Transcript Document
Cells The 3 Basic Parts of all Cells 1. Plasma Membrane • Controls what enters & exits the cell 2. Cytoplasm • Entire contents of cell between P.M. and nucleus • Where most metabolic activity occurs 3. Nucleus or Nuclear Area • Contains DNA, the genetic material – Phospholipids form a two-layer sheet • Called a phospholipid bilayer, with the heads facing outward and the tails facing inward 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 structurally simpler than eukaryotic cells 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 • Containing the cell’s DNA, which directs cellular activities 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 • Processes toxins and drugs in liver cells • Stores and releases calcium ions in muscle cells 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 • Produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles 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 – Stacks of membranous sacs receive and modify ER products then ship them to other organelles or the cell surface 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 • Lysosomes in white blood cells destroy bacteria that have been ingested • 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 which uses the chemical energy in food to make ATP for cellular work Mitochondrion Outer membrane Intermembrane space Inner membrane Cristae Matrix TEM 44,880 Figure 4.14 8. Cytoskeleton & related structures • a network of protein fibers • help organize its structure and activities Fig 4.17 Tubulin subunit Actin subunit Fibrous subunits 25 nm 7 nm Microfilament 10 nm Intermediate filament Microtubule – Microfilaments of actin • Enable cells to change shape and move – Intermediate filaments • Reinforce the cell and anchor certain organelles – 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 locomotor appendages that protrude from certain cells – Tight junctions • can bind cells together into leakproof sheets – Anchoring junctions • link animal cells into strong tissues – 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 Please do the activities at the following 2 sites: http://learn.genetics.utah.edu/conte nt/begin/cells/insideacell/ http://learn.genetics.utah.edu/conte nt/begin/cells/scale/ Plant Cell – Fig. 4.6b Plant cells also have: 1. Vacuole • stores water, solutes, waste • Important for growth and rigidity 2. Chloroplasts • Site of photosynthesis: conversion of light to ATP which drives formation of sugars 3. Cell wall • Protects, supports **Plant cells do not have lysosomes Vacuoles function in the general maintenance of the cell – lysosomal and storage functions Nucleus Chloroplast Colorized TEM 8,700 Figure 4.12 Central vacuole Chloroplasts convert solar energy to chemical energy – found in plants and some protists – 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 • Are connected by plasmodesmata - connecting channels Figure 4.22 Walls of two adjacent plant cells Vacuole Plasmodesmata Layers of one plant cell wall Cytoplasm Plasma membrane