* Non-living components
* Temperature, water, soil, sunlight, pH
* Influence organism distribution and survival
Energy Flow in Ecosystems
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* Primary producers: Convert solar energy to chemical energy
* Primary consumers: Herbivores that eat producers
* Secondary consumers: Carnivores that eat herbivores
* Tertiary consumers: Top predators
* Decomposers: Break down dead organic matter
* Energy flows in one direction through trophic levels
Nutrient Cycling
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* Carbon cycle: Movement of carbon through ecosystem
* Nitrogen cycle: Conversion of nitrogen between forms
* Phosphorus cycle: Movement of phosphorus through ecosystem
* Water cycle: Continuous movement of water
Population Dynamics
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* Population growth patterns: Exponential and logistic
* Carrying capacity: Maximum population size environment can support
* Limiting factors: Resources that restrict population growth
* Population interactions: Competition, predation, symbiosis
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7. PLANT AND ANIMAL BIOLOGY
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Plant Biology
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Plant Structure:
* Roots: Absorption of water and nutrients, anchorage
* Stems: Support, transport, storage
* Leaves: Photosynthesis, gas exchange
* Flowers: Reproduction
* Seeds: Dispersal and protection of embryos
Photosynthesis:
* Process converting light energy to chemical energy
* Occurs in chloroplasts
* Light reactions: Convert light to ATP and NADPH
* Calvin cycle: Uses ATP and NADPH to fix carbon dioxide
* Overall equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
Plant Reproduction:
* Sexual reproduction through flowers and seeds
* Asexual reproduction through vegetative propagation
* Alternation of generations: Sporophyte and gametophyte phases
Animal Biology
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Animal Body Systems:
* Digestive system: Breaks down food for absorption
* Circulatory system: Transports materials throughout body
* Respiratory system: Gas exchange
* Nervous system: Coordination and control
* Endocrine system: Hormone regulation
* Immune system: Defense against pathogens
* Reproductive system: Production of offspring
Animal Behavior:
* Innate behaviors: Genetically programmed
* Learned behaviors: Modified through experience
* Social behaviors: Interactions between individuals
* Communication: Transfer of information between animals
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8. BIOLOGICAL PROCESSES AND SYSTEMS
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Cellular Respiration
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* Process breaking down glucose to produce ATP
* Three stages: Glycolysis, Krebs cycle, Electron transport chain
* Occurs in mitochondria (eukaryotes) or cytoplasm (prokaryotes)
* Overall equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Homeostasis
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* Maintenance of stable internal conditions
* Negative feedback mechanisms maintain balance
* Examples: Temperature regulation, blood glucose control
* Essential for proper cellular function
Immune System
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* Innate immunity: Non-specific first line of defense
* Adaptive immunity: Specific response to particular pathogens
* Antibodies: Proteins that recognize and neutralize antigens
* Memory cells: Provide long-term immunity
Important Scientists in Biology
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* Charles Darwin: Theory of evolution
* Gregor Mendel: Laws of inheritance
* James Watson and Francis Crick: DNA structure
* Barbara McClintock: Genetic transposition
* Lynn Margulis: Endosymbiotic theory
* Alexander Fleming: Discovery of penicillin
STUDY TIPS
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* Focus on understanding concepts rather than memorization
* Practice drawing and labeling diagrams
* Connect different biological processes and systems
* Use active learning techniques like teaching others
* Review regularly and space out study sessions
* Apply biological concepts to real-world examples
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END OF BIOLOGY NOTES
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