Overview
This lecture covers essential concepts in life and physical sciences for the ATI TEAS exam, focusing on biological organization, cell structure, genetics, biomolecules, infectious agents, disease transmission, and microscopy.
Levels of Biological Organization
- Life is organized into cells, tissues, organs, organ systems, and organisms.
- Cells are the basic unit of life found in all living organisms.
- Tissues consist of similar cells working together (e.g., cardiac muscle tissue).
- Organs are formed by different tissues working together (e.g., heart, lungs).
- Organ systems are groups of organs performing complex functions (e.g., digestive system).
- Organ systems together form an organism.
Cell Structure & Types
- Cell theory: all living things are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells.
- Two main cell types: prokaryotes (no nucleus, no membrane-bound organelles, e.g., bacteria) and eukaryotes (has nucleus and membrane-bound organelles, e.g., animals, plants).
- Common cell structures: cell membrane (selective barrier), cytoplasm (jellylike substance), cytoskeleton (support/movement), ribosomes (protein synthesis), nucleus (stores DNA), endoplasmic reticulum (processes/transport), Golgi apparatus (modifies/packages), mitochondria (ATP production), lysosomes (waste breakdown), vacuoles (storage).
Cellular Division: Mitosis vs. Meiosis
- Mitosis produces two genetically identical diploid cells (growth, repair).
- Meiosis produces four genetically unique haploid cells (gametes for reproduction).
- Mitosis: one division; meiosis: two divisions (meiosis I and II).
- Crossing over in prophase I of meiosis increases genetic diversity.
- Random assortment during meiosis leads to genetic variation.
Genetics & Heredity
- DNA contains genetic information in the form of genes, organized into chromosomes.
- Genes code for proteins; non-coding regions regulate gene expression.
- Chromosomes are long strands of DNA wrapped around proteins.
- Regulatory genes control expression of other genes.
- mRNA is transcribed from DNA and translated by ribosomes to make proteins.
- Types of RNA: mRNA (messenger), tRNA (transfer), rRNA (ribosomal).
- Protein synthesis: transcription (DNA to mRNA) occurs in nucleus; translation (mRNA to protein) occurs in cytoplasm.
Mendelian & Non-Mendelian Inheritance
- Traits are inherited via alleles (dominant and recessive forms).
- Punnett squares predict genotype and phenotype ratios for offspring.
- Monohybrid cross: one trait; dihybrid cross: two traits.
- Incomplete dominance: blended traits (e.g., pink flowers).
- Codominance: both traits expressed equally (e.g., speckled chickens).
Biomolecules: Types & Functions
- Carbohydrates: monosaccharide monomers, energy source, structural (cellulose/chitin).
- Lipids: hydrophobic, used for energy storage, membrane structure (phospholipids), insulation, some hormones.
- Proteins: made of amino acids, structural, enzymes, transport, immune defense, hormones.
- Nucleic acids: nucleotide monomers, store genetic info (DNA, RNA).
Infectious Agents & Disease
- Infectious agents: viruses (non-living, require host), bacteria (prokaryotes), fungi (eukaryotes, chitin cell wall), protozoa (unicellular eukaryotes), helminths (parasitic worms), ectoparasites (mites, fleas).
- Pathogenic means disease-causing; virulence is severity.
- Viruses replicate only inside host cells using host machinery.
- Bacteria may be gram-positive (thick wall) or gram-negative (thin wall, outer membrane).
Disease Transmission & Prevention
- Infectious diseases spread via direct contact (body fluids), droplet spread (cough, sneeze), airborne (dust, droplet nuclei), indirect/fomite (contaminated objects), or vector-borne (insects).
- Non-infectious diseases arise from genetics, environment, lifestyle (e.g., diabetes, heart disease).
Microscopy
- Magnification enlarges images; resolution distinguishes close objects.
- Light microscopes (bright-field/dark-field) for general use.
- Electron microscopes: TEM (internal structures), SEM (surface/external morphology).
Key Terms & Definitions
- Cell — Basic unit of life.
- Organelle — Specialized cell structure performing specific functions.
- Prokaryote — Cell without a nucleus or membrane-bound organelles.
- Eukaryote — Cell with a nucleus and membrane-bound organelles.
- Mitosis — Cell division producing identical diploid cells.
- Meiosis — Cell division producing genetically unique haploid gametes.
- Gene — Segment of DNA coding for a protein or trait.
- Allele — Variant form of a gene.
- Dominant/Recessive — Allele types; dominant expressed with one copy, recessive only if no dominant present.
- Monomer — Building block of macromolecules.
- Pathogen — Disease-causing agent.
- Vector — Organism (usually insect) transmitting disease.
Action Items / Next Steps
- Review textbook chapters on cell structure, genetics, and biomolecules.
- Practice Punnett squares and identify genotype vs. phenotype.
- Memorize biomolecule types, monomers, and functions.
- Complete assigned homework on disease transmission and microscopy.