Comprehensive Study Guide for Introductory Biology (BIOL 110)

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Chemistry of Life

Structure of the Atom

Atoms are the fundamental units of matter, composed of subatomic particles that determine their properties and behavior in chemical reactions.

Subatomic Particles: Protons (positive charge, mass ≈ 1 amu), Neutrons (no charge, mass ≈ 1 amu), Electrons (negative charge, negligible mass).
Atomic Number: Number of protons in the nucleus; defines the element.
Atomic Mass: Sum of protons and neutrons.
Isotopes: Atoms of the same element with different numbers of neutrons.
Electron Energy Levels: Electrons occupy shells; energy increases with distance from the nucleus.

Example: Carbon-12 and Carbon-14 are isotopes of carbon.

Acids, Bases, and Salts

Acids, bases, and salts are classes of compounds with distinct properties in aqueous solutions.

Acids: Donate H+ ions (e.g., HCl).
Bases: Accept H+ ions or donate OH- (e.g., NaOH).
Salts: Formed from acid-base reactions (e.g., NaCl).
pH Scale: Measures H+ concentration; ranges from 0 (acidic) to 14 (basic), 7 is neutral.
Buffers: Substances that minimize pH changes.

Example: Blood contains buffers to maintain pH near 7.4.

Chemical Equations and Redox Reactions

Chemical equations represent the transformation of reactants into products. Redox reactions involve electron transfer.

Reactants and Products: Reactants are starting materials; products are formed substances.
Oxidation: Loss of electrons.
Reduction: Gain of electrons.

Equation Example: (cellular respiration)

Chemical Bonds

Bonds hold atoms together in molecules and determine molecular properties.

Ionic Bonds: Transfer of electrons between atoms (e.g., NaCl).
Covalent Bonds: Sharing of electrons; can be single, double, or triple.
Polar Covalent: Unequal sharing (e.g., H2O); Non-polar: Equal sharing (e.g., O2).
Hydrogen Bonds: Weak attractions between polar molecules (e.g., between water molecules).

Comparison Table:

Bond Type	Strength	Example
Covalent	Strongest	H2O
Ionic	Intermediate	NaCl
Hydrogen	Weakest	Between H2O molecules

Properties of Water

Water's unique properties are essential for life.

Cohesion and Adhesion: Water molecules stick to each other and to other surfaces.
High Specific Heat: Resists temperature change.
Solvent Abilities: Dissolves many substances.
Density: Ice is less dense than liquid water.

Properties of Carbon and Functional Groups

Carbon forms the backbone of organic molecules due to its tetravalency.

Macromolecule Formation: Carbon can form long chains and rings.
Functional Groups: Phosphate, methyl, hydroxyl, amine, carboxyl groups confer specific properties.

Example: Amino acids contain amine and carboxyl groups.

Biochemistry of Macromolecules

Macromolecules are large biological molecules essential for life.

Dehydration Synthesis: Joins monomers by removing water.
Hydrolysis: Breaks polymers by adding water.
Carbohydrates: Monosaccharides (e.g., glucose, ), disaccharides (e.g., sucrose), polysaccharides (e.g., starch, cellulose).
Lipids: Triglycerides (glycerol + 3 fatty acids), phospholipids (form bilayers), steroids (e.g., cholesterol).
Proteins: Composed of 20 amino acids; structure levels: primary, secondary, tertiary, quaternary; function depends on 3D shape; denaturation disrupts function.
Nucleic Acids: DNA, RNA, ATP; store and transfer genetic information.

Cells

Characteristics of Life and Cell Theory

All living things share common characteristics and are composed of cells.

Characteristics: Organization, metabolism, homeostasis, growth, reproduction, response to stimuli, evolution.
Levels of Organization: Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism.
Taxonomy: Domains (Bacteria, Archaea, Eukarya); Kingdoms (e.g., Animalia, Plantae).
Cell Theory: All living things are made of cells; cells are the basic unit of life; all cells come from pre-existing cells.

Prokaryotic vs. Eukaryotic Cells

Cells are classified based on internal structure.

Prokaryotic: No membrane-bound organelles; nucleoid region; cell wall; ribosomes.
Eukaryotic: Membrane-bound organelles; nucleus; cytoplasm; endoplasmic reticulum (rough and smooth); Golgi apparatus; mitochondria; chloroplasts (plants); cytoskeleton; vacuoles; lysosomes; peroxisomes; centrioles (animals); cell wall (plants, fungi).
Plant vs. Animal Cells: Plant cells have cell walls, chloroplasts, central vacuole; animal cells have centrioles, lysosomes.

Endosymbiotic Theory

Mitochondria and chloroplasts originated from free-living prokaryotes engulfed by ancestral eukaryotic cells.

Evidence: Double membranes, own DNA, ribosomes similar to bacteria.

Membranes

Fluid Mosaic Model

The plasma membrane is a dynamic structure composed of lipids, proteins, and carbohydrates.

Phospholipids: Form bilayer; hydrophilic heads, hydrophobic tails.
Proteins: Channels, receptors, transporters.
Cholesterol: Modulates fluidity.
Glycoproteins/Glycolipids: Cell recognition.

