Studying the Chemistry of Biology

Key Concepts and Definitions

This section introduces foundational concepts in biology, focusing on the properties of living things, hierarchical organization, and the chemical basis of life. Understanding these principles is essential for further study in biology.

• Order: The highly organized structure of living things.

• Self-regulation: The ability of organisms to maintain internal stability (homeostasis).

• Evolve: The process by which populations of organisms change over generations.

• Homeostasis: Maintenance of a stable internal environment.

• Hierarchical organization: Biological systems are structured in a series of levels, from molecules to the biosphere.

• Emergent properties: New properties that arise at each level of organization.

• Genetic information: Information encoded in DNA that guides the development and functioning of organisms.

• Enzyme: Biological catalysts that speed up chemical reactions.

• Positive and negative feedback loops: Mechanisms that regulate biological processes.

• Divergence: The accumulation of differences between groups, leading to the formation of new species.

Basic Content

Properties and Organization of Living Things

• Properties of Living Things: Living things exhibit order, regulation, growth and development, energy processing, response to the environment, reproduction, and evolutionary adaptation.

• Main Themes of Biology:

  1. Hierarchical organization

  2. Structure-function relationships

  3. Cells as the basic units of life

  4. Genetic information and heredity

  5. Energy and matter transformation

  6. Interactions within and between levels of organization

  7. Evolution and unity/diversity of life

• Levels of Organization: From smallest to largest—molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere.

Conceptual Understanding

• Illustrate properties of living things with examples (e.g., homeostasis in humans, photosynthesis in plants).

• Outline characteristics of scientific hypotheses and theories.

• Differentiate between scientific hypotheses (testable statements) and scientific theories (well-substantiated explanations).

• Explain how biologists use phylogenies to study relatedness and biological diversity.

Critical Thinking

• Distinguish between scientific facts, hypotheses, and theories.

• Rank materials according to their degree of biological organization.

Biological Molecules

Key Terms and Definitions

• Ion: An atom or molecule with a net electric charge.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Molecule: Two or more atoms held together by covalent bonds.

• Chemical bond: The force holding atoms together (e.g., covalent, ionic, hydrogen bonds).

• Covalent bond: A bond formed by sharing electrons between atoms.

• Non-covalent interactions: Weaker interactions such as hydrogen bonds, van der Waals forces.

• Polar molecule: A molecule with an uneven distribution of charge.

• Hydrophilic: Water-loving; substances that dissolve in water.

• Hydrophobic: Water-fearing; substances that do not dissolve in water.

• Hydronium ion: , a water molecule with an extra proton.

• Hydroxide ion: , a water molecule that has lost a proton.

• pH: A measure of hydrogen ion concentration; .

• Acid rain: Rain with a pH lower than 5.6, caused by atmospheric pollution.

Structure and Function of Biological Molecules

• Atoms: Composed of protons, neutrons, and electrons. Atomic number = number of protons; mass number = protons + neutrons.

• Water Molecule: Polar molecule with hydrogen bonds; essential for life.

• Functional Groups: Specific groups of atoms within molecules that have characteristic properties (e.g., hydroxyl, carboxyl, amino, phosphate).

• Monosaccharides, Disaccharides, Polysaccharides: Types of carbohydrates; monosaccharides are simple sugars, disaccharides are two sugars linked, polysaccharides are long chains (e.g., starch, cellulose, glycogen).

• Lipids: Include fats, oils, phospholipids, and steroids. Fats are composed of glycerol and fatty acids; saturated fats have no double bonds, unsaturated fats have one or more double bonds.

• Proteins: Polymers of amino acids; structure includes primary, secondary, tertiary, and quaternary levels.

• Nucleic Acids: DNA and RNA; composed of nucleotides (sugar, phosphate, nitrogenous base).

Table: Comparison of Major Biological Molecules

Conceptual Understanding

• Outline the importance of ions, isotopes, and isomers in biology.

• Distinguish between double bonds and single bonds, polar and nonpolar molecules, acids and bases, hydrophilic and hydrophobic substances.

Critical Thinking

• Given a molecular formula, predict solubility in water based on polarity.

• Explain why some substances dissolve in water and others do not, based on their chemical properties.

• Predict how amino acid structure affects protein folding and function.

• Explain why there are many possible proteins but fewer types of fats and polysaccharides.

Structure and Function of DNA

DNA Structure

• DNA is a double helix composed of two strands of nucleotides.

• Nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).

• Base pairing: A with T, G with C.

• Hydrogen bonds hold the two strands together.

• RNA contains uracil (U) instead of thymine.

Table: DNA vs. RNA

Conceptual Understanding

• Explain how Chargaff’s data and X-ray diffraction studies supported the double helix model of DNA.

• Describe the significance of experiments by Griffith (transformation), Avery (DNA as genetic material), and Chargaff (base composition).

Laboratory Concepts

Lab Skills and Applications

• Types of samples and examples used in biological experiments.

• Types of molecular interactions, their characteristics, and where they are found.

• Types of tests for biomolecules, including positive and negative results, and their biological significance.

Example: The Benedict’s test is used to detect reducing sugars; a positive result is a color change from blue to orange-red.

Additional info: This study guide is based on a syllabus and outlines the key concepts, definitions, and skills expected in a General Biology course, particularly focusing on the chemistry of life and biological molecules.