Fundamental Concepts in GOB Chemistry: Cells, Molecules, and Biological Processes

Biology and Life Characteristics

Introduction to Biology

Biology is the scientific study of life, encompassing the structure, function, growth, origin, evolution, and distribution of living organisms. Understanding the characteristics of life is foundational for GOB Chemistry, as it connects chemical principles to biological systems.

• Biology: Study of living organisms and their interactions.

• Life characteristics: Growth, reproduction, energy use, order, response to environment, homeostasis, adaptation.

• Example: Homeostasis refers to the maintenance of stable internal conditions, such as body temperature.

Cell Theory

Fundamental Principles of Cells

Cell theory is a cornerstone of biology and chemistry, describing the properties and functions of cells as the basic units of life.

• All living things are composed of cells.

• Cells are the basic unit of life.

• All cells arise from pre-existing cells.

Levels of Life

Hierarchical Organization of Biological Systems

Biological systems are organized in a hierarchy from the largest to the smallest components, each level building upon the previous.

• Largest to smallest: Organism → Organ system → Organ → Tissue → Cell → Organelle → Molecule → Atom

• Example: The human body (organism) contains the circulatory system (organ system), which includes the heart (organ), made of cardiac muscle (tissue), composed of muscle cells (cell), containing mitochondria (organelle), made of proteins (molecule), built from atoms.

Evolution & Natural Selection

Mechanisms of Biological Change

Evolution describes changes in populations over time, while natural selection explains how certain traits become more common due to survival and reproduction advantages.

• Evolution: Change in populations over time.

• Natural selection: Traits that enhance survival/reproduction are passed on.

• Example: Dark-colored moths survive better on dark trees due to camouflage.

Antibiotics

Role and Function of Antibiotics

Antibiotics are chemical agents used to treat bacterial infections by killing or inhibiting bacteria, not viruses.

• Kill bacteria, not viruses.

• Examples: Penicillin, amoxicillin.

Domains of Life

Classification of Living Organisms

All living organisms are classified into three domains based on cellular structure and genetic differences.

• Bacteria: Prokaryotes, live everywhere.

• Archaea: Prokaryotes, live in extreme environments.

• Eukarya: Eukaryotes, include animals, plants, fungi, protists.

Classification

Taxonomic Hierarchy

Organisms are classified using a hierarchical system, with each level representing increasing specificity.

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

• Scientific names: Genus species (Genus capitalized, italicized).

Atoms & Electrons

Structure of Atoms

Atoms are the fundamental units of matter, composed of subatomic particles with distinct properties and roles in chemical bonding.

• Protons (+): Located in the nucleus, determine atomic number.

• Neutrons (0): Located in the nucleus, contribute to atomic mass.

• Electrons (-): Orbit around the nucleus, involved in chemical reactions.

• Valence electrons: Located in the outer shell, participate in bond formation.

Chemical Bonds

Types of Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds, with different types based on electron interactions.

• Ionic bond: Transfer of electrons (e.g., NaCl).

• Polar covalent bond: Unequal sharing of electrons (e.g., H2O).

• Nonpolar covalent bond: Equal sharing of electrons (e.g., CH4).

• Hydrogen bond: Weak attraction between H and O/N atoms.

Water Properties

Unique Characteristics of Water

Water exhibits several unique properties due to its molecular structure and hydrogen bonding, making it essential for life.

• Cohesion: Water molecules stick to each other.

• Adhesion: Water molecules stick to other surfaces.

• High heat capacity, excellent solvent, ice floats due to lower density.

pH

Acidity and Basicity

pH measures the concentration of hydrogen ions in a solution, indicating its acidity or basicity.

• Acid: High H+ concentration, low pH.

• Base: High OH- concentration, high pH.

• Neutral: pH = 7.

• Formula: $\text{pH} = -\log[\text{H}^+]$

Biological Macromolecules

Types, Monomers, Polymers, and Functions

Biological macromolecules are large molecules essential for life, each with specific monomers, polymers, and functions.

