Chapter 4- A View of the Cell

4.1-The Discovery of Cells Cells are the basic units of living organisms Development of the microscope allowed scientists to view cells

Cell Theory 1665-Robert Hooke Uses compound microscope to observe cork Hollow boxes…..CELLS!! 1830s-Schleiden and Schwann Schleiden-all plants are composed of cells! Schwann-all animals are composed of cells!

Three Parts of Cell Theory 1. All organisms composed of one or more cells. 2. Cell is the basic unit of organization of organisms. 3. All cells come from preexisting cells.

History of the Microscope 1665-Hooke’s Microscope Three lenses Poor Quality Little detail

1700-Anton van Leeuwenhoek Built over 240 microscopes! Single Lens Better Quality Observed red blood cells & bacteria Mid 1800s-Compound Light Microscope Series of lenses Light passes through object then lens More detail

1940s-Electron Microscopes Beam of electrons through magnetic field Specimen in vacuum Only view dead cells or organisms 1.SEM-Scanning Electron Microscope Surface of specimen-3D Picture! 2.TEM-Transmission Electron Microscope Through the specimen Magnify 100s or 1,000s of times! 3.STM-Scanning Tunneling Microscope Arrangement of atoms on surface Map hills and valleys

Basic Cell Types… Look at internal organization! Prokaryotes-lacks internal structures Eukaryotes-membrane bound, internal structures. Structures called organelles Largest organelle = NUCLEUS!

Section 4.2-Eukaryotic Cell Structure Must have boundaries! Plasma Membrane Boundary between cell & environment Flexibility Controls movement of materials Cell Wall-only plant cells! Rigid, surrounds membrane Thicker, stronger network for structural support

Fluid-Mosaic Membrane

GET UNDER CONTROL!!!! Nucleus-contains cell’s DNA, manages cell function Surrounded by nuclear envelope Double membrane-pores allow movement Chromatin-long strands of DNA Packed into chromosomes

Nucleus

Nucleolus Region inside nucleus Produces particles for protein synthesis Particles are called ribosomes Cell assembles enzymes according to DNA Not bound by membrane

Nucleolus

Assembly, Transport, & Storage Cytoplasm-outside nucleus, surrounds organelles Clear liquid Important chemical reactions (protein assembly) take place here Endoplasmic Reticulum (ER)- Network of interconnected compartments Surface folded into cell Tissues in a box! Site for lipid synthesis in cell

Smooth or Rough? Smooth ER Rough ER ER acts as cell’s delivery system! Lacks ribosomes on surface Rough ER Studded with ribosomes on surface ER acts as cell’s delivery system!

Structures for Storage Golgi Apparatus Closely stacked, flattened membrane sacs Receives proteins and lipids Modifies them chemically, repackages Distributes them throughout membrane Vacuole-sac of fluid Temporary storage of food, enzymes etc. Animal cell-small and numerous Plant cell-single large vacuole for water

Golgi Apparatus Vacuole

Reduce, Reuse, RECYCLE! Lysosomes Digest excess or worn out cell parts, food particles, and invading viruses/bacteria Membrane protects digestive enzymes from rest of cell

Energy Transformers Mitochondria Break down food-convert to energy! Peanut-shaped Highly folded inner membrane for more energy storage Chloroplasts-plants only! Transform light energy into chemical energy Chlorophyll-traps energy from sun Green color!

NRG!!

Support and Locomotion Cytoplasm 1. Cytoskeleton-network of fibrous elements Act as scaffold for organelle support 2. Microtubules-thin, hollow cylinders Made of protein 3. Microfilaments-thin, solid fibers Both make up most of cytoskeleton

LET’S GET MOVING! Cilia Flagella Short, numerous hair-like projections On cell’s surface Movement like “the wave!” Flagella Longer projections Whip-like motion One or two per cell

Flagella vs Cilia

Cellular Organization 1. Single-celled organisms: Unicellular 2. Many-celled organisms: Multicellular 3. Cells functioning together for activity: Tissues 4. Two or more tissues functioning together: Organs 5. Organs working together to carry out major life functions:Organ System