Chapter 1: What is Biology?

Introduction to Biology

Biology is the scientific study of life and living organisms. This chapter introduces the foundational concepts and terminology necessary for understanding biological systems.

• Definition of Biology: Biology is the study of living things and their vital processes.

• Underlying Themes: Major themes include organization, information flow, energy and matter, interactions, and evolution.

Levels of Organization in Life

• Hierarchy: Life is organized into hierarchical levels: atom, molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, and biosphere.

• Order of Levels: Be able to list and arrange these levels from smallest to largest or vice versa.

Genomes and Genetic Information

• Genome: The complete set of genetic material in an organism.

• Inheritance: Genetic information is passed from parent to offspring through the genome.

Consumers and Producers

• Producer: An organism that can make its own food, usually through photosynthesis (e.g., plants).

• Consumer: An organism that obtains energy by feeding on other organisms (e.g., animals).

The Scientific Method

• Steps: Observation, hypothesis, experiment, data collection, analysis, and conclusion.

• Order: Be able to put the steps in the correct order.

Peer-Review Process

• Definition: The evaluation of scientific work by others working in the same field to ensure accuracy and validity.

Chapter 22: Biology of Evolution

Introduction to Evolution

Evolution is the process by which populations of organisms change over generations. This chapter covers the mechanisms and evidence for evolution.

• Survival of the Fittest: The concept that individuals best adapted to their environment are more likely to survive and reproduce.

• Organization of Organisms: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Species and Speciation

• Species: A group of organisms that can interbreed and produce fertile offspring.

• Speciation: The formation of new and distinct species in the course of evolution.

• Example: Darwin’s finches on the Galápagos Islands, which evolved different beak shapes to exploit different food sources.

Fossil Record and Strata

• Fossil: The preserved remains or traces of organisms from the past.

• Strata: Layers of sedimentary rock that contain fossils; used to determine the relative ages of fossils.

• Contribution to Evolution: Fossils provide evidence for the history of life and evolutionary changes.

Natural Selection and Hardy-Weinberg Equilibrium

• Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.

• Genetic Drift: Random changes in allele frequencies in a population.

• Gene Flow: The transfer of genetic material between populations.

• Hardy-Weinberg Principle: Describes a non-evolving population where allele and genotype frequencies remain constant.

Hardy-Weinberg Equation:

Where p and q are the frequencies of two alleles in a population.

• Bottleneck Effect: A sharp reduction in the size of a population due to environmental events.

• Founder Effect: Reduced genetic diversity when a population is descended from a small number of colonizing ancestors.

Chapter 5: Biological Molecules

Introduction to Biological Molecules

Biological molecules are essential for life and include carbohydrates, lipids, proteins, and nucleic acids. These macromolecules have unique structures and functions.

Carbohydrates

• Definition: Organic molecules composed of carbon, hydrogen, and oxygen, typically in a 1:2:1 ratio.

• Monomers and Polymers: Monosaccharides (simple sugars) are the monomers; polysaccharides are the polymers.

• Functions: Provide energy (e.g., glucose), structural support (e.g., cellulose in plants).

• Examples: Starch (plants), glycogen (animals), cellulose (plants).

Lipids

• Definition: Hydrophobic molecules including fats, oils, and steroids.

• Functions: Energy storage, insulation, and making up cell membranes.

• Saturated vs. Unsaturated Fats: Saturated fats have no double bonds between carbon atoms; unsaturated fats have one or more double bonds.

• Effect on Health: Saturated fats are typically solid at room temperature and can contribute to heart disease; unsaturated fats are usually liquid and considered healthier.

Proteins

• Definition: Polymers of amino acids linked by peptide bonds.

• Structure: Proteins have four levels of structure:

  • Primary: Sequence of amino acids.

  • Secondary: Local folding (alpha helices and beta sheets).

  • Tertiary: Overall 3D shape.

  • Quaternary: Association of multiple polypeptide chains.

• Amino Acids: There are 20 different amino acids, each with a unique R group (side chain) that determines its properties (nonpolar, polar, electrically charged).

• Protein Folding: The shape of a protein determines its function; folding is influenced by the chemical properties of amino acids.

• Denaturation: The loss of a protein’s structure (and function) due to external stress (e.g., heat, pH); this process is often irreversible.

Nucleic Acids

• Definition: Polymers made of nucleotide monomers; store and transmit genetic information.

• Types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

• Functions: DNA stores genetic information; RNA is involved in protein synthesis and gene regulation.

• Differences between DNA and RNA:

  • DNA contains deoxyribose; RNA contains ribose.

  • DNA uses the bases A, T, C, G; RNA uses A, U, C, G (U = uracil replaces T = thymine).

  • DNA is double-stranded and forms a double helix; RNA is usually single-stranded.

  • DNA strands are antiparallel (run in opposite directions).

• Nitrogenous Bases: Purines (adenine, guanine) and pyrimidines (cytosine, thymine, uracil).

• Base Pairing: In DNA, A pairs with T, and C pairs with G; in RNA, A pairs with U.

Summary Table: Comparison of Biological Macromolecules