Environmental Bio

ENVIRONMENTAL BIOLOGY - LECTURE NOTES SUMMARY

LEVELS OF BIOLOGICAL ORGANIZATION

- Molecule: The chemical building block of life.

- Organelle: Functional components within a cell.

- Cellular: The cell itself, which is the fundamental unit of life.

- Tissue: A group of similar cells working together.

- Organ: Multiple tissues forming a functional structure.

- System: Organs working together (e.g., digestive system).

- Organism: An individual living thing.

- Population: A group of the same species living together.

- Ecosystem: Biological community interacting with its physical environment.

- Biosphere: The global ecological system integrating all living beings.

THE CELL

- The cell is the smallest unit of life and a component of every living organism.

- Prokaryotic cells: Smaller, single-celled organisms with no nucleus or internal membrane-bound organelles. Examples include Bacteria and Archaea.

- Eukaryotic cells: Cells containing a true nucleus and internal membrane-bound organelles. They can be multicellular or single-celled. Examples include plants, animals, fungi, and single-celled protists.

MACROMOLECULES & ORGANIC COMPOUNDS

- Organic compounds: Complex molecules containing Carbon (C) bonded to Hydrogen (H), Oxygen (O), Nitrogen (N), Sulfur (S), or Phosphorus (P).

- Major groups: Carbohydrates, Lipids, Proteins, and Nucleic Acids.

- Macromolecules: Large biological molecules including carbohydrates, proteins, and nucleic acids.

- Polymers: Long chains of repeating units called monomers, joined by covalent bonds.

- Monomers: The building blocks of polymers that may also have independent functions.

GENETIC MATERIAL

- DNA (Deoxyribonucleic acid): Stores inherited genetic information.

- RNA (Ribonucleic acid): Transfers genetic information from DNA to ribosomes for protein synthesis.

- RNA types: mRNA (messenger), tRNA (transfer), rRNA (ribosomal). Some RNAs regulate gene expression.

CELL CYCLE & MITOSIS

- Interphase: Accounts for 90% of the cell cycle. Consists of G1 (cell growth), S phase (DNA Replication), and G2 (preparation for division).

- Mitosis: The division of the nucleus. It has five stages: Prophase, Prometaphase, Metaphase, Anaphase, and Telophase.

- Cytokinesis: The division of the cytoplasm, occurring right after mitosis.

- Binary Fission: Asexual reproduction used by bacteria, archaea, and unicellular eukaryotes where a single cell grows to twice its size and splits into two identical daughter cells.

MEIOSIS & GENETIC VARIATION

- Meiosis: Cell division that reduces chromosome number from diploid (2n) to haploid (n) to produce 4 unique daughter cells (gametes).

- Asexual vs. Sexual: Asexual reproduction involves only 1 parent and produces genetic clones (variation only occurs via mutation). Sexual reproduction involves 2 parents fusing gametes, resulting in unique genetic combinations.

- Sources of Genetic Variation:

1. Independent assortment: Random alignment and placing of homologous pairs.

2. Crossing over: Homologous chromosomes pair up and non-sister chromatids exchange DNA sections in Prophase I, producing recombinant chromosomes.

3. Random fertilization: Any sperm can fertilize any egg.

4. Mutations: Permanent changes in the DNA sequence.

HISTORY OF EVOLUTIONARY THOUGHT

- Aristotle: Early Greek philosopher who suggested life will change but ultimately believed species were fixed and unchanging. He arranged life on a rigid "scale of nature" that fit a religious worldview.

- Carolus Linnaeus: Developed taxonomy to classify life's diversity. Mnemonic: King Phillip Came Over For Great Spaghetti (Kingdom, Phylum, Class, Order, Family, Genus, Species). Scientific names use Genus (capitalized) and species (lowercase), fully italicized or underlined.

- Georges Cuvier: Paleontologist who believed extinction was real but rejected evolution. He championed Catastrophism, stating sudden catastrophic events (not gradual evolution) caused mass extinctions.

- James Hutton & Charles Lyell: Proposed Uniformitarianism, concluding the Earth changes very slowly over time through gradual geologic features and processes.

- Erasmus Darwin: Suggested all warm-blooded animals evolved from a single common ancestor driven by three objects of desire: lust, hunger, and security.

- Francis Galton: Known for his work in eugenics and behavioral genetics.