Type	Monomer	Polymer	Function	Example
Carbohydrate	Monosaccharide	Polysaccharide	Energy, structure	Starch, Glycogen, Cellulose
Protein	Amino acid	Polypeptide	Enzymes, structure	Hemoglobin, enzymes
Nucleic acid	Nucleotide	DNA/RNA	Store information	DNA, RNA
Lipid	Glycerol + fatty acids	Fats, phospholipids	Energy, membranes	Triglycerides, phospholipids

• Dehydration: Makes polymers by removing water.

• Hydrolysis: Breaks polymers by adding water.

Cell Types

Prokaryotes vs. Eukaryotes

Cells are classified as prokaryotic or eukaryotic based on their structure and complexity.

Feature	Prokaryote	Eukaryote
Nucleus	No	Yes
Organelles	No	Yes
Size	Small	Bigger
Examples	Bacteria, Archaea	Animals, Plants, Fungi, Protists

Organelles

Major Cell Structures and Their Functions

Organelles are specialized structures within cells that perform distinct functions necessary for cellular life.

• Nucleus: Contains genetic material (DNA).

• Ribosomes: Synthesize proteins.

• Endoplasmic Reticulum (ER): Protein and lipid synthesis.

• Golgi apparatus: Packages and distributes proteins.

• Lysosomes: Digest cellular waste.

• Mitochondria: Produce energy (ATP).

• Cytoskeleton: Provides cell structure and movement.

• Plant cells: Also have cell wall, chloroplasts, vacuoles.

Membrane & Transport

Cell Membrane Structure and Transport Mechanisms

The cell membrane regulates the movement of substances into and out of the cell through various transport mechanisms.

• Fluidity: Unstructured fats = fluid; saturated fats = less fluid; cholesterol stabilizes.

• Diffusion: Passive movement down concentration gradient.

• Osmosis: Water moves to high solute (low water).

• Tonicity: Hypertonic = shrink, Hypotonic = swell, Isotonic = no change.

• Active transport: Needs energy, moves against gradient.

• Bulk transport: Endocytosis/exocytosis, moves large amounts.

Membrane Fluidity

Factors Affecting Membrane Fluidity

Membrane fluidity is influenced by temperature, fatty acid composition, and cholesterol content.

• Higher temperature = more fluid; lower temperature = less fluid.

• Saturated fatty acids = less fluid; unsaturated fatty acids = more fluid.

• Cholesterol stabilizes: reduces fluidity at high temp, prevents rigidity at low temp.

Diffusion

Passive Movement of Molecules

Diffusion is the passive movement of molecules from areas of high concentration to low concentration, requiring no energy input.

• Small, nonpolar molecules diffuse most easily.

• Example: Oxygen and carbon dioxide gas exchange in lungs.

Osmosis

Water Movement Across Membranes

Osmosis is the passive movement of water across a semipermeable membrane, driven by differences in solute concentration.

• Water moves from high to low water concentration (low to high solute).

• Aquaporins: Protein channels for water transport.

• Tonicity:

  • Hypertonic: Solution has higher solute → cell shrinks.

  • Isotonic: Solution has equal solute → no change.

  • Hypotonic: Solution has lower solute → cell swells (turgor pressure in plants).

Transport Across Membrane

Types and Mechanisms of Membrane Transport

Cells use different transport mechanisms to move substances across membranes, classified by energy requirement and direction.

Type	Energy Required?	Purpose	Example
Passive	No	Molecules move down concentration gradient	Simple diffusion, facilitated diffusion, osmosis
Active	Yes	Molecules move up concentration gradient	Sodium-potassium pump
Bulk	Yes	Move large quantities or particles	Endocytosis, exocytosis

• Formula for diffusion rate: $\text{Rate} = k \times [\text{Concentration gradient}]$

Additional info: These notes provide foundational concepts in GOB Chemistry, including atomic structure, chemical bonding, macromolecules, cell structure, and membrane transport, all essential for understanding the chemical basis of biological systems.