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INTRODUCTION TO CELL BIOLOGY E. D. Salmon - Biology 205 1. Organization: • 2 part course, 2 instructors • 4 exams, 4 count, all exams scaled, • recitations run by TA’s, material covered in lecture exams • problem questions for recitations, similar questions on exams 2. Book • : Essential Cell Biology, Alberts et al., 2nd edition (2004) 3. Scope of Course: • Theme: Molecular Organization ----> Structure ----> Function • Significant molecules in cells, their general structure and function • Major cell structural features • How structure determines function • Biochemistry-only identification of major molecules and forces which drive reactions and determine structure 4. Cell Unity and Diversity: A. Cell Theory: Cells are units of life; they all have: • Delimiting plasma membrane to separate inside from outside • Metabolism to generate complex molecules from foodstuffs and energetic molecules from light (photosynthesis) or from respiration • Capacity for reproduction • genes --> transcription --> translation --> structure and regulation • (DNA) --> mRNA --> proteins --> subunits and enzymes All cells share the same "central dogma": (how they create essential components for life from their genetic code) DNA TRANSCRIPTION mRNA TRANSLATION Protein All cells share the same information code 0 and 1 A, G, C, and T GENOME = entire collection of genes for an organism Genome size varies based on the complexity of the organism: Mycoplasma: 477 genes E.coli: 4289 genes Budding Yeast: ~6300 genes Fruit Fly: ~14,000 genes Chimpanzee: ~30,000 genes Human: ~30,000 genes B. Unity: • Common biochemistry-small molecules, macromolecules and linkers (see Biochemistry Handout) • Common supramolecular structures and physiology - e.g., lipid bilayers, ribosomes C. Diversity: • 2 major classes of cells based on complexity of intracellular organization: • 1) Procaryotes (no nuclear envelope) Single cell • 2) Eucaryotes (nuclear envelope) Protista, Fungi, Plants, Animals; single cell and multicellular; cell differentiation, specialization and intercellular communication 5. Viruses (are NOT cells): • 20-300nm size • DNA (RNA) + protein capsule • not cells but highly specialized parasites; specific for host cell • gene 1 kbase, several proteins for coat, infection and control of host metabolism • diversity of form-rods, icosahedron, phage 6. Procaryotes: Mycoplasma, bacteria and blue-green algae A. Mycoplasma are simplest cells • 1) 100nm in size • 2) DNA-750 kb; 500-1000 different proteins • 3) Produce disease in animals and plants - e.g., pleuropneumonia B. Bacteria: Simple structure but complex biochemistry • 1) 1-10 m typically • 2) 3000kb, DNA 1mm long; several thousand different proteins • 3) Cell cycle = 20 min in nutrient media • 4) Metabolism diverse: aerobic, anaerobic, nitrogen fixation, sulfur, severe environment, photosynthetic, spores • 5) General bacterial structure: 6) Special Features: • Respiration produces ATP and proton gradient across PM • PM provides selective transport • Bacteria containing bacteriochlorphyll do photosynthesis in membrane sacs enfolded from the PM • Motility produced by rotary engine in plasma membrane rotating stiff helical bacterial flagella (flagellin) • DNA not complexed with proteins 6) Special Features (cont): • Ribosomes similar but distinct from eukaryotic ribosomes • DNA structure and ribosomes similar to those in mitochondria and chloroplasts • Cell division by fission, Mesosome structure involved C. Blue-green algae (cyanobacteria) • 1) photosynthetic; contain unique pigments, the phycobilins-phycocyanin (blue) and phycoerythin (red) plus chlorophyll a • 2) Fix CO2 and N2 into organic molecules • 3) Evolution of electron source: H2S --> H2O: O2 7. Eucaryotes • Complex structure, complex biochemistry many functions and biochemical processes compartmentalized within membrane bound organelles; uni and multicellular organisms, specialization and differentiation. A. Function of major structures and organelles (Animals and Plants): • Plasma membrane: selective transport, receptors, connectors • Nucleus- DNA complexed with histones; double membrane with pores • SER: lipid synthesis; calcium regulation • Ribosomes in cytosol- synthesis of proteins • RER: site protein synthesis for secretion • Golgi: glycosylation, packaging for secretion • Lysosomes: digestion Function of major structures and organelles (Animals and Plants): • Coated vesicles: endo and exocytosis • Mitochondria: aerobic respiration; own DNA and ribosomes like a bacteria; double membrane • Intercellular junctions: gap, tight, desmosomes or plasmadesmada • Extracellular matrix: ex. glycocalyx (animals) or cellulose (plants) • Cytoskeleton (actin-myosin, microtubules, intermediate filaments): cell motility, organelle transport, cell morphogenesis and cell division B. Plants (vs animal) cell structure: • Rigid cell wall • Cells do not move, but exhibit vigorous cytoplasmic streaming • Chloroplasts and other plastids: photosynthesis; own DNA and ribosomes; double membrane C. Cell specialization and differentiation: • Protozoa, Yeast • Multicellular organisms