Overview
This lecture provides a comprehensive review of key concepts in biology including characteristics of life, the scientific method, evolution, chemistry, water properties, and biomolecules for Exam 1.
Characteristics of Life
- Life is defined by traits: organization, metabolism, homeostasis, growth, reproduction, response, and evolution.
- Biotic factors are living; abiotic factors are non-living.
- Emergent properties arise in complex systems but not in their parts.
- Unicellular organisms have one cell; multicellular have many specialized cells.
- Viruses are not considered alive as they lack cells and independent metabolism.
The Scientific Method
- Steps: observation, question, hypothesis, experiment, data/results, conclusion.
- Independent variable is changed; dependent variable is measured.
- Control group is baseline; experimental group receives treatment.
- Hypothesis is a testable prediction; theory is a broad, evidence-backed explanation.
Evolution
- Evolution is change in population genetics over time.
- Natural selection favors traits that improve survival and reproduction.
- All life shares a common ancestor, explaining shared traits.
- Evidence: DNA similarities, fossil records, structural and embryonic likeness.
- Model organisms are used for biological studies relevant to humans.
Chemistry Basics
- Matter consists of atoms; atoms have protons (+), neutrons (0), and electrons (−).
- Atomic number is the count of protons.
- Molecules are bonded atoms; bonds include covalent (shared electrons), ionic (transferred electrons), and hydrogen (weak, polar interactions).
- Electronegativity is an atom’s pull on electrons; oxygen is highly electronegative.
Water Properties
- Water is polar, leading to hydrogen bonding between molecules.
- Cohesion causes water to stick to itself; adhesion makes it stick to other surfaces.
- Water has high specific heat, stabilizing temperature.
- Ice floats because it is less dense than liquid water.
- Water’s polarity makes it an excellent solvent.
Biomolecules
- Carbohydrates (monosaccharides): provide quick energy.
- Lipids (fatty acids + glycerol): store energy, form membranes.
- Proteins (amino acids): provide structure, act as enzymes.
- Nucleic acids (nucleotides): store genetic information (DNA, RNA, ATP).
- Enzymes are proteins that catalyze reactions and are substrate-specific.
- ATP is the cell's main energy source.
Key Terms & Definitions
- Homeostasis — maintaining stable internal conditions
- Emergent Properties — new traits at higher complexity levels
- Hypothesis — testable, experiment-based statement
- Theory — comprehensive, evidence-supported biological explanation
- Natural Selection — process favoring advantageous traits
- Covalent Bond — electron-sharing atomic bond
- Ionic Bond — electron-transferring atomic bond
- Hydrogen Bond — weak bond between polar molecules
- Polarity — unequal distribution of charge in a molecule
- Enzyme — protein that speeds up chemical reactions
- ATP — adenosine triphosphate, the main cellular energy molecule
Action Items / Next Steps
- Review definitions and examples of biomolecules and chemical bonds.
- Practice applying the scientific method to scenarios.
- Study the unique properties of water and their significance.
- Understand the connection between evolution, genetics, and common ancestry.