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Transcript
Ch.3 Cells The 3 Basic Parts of all Cells 1. Plasma Membrane 2. Cytoplasm • Entire contents of cell between P.M. and nucleus • . 3. Nucleus or Nuclear Area • Contains DNA, the genetic material – Phospholipids form a two-layer sheet Hydrophilic heads Water Hydrophobic tails Water Figure 5.11B Classes of Cells • Two basic types of cells: 1. Prokaryotic cells 2. Eukaryotic cells Prokaryotic cells are …. Prokaryotic cell Colorized TEM 15,000 Nucleoid region Nucleus Figure 4.3A Eukaryotic cell Organelles Prokaryotic Cell Pili Cell wall Plasma membrane Nuclear area Ribosomes Flagella Figure 4.3B Eukaryotic cells Animal Cell Fig 4.4A 1. The nucleus is the cellular control center Chromatin Nucleolus Nucleus Two membranes of nuclear envelope Pore Figure 4.5 Rough endoplasmic reticulum Ribosomes 2. Smooth endoplasmic reticulum, or smooth ER • Synthesizes lipids Smooth ER Rough ER Nuclear envelope Ribosomes Figure 4.7 Rough ER TEM 45,000 Smooth ER 3. Rough endoplasmic reticulum or Rough ER – Ribosomes on the surface Transport vesicle buds off 4 Ribosome 3 1 Secretory (glyco-) protein inside transport vesicle Sugar chain Figure 4.8 Polypeptide 2 Glycoprotein Rough ER 4. The Golgi apparatus finishes, sorts, and ships cell products Figure 4.9 “Receiving” side of Golgi apparatus Golgi apparatus Golgi apparatus New vesicle forming “Shipping” side of Golgi apparatus Transport vesicle from the Golgi TEM 130,000 Transport vesicle from ER 5. Vesicles: – Membrane-bound “balloons” that transport and store substances in cells 6. Lysosomes are sacs of enzymes • function in digestion within a cell • recycle damaged organelles Fig 4.13 •The various organelles of the endomembrane system are interconnected structurally and functionally 7. Mitochondria harvest chemical energy from food – Mitochondria carry out cellular respiration … Mitochondrion Outer membrane Intermembrane space Inner membrane Cristae Matrix TEM 44,880 Figure 4.14 8. Cytoskeleton & related structures Fig 4.17 Tubulin subunit Actin subunit Fibrous subunits 25 nm 7 nm Microfilament 10 nm Intermediate filament Microtubule – Microfilaments of actin – Intermediate filaments – Microtubules give the cell rigidity • And provide anchors for organelles and act as tracks for organelle movement Cilia and flagella move when microtubules bend Figure 4.18 LM 600 Colorized SEM 4,100 – Eukaryotic cilia and flagella are – Tight junctions – Anchoring junctions – Gap junctions • allow substances to flow from cell to cell Tight junctions Figure 4.18B Anchoring junction Gap junctions Extracellular matrix Space between cells Plasma membranes of adjacent cells Plant Cell – Fig. 4.6b Plant cells also have: 1. Vacuole • stores water, solutes, waste • Important for growth and rigidity 2. Chloroplasts 3. Cell wall **Plant cells do not have lysosomes Vacuoles function in the general maintenance of the cell Nucleus Chloroplast Colorized TEM 8,700 Figure 4.12 Central vacuole Chloroplasts convert solar energy to chemical energy – convert solar energy to chemical energy in sugars Chloroplast Stroma Granum Intermembrane space Figure 4.15 TEM 9,750 Inner and outer membranes Plant cells • have rigid cell walls made of cellulose Figure 4.22 Walls of two adjacent plant cells Vacuole Plasmodesmata Layers of one plant cell wall Cytoplasm Plasma membrane Chapter 5: How cells Work Transporting across membranes • Solvent – • Solute – – any molecule dissolved in the liquid. • Selectively permeable – water can move freely through the membrane, but the membrane regulates the passage of solutes • Diffusion – • Osmosis – movement of water across a selectively permeable membrane. Given a membrane that is permeable to water and glucose: Which way will water move? Which way will glucose move? • Hypertonic – high solute concentration, as compared to the other side of a membrane • Hypotonic – • Isotonic – equal solute concentrations on both sides of the membrane Fig. 5.12: Diffusion Isotonic Solutions Fig. 5.13 Fig. 5.14 Functions of membrane proteins Messenger molecule Receptor Activated molecule Enzymes Receptors for messages ATP Transport of substances Two types of transport across membranes 1. Passive transport (or Facilitated diffusion) – a solute moves through a membrane transport protein in the direction set by its concentration gradient – Small nonpolar molecules such as – Other larger or polar molecules do not easily diffuse across the bilayer and transport proteins provide passage across membranes through a process called facilitated diffusion Solute molecule Figure 5.15 Transport protein 2.Active transport • energy-driven transport proteins move solutes across membranes against their concentration gradient. • Why? • Mechanism: ATP binds to active transport pump, causing a change in its shape. The protein now has energy to pump the solute against its concentration gradient Cells expend energy for active transport Transport protein ATP Solute 1 Solute binding Figure 5.18 P ADP 2 Phosphorylation Protein changes shape 3 Transport P Phosphate detaches P 4 Protein reversion Exocytosis and endocytosis transport large molecules – To move large molecules or particles into the cell is endocytosis Figure 5.19A Fluid outside cell Vesicle Protein Cytoplasm