Cellular Biology Notes

Cellular Level of Organization

  • Cell Membrane: Structure and Functions
  • Membrane proteins:
    • Integral proteins: Embedded in the membrane.
    • Channel proteins: Integral proteins that selectively allow particular materials to pass into or out of the cell.
  • Molecular Transport
    • Passive transport: Moves down the concentration gradient.
    • Active transport: Moves against the concentration gradient.
    • Osmosis: Diffusion of water.

Na/K Pump

  • Specific quantities of sodium and potassium molecules are involved (details not specified in the transcript).

Endocytosis

  • Two types:
    • Phagocytosis: Engulfment of large particles.
    • Pinocytosis: Ingestion of fluids or small particles.
    • Receptor-mediated endocytosis: Ligands bind to receptors, triggering vesicle formation.

Cell Organelles

  • Cytoplasm: Jelly-like substance containing organelles.
  • Endoplasmic Reticulum (ER): "Envelope" surrounding nucleus; lipid bilayer for transport, synthesizing, and storing materials.
    • Smooth ER: Synthesizes phospholipids, steroid hormones, regulates Ca++Ca^{++} concentration.
    • Rough ER: Contains ribosomes; involved in synthesis and modification of proteins destined for the cell membrane or export from the cell.
  • Golgi Apparatus: Sorts, modifies, and ships products from the rough ER.
  • Lysosomes: Break down and digest unneeded cellular components; perform autophagy (self-eating) and autolysis (apoptosis).
  • Mitochondria: "Energy transformer" of the cell. Formula for cellular respiration and its reverse process are implied but not specified.
  • Peroxisomes: Involved in lipid metabolism, chemical detoxification, and neutralizing free radicals.
  • Cytoskeleton: Critical for cell motility, cell reproduction, and transportation of substances within the cell.
  • Nucleus: Control center of the cell; stores genetic instructions for manufacturing proteins. Multinucleated muscle cells exist; RBCs lack nuclei.

DNA Replication

  • I - E - T: (Likely Initiation, Elongation, Termination - steps in DNA replication; not fully spelled out).

Protein Synthesis

  • Transcription: (DNA to mRNA).
  • Translation: (mRNA to protein).
    • Involves large and small ribosomal subunits, mRNA, tRNA, codons, anticodons, and amino acids.

Cell Cycle

  • PMAT: Prophase, Metaphase, Anaphase, Telophase (stages of mitosis).

Cell Differentiation and Stem Cells

  • Stem Cell:
    • Totipotent: Can differentiate into any cell type.
    • Pluripotent: Can differentiate into many cell types.
    • Multipotent: Can differentiate into a limited range of cell types.
  • Increasing cell specialization (differentiation) progresses from totipotent to pluripotent to multipotent stem cells.
  • Embryonic Stem Cells (ESC) or Pluripotent Stem Cells (PSC)
  • Three primary germ layers:
    • Ectoderm: Develops into neurons, glial cells, epidermis, retinal lens, pigment cells.
    • Mesoderm: Develops into odontoblasts, connective tissue, urogenital tissues, blood cells, skeletal muscle, adipose tissue.
    • Endoderm: Develops into pulmonary alveoli, thyroid gland, pancreatic cells, intestinal epithelium.