Overview
This lecture provides a comprehensive summary of foundational biology topics, from characteristics of life and cell structure to genetics, evolution, classification, ecology, and human body systems.
Characteristics of Life & Levels of Organization
- Life is hard to define and exceptions exist, but common characteristics include cellular organization, metabolism, growth, response to stimuli, and reproduction.
- Cell theory states all living things are made of cells, cells are the smallest living units, and all cells arise from pre-existing cells.
- Levels of biological organization: cell → tissue → organ → organ system → organism → population → community → ecosystem → biome → biosphere.
Biomolecules & Enzymes
- Four major biomolecules: carbohydrates (monosaccharides), lipids (fatty acids & glycerol), proteins (amino acids), and nucleic acids (nucleotides).
- Enzymes are proteins with an active site where substrates bind, speeding up chemical reactions.
- Enzymes function best within specific temperature and pH ranges; outside these ranges, they may denature.
Cells: Types and Structure
- Prokaryotes (bacteria, archaea) lack a nucleus and membrane-bound organelles; eukaryotes (plants, animals, fungi, protists) have both.
- Both cell types have DNA, cytoplasm, ribosomes, and a cell membrane.
- The cell/plasma membrane controls homeostasis by regulating substance movement (passive and active transport).
- Osmosis is the movement of water across membranes toward higher solute concentrations.
Cellular Processes: Respiration, Photosynthesis, and DNA
- Cellular respiration (mitochondria): breaks down glucose to make ATP; can be aerobic or anaerobic.
- Photosynthesis (chloroplasts): uses sunlight to produce glucose; reactants/products are generally inverses of respiration.
- DNA is made of nucleotides (phosphate, deoxyribose, nitrogenous base); bases pair (A-T, C-G).
- DNA replication is semi-conservative, involving enzymes like helicase, primase, DNA polymerase, and ligase.
Cell Cycle, Mitosis, and Meiosis
- Cell cycle: G1 (growth), S (DNA synthesis), G2 (prep), M (mitosis/cytokinesis); regulated by proteins and checkpoints.
- Mitosis produces identical diploid body cells; mnemonic PMAT for stages.
- Meiosis produces four unique haploid gametes by two consecutive divisions, allowing recombination via crossing over (prophase I).
Genetics: Inheritance and Variation
- Alleles are forms of a gene; dominant alleles mask recessive ones.
- Mendelian crosses use Punnett squares to predict genotype/phenotype ratios.
- Non-Mendelian inheritance includes incomplete dominance, codominance, sex-linked traits, and multiple alleles.
- Pedigrees trace inheritance patterns; symbols indicate sex and affected status.
Protein Synthesis & Mutations
- Protein synthesis: transcription (mRNA in nucleus) and translation (at ribosome).
- tRNA matches mRNA codons with amino acids, building polypeptide chains.
- Mutations: substitutions, insertions, deletions—insertions/deletions may cause frameshifts.
Evolution: Mechanisms and Selection
- Natural selection favors traits increasing reproductive success; genetic drift involves random changes (bottleneck, founder effects).
- Mutations, independent assortment, and crossing over create genetic diversity.
Classification of Living Things
- Three domains: Bacteria, Archaea, Eukarya.
- Taxonomic hierarchy: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.
- Scientific names (binomial nomenclature) are more standardized than common names.
Kingdoms & Plant Biology
- Plants are autotrophs, performing photosynthesis in chloroplasts; vascular plants have xylem/phloem, nonvascular get water by osmosis.
- Stomata are pores for gas exchange, controlled by guard cells.
- Flowering plant reproduction involves pollination and double fertilization, producing seeds and fruit.
Ecology: Food Chains, Cycles, and Succession
- Energy flows from producers to consumers; only ~10% energy transfers per trophic level.
- Food webs show interconnections and biodiversity's role in stability.
- Ecological succession: primary (new area, no soil, pioneer species) and secondary (soil remains after disturbance).
- Biogeochemical cycles: carbon and nitrogen cycles show matter recycling; bacteria play key roles.
Ecological Relationships & Human Systems
- Predation, competition, and symbiosis (commensalism, parasitism, mutualism) define organism interactions.
- Eleven human body systems work together to maintain function and respond to stimuli.
Key Terms & Definitions
- Homeostasis — maintenance of stable internal conditions.
- Osmosis — movement of water across a membrane toward higher solute concentration.
- Enzyme — protein that catalyzes biochemical reactions.
- Allele — a variant form of a gene.
- Phenotype — observable traits of an organism.
- Genotype — genetic makeup of an organism.
- Mitosis — cell division producing identical body cells.
- Meiosis — cell division producing haploid gametes.
- Photosynthesis — process converting sunlight to chemical energy.
- Cell Cycle — ordered sequence of events in cell division.
- Symbiosis — close relationship between different species.
Action Items / Next Steps
- Review specific videos on complex topics (genetics, viruses, classification, plant reproduction, ecological cycles).
- Use provided mnemonics for memorizing classification levels and biomolecule elements.
- Practice drawing and labeling cell structures, flower anatomy, and energy pyramids.
- Complete assigned readings and exercises on recent lessons as directed by your instructor.