Transport Across Membranes

Passive Transport: No energy required; includes diffusion, osmosis, facilitated diffusion.
Active Transport: Requires ATP; moves substances against gradient (e.g., Na+/K+ pump).
Endocytosis/Exocytosis: Bulk transport into/out of cell.

Comparison Table:

Transport Type	Energy Required?	Direction	Example
Passive	No	High → Low	O2 diffusion
Active	Yes (ATP)	Low → High	Na+/K+ pump

Enzymes

Structure and Function

Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy.

Active Site: Region where substrate binds.
Allosteric Site: Regulatory site for enzyme activity.
Coenzymes: Non-protein helpers (e.g., NAD, FAD).
Factors Affecting Activity: Temperature, pH, substrate concentration, inhibitors (competitive, non-competitive).

Metabolism and ATP

Metabolic Pathways

Metabolism includes all chemical reactions in a cell, divided into anabolism (building up) and catabolism (breaking down).

Energy: Capacity to do work; exists as potential (stored) or kinetic (motion).
First Law of Thermodynamics: Energy cannot be created or destroyed.
Second Law: Entropy (disorder) increases.
Exergonic: Releases energy; Endergonic: Requires energy.

ATP: The Energy Currency

Structure: Adenosine triphosphate (adenine + ribose + 3 phosphates).
Function: Transfers energy via phosphorylation.
Phosphorylation: Substrate-level and chemiosmotic (oxidative phosphorylation).

Equation:

Photosynthesis

Overview and Reactions

Photosynthesis converts light energy into chemical energy in plants, algae, and some bacteria.

General Equation:
Light-Dependent Reactions: Occur in thylakoid membranes; produce ATP, NADPH, O2.
Calvin Cycle (Light-Independent): Occurs in stroma; uses ATP, NADPH, CO2 to make glucose.
Pigments: Chlorophyll a, b, carotenoids; absorb light energy.

Cellular Respiration and Fermentation

Energy-Releasing Pathways

Cells extract energy from glucose via aerobic or anaerobic pathways.

Glycolysis: Cytoplasm; glucose → 2 pyruvate, 2 ATP, 2 NADH.
Aerobic Respiration: Includes Krebs cycle (mitochondrial matrix) and electron transport chain (inner mitochondrial membrane); produces up to 36-38 ATP per glucose.
Fermentation: Anaerobic; produces lactic acid or ethanol; yields 2 ATP per glucose.

Genetics: DNA, RNA, and Protein Synthesis

DNA Structure and Replication

DNA stores genetic information; replication ensures faithful transmission.

Structure: Double helix; sugar-phosphate backbone; complementary base pairing (A-T, G-C); antiparallel strands (3' and 5' ends).
Replication: Semi-conservative; enzymes include helicase, primase, DNA polymerase, ligase.

RNA and Protein Synthesis

RNA Types: mRNA (messenger), tRNA (transfer), rRNA (ribosomal).
Transcription: DNA → mRNA; occurs in nucleus.
Translation: mRNA → protein; occurs in ribosome; uses codons and anticodons.
Mutations: Changes in DNA sequence; can be silent, missense, nonsense, or frameshift; source of genetic variation.

Cell Division

Mitosis and Meiosis

Mitosis: Produces two identical diploid cells; stages: prophase, metaphase, anaphase, telophase.
Meiosis: Produces four non-identical haploid gametes; includes crossing over and independent assortment for genetic diversity.
Binary Fission: Prokaryotic cell division.

Classical Genetics

Mendelian Inheritance

Key Terms: Allele, locus, dominant, recessive, homozygous, heterozygous, genotype, phenotype.
Mendel's Laws: Segregation, independent assortment.
Non-Mendelian: Incomplete dominance, codominance (e.g., ABO blood types), sex-linked traits.

Biotechnology

Techniques and Applications

Restriction Enzymes: Cut DNA at specific sequences.
Gel Electrophoresis: Separates DNA fragments by size.
Recombinant DNA: Combining DNA from different sources.
Stem Cells: Undifferentiated cells with potential for therapy.
Genomics: Study of genomes; applications in medicine, agriculture.

Evolution

Principles and Evidence

Definition: Change in genetic composition of populations over time.
Natural Selection: Mechanism proposed by Darwin; differential survival and reproduction.
Evidence: Fossils, comparative anatomy, molecular biology, observed microevolution (e.g., antibiotic resistance).

Scientific Inquiry and Laboratory Skills

Scientific Method

Steps: Observation, hypothesis, experiment, data analysis, conclusion.
Hypothesis vs. Theory: Hypothesis is a testable statement; theory is a well-supported explanation.
Controls: Positive and negative controls in experiments.

Measurement and Microscopy

Metric System: Standard units (kilo-, centi-, milli-, micro-).
Microscope Use: Parts, magnification, resolution, contrast.

Additional info: This guide covers foundational topics in introductory biology, including biochemistry, cell structure, genetics, metabolism, evolution, and scientific methods, as outlined in a typical college-level biology course.