General Biology: Foundations, Chemistry, and Macromolecules

Unit One: Nature of Science

Why Study Biology?

Biology is the study of living organisms and their interactions with the environment. Understanding biology is essential for advancements in medicine, biotechnology, and understanding the natural world.

• Relevance: Biology impacts areas such as drug development and genetic engineering.

• Creation vs. Natural World: Biology reveals the complexity of life and can inform philosophical or theological perspectives.

Scientific Claim vs. Non-Scientific

Scientific claims are based on evidence, are testable, and falsifiable. Non-scientific claims lack empirical support and cannot be tested through scientific methods.

• Testable and Falsifiable: Scientific claims must be reproducible and open to refutation.

• Non-Scientific: Claims that cannot be tested or observed empirically.

Overview of Science

Science is a systematic process for understanding the natural world through observation, experimentation, and evidence-based reasoning.

• Activity or Process: Science seeks to explain phenomena and make predictions.

• Purpose: To form theory—collected information and observations are used to explain phenomena and make predictions in new situations.

Characteristics of Science

• Scientific theories rest on many hypotheses that have been tested.

• Focuses on the natural world.

• Aims to explain the natural world.

• Uses testable ideas.

• Relies on evidence.

• Involves scientific community.

• Benefits from scientific behavior.

• Helps people.

Terminology

• Hypothesis: A proposed explanation or prediction, generally lacks evidence/support but is testable and potentially falsifiable. Can be tested to form a theory.

• Theory: Explanations of why and how things happen in the natural world. Theories are based on evidence collected by many tested hypotheses. Primary goal of science is to form theories.

• Law: Descriptions of what happens, usually expressed in concise statements or mathematical equations. Laws state what nature does consistently. Example: Law of gravity, law of inheritance.

• Additional info: There is no relationship between theory and law; theories explain, laws describe.

Methods of Science

• Observing: Gathering information about phenomena.

• Experimentation: Testing hypotheses under controlled conditions.

• Variables: Elements that can change in an experiment.

  • Independent variable: The factor that is changed or manipulated.

  • Dependent variable: The factor that is measured.

  • Control variables: Factors kept constant to ensure a fair test.

• Sampling Error: Difference between results of a sample and the whole group. Small sample size increases error; blinded studies reduce bias.

• Probability: The measure, as a %, of the chance that an outcome will occur. Calculated as the likelihood of an expected result.

• Statistical Significance: If p-value < 0.05, the result is statistically significant. $p < 0.05$

• Variability: Variation in a set of data is often shown as error bars on a graph.

Chapter 1: Properties of Life

Organization

Living organisms are organized into hierarchical levels, from molecules to biosphere.

• Biosphere: Whole world.

• Ecosystem: Organisms and non-living stuff in different regions.

• Communities: Multiple species living together.

• Population: One species.

• Organism: Individual living thing.

• Tissues, Organs, Organelles, Molecules: Increasing complexity at cellular and molecular levels.

Emergent Properties

Emergent properties result from the arrangement and interaction of parts as complexity increases.

• Correlation between structure and function at each organizational level.

Cell Theory

• The cell is the smallest unit of organization that performs activities required for life.

• Prokaryotic cells: Simple, no nucleus.

• Eukaryotic cells: Membrane-bound nucleus, more complex.

Information

• Genetic info: Chromosomes made up of DNA.

• Genes are units of inheritance.

• Gene expression: DNA → RNA → PROTEIN

Energy & Matter

• All living things must obtain energy and process it.

• Producers: Photosynthesis & cellular respiration.

• Consumers: Feed on other organisms.

Interactions

• Living things interact with each other and the environment.

Evolution

Evolution explains both the unity and diversity of life.

• Microevolution: Small scale genetic changes over time (e.g., antibiotic resistance in bacteria).

• Macroevolution: Large scale changes, all living things descended from a common ancestor.

• Additional info: Some perspectives may not accept macroevolution over billions of years.

Chapter 2: Chemistry for Biology

Structure Determines Function

Chemical structure underlies biological function. Atoms, molecules, and chemical bonds are foundational to life.

Chemical Bonds

• Covalent bonds: Sharing of a pair of valence electrons by 2 atoms.

• Electronegativity: Atom's attraction for electrons in a covalent bond.

• Polar covalent: Unequal sharing (e.g., water molecules).

• Nonpolar covalent: Equal sharing.

• Ionic bonds: Attraction between oppositely charged ions.

• Hydrogen bonds: Weak interactions between polar molecules.

• Van der Waals interactions: Weak, temporary attractions due to electron movement.

Carbon

• Can form diverse molecules (has 4 electrons it can share).

• Organic compounds contain carbon.

Hydrocarbons

• Consist only of hydrogen and carbon.

• Backbone of all organic molecules.

• Release lots of energy.

Isomers

• Same molecular formula but different structures and properties.

• Structural isomers: Different covalent arrangements.

• Cis-trans isomers: Different spatial arrangements around double bonds.

• Enantiomers: Mirror images (e.g., amino acids, drugs).

Functional Groups

• Distinctive properties of organic molecules depend on the carbon skeleton and the chemical groups attached to it.

Chapter 5: Macromolecules

Introduction

Macromolecules are large molecules composed of smaller subunits called monomers. They are essential for life and include carbohydrates, proteins, lipids, and nucleic acids.

Lipids

• Not true macromolecules; not big enough.

Enzymes

• Enzymes are macromolecules that speed up reactions or break down polymers.

• Dehydration synthesis builds polymers; hydrolysis breaks them down.

• Enzymes and water: Hydrolysis requires water.

• Enzymes are always involved!

Carbohydrates

• Include sugars and polymers of sugars.

• Monosaccharides: Simple sugars (e.g., glucose).

• Polysaccharides: Polymers composed of many sugar building blocks.

• GLUCOSE IS THE MOST ABUNDANT

Table: Types of Chemical Bonds

Bond Type	Description	Example
Covalent	Sharing of electron pairs between atoms	H2O, O2
Ionic	Transfer of electrons, attraction between ions	NaCl
Hydrogen	Weak attraction between polar molecules	Between water molecules
Van der Waals	Temporary, weak attractions due to electron movement	Between nonpolar molecules

Table: Levels of Biological Organization

Level	Description
Biosphere	All environments on Earth
Ecosystem	Living and nonliving things in a region
Community	All organisms in an ecosystem
Population	Individuals of one species
Organism	Individual living thing
Organ System	Group of organs working together
Organ	Structure composed of tissues
Tissue	Group of similar cells
Cell	Basic unit of life
Organelle	Functional components in cells
Molecule	Chemical structure of two or more atoms

Example: Application of Scientific Method

• Observation: Smoking babies (looking at something that already happened).

• Experiment: Controlled experiment design to test cause/effect.

Additional info: These notes cover foundational topics in general biology, including the nature of science, properties of life, basic chemistry, and macromolecules. They are suitable for exam preparation and provide a structured overview of key concepts.