BackGeneral Biology: Foundations, Chemical Context, Water, and Carbon
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Ch. 1: Evolution, the Themes of Biology, and Scientific Inquiry
Unifying Themes in Biology
Biology is organized around several unifying themes that help explain the diversity and complexity of life.
Organization: Life is structured at different levels, from molecules to the biosphere.
Information: Genetic information is stored and transmitted via DNA.
Energy and Matter: Life requires energy transfer and transformation.
Interactions: Organisms interact with each other and their environment.
Evolution: Populations of organisms change over time through natural selection.
Levels of Biological Organization
Life can be studied at various levels, from the smallest to the largest:
Biosphere: All life on Earth.
Ecosystem: All living and nonliving things in a particular area.
Community: All organisms in an ecosystem.
Population: Individuals of a species living in an area.
Organism: An individual living thing.
Organ System: Group of organs with a specific function.
Tissue: Group of similar cells.
Cell: Basic unit of life.
Organelle: Functional components within cells.
Molecule: Chemical structure of two or more atoms.
Emergent Properties
Emergent properties arise from the arrangement and interaction of parts as complexity increases.
Reductionism: Studies complex systems by breaking them into simpler components.
Systems Biology: Examines interactions within biological systems.
Structure and Function
Biological structures are closely related to their functions. For example, the shape of a cell enables its specific activity.
Cells: The Basic Unit of Life
All organisms are made of cells.
Cells can be prokaryotic (no nucleus) or eukaryotic (nucleus present).
Genetic Information and DNA
DNA is the molecule that stores genetic information. Genes are units of inheritance, and gene expression is the process of converting genetic information into cellular products (proteins).
DNA is composed of nucleotides: A, T, C, G.
Gene expression leads to protein synthesis.
Energy and Matter
Organisms use energy to carry out life processes. Energy flows through ecosystems, while matter cycles within them.
Energy enters as sunlight and exits as heat.
Chemical nutrients are recycled.
Interactions
Organisms interact with each other and their environment, affecting survival and reproduction.
Interactions can be beneficial or harmful.
Feedback mechanisms regulate biological processes.
Evolution
Evolution explains the unity and diversity of life. Natural selection is the mechanism by which populations adapt over time.
Three domains of life: Bacteria, Archaea, Eukarya.
Bacteria and Archaea are prokaryotic; Eukarya includes all eukaryotes.
Scientific Inquiry
Science uses observation and experimentation to understand natural phenomena.
Discovery Science: Describes nature.
Hypothesis-Driven Science: Explains nature through testing hypotheses.
Inductive Reasoning: Generalizes from observations.
Deductive Reasoning: Uses general premises to make predictions.
Experimental Design
Controlled Experiment: Compares experimental and control groups.
Variables: Independent (manipulated) and dependent (measured).
Ch. 2: The Chemical Context of Life
Atoms and Elements
All matter is composed of atoms, which combine to form elements and compounds.
Atoms: Smallest unit of matter retaining properties of an element.
Elements: Substances that cannot be broken down chemically.
Major elements in life: C, H, O, N, S, P.
Atomic Structure
Protons: Positive charge.
Neutrons: No charge.
Electrons: Negative charge; determine chemical behavior.
Atomic number = number of protons.
Mass number = protons + neutrons.
Isotopes
Isotopes are atoms of the same element with different numbers of neutrons. Some are radioactive and decay over time.
Chemical Bonds
Ionic Bonds: Transfer of electrons between atoms.
Covalent Bonds: Sharing of electron pairs between atoms.
Hydrogen Bonds: Weak bonds between hydrogen and electronegative atoms.
Van der Waals Interactions: Weak attractions between molecules.
Electronegativity
Electronegativity is an atom's ability to attract electrons in a covalent bond.
Chemical Reactions
Chemical reactions make and break chemical bonds.
Reactants are transformed into products.
Reactions can be reversible and reach equilibrium.
Example equation:
Ch. 3: Water and Life
Emergent Properties of Water
Water's unique properties make it essential for life.
Cohesion: Water molecules stick together via hydrogen bonds.
Moderation of Temperature: Water resists temperature changes due to high specific heat.
Expansion upon Freezing: Ice is less dense than liquid water.
Versatility as a Solvent: Water dissolves many substances.
Hydrophilic and Hydrophobic Substances
Hydrophilic: Substances that interact with water.
Hydrophobic: Substances that do not interact with water.
Acids, Bases, and pH
Acid: Increases H+ concentration; pH < 7.
Base: Reduces H+ concentration; pH > 7.
Most biological fluids have pH between 6 and 8.
Buffers
Buffers help maintain stable pH in biological systems by minimizing changes in H+ and OH- concentrations.
Ocean Acidification
Increased CO2 absorption by oceans forms carbonic acid, affecting marine life.
Ch. 4: Carbon and the Molecular Diversity of Life
Organic Molecules and the Origin of Life
Organic molecules are carbon-based and form the foundation of life. Experiments suggest that organic compounds could have formed on early Earth.
Carbon Bonding
Carbon forms four covalent bonds, allowing for diverse molecular structures.
Hydrocarbons are organic molecules consisting of only carbon and hydrogen.
Functional Groups
Functional groups are specific groups of atoms within molecules that confer particular chemical properties.
Additional info: Some explanations and examples have been expanded for clarity and completeness, including definitions, equations, and context for emergent properties and chemical interactions.
