Cell Structure & Function

 Robert Hooke, 1665  Viewed cork, noted “cellulae” (monk’s cells)  Anton van Leeuwenhoek, 1676  First visualized “animalcules”  Theodore Schwann, Matthias Schleiden, 1830s  Described cell division, nuclei, all living things made of cells  Rudolf Virchow, 1858 & later  All cells arise from pre-existing cells

 Every living organism is composed of one or more cells  A cell is the smallest unit having the properties of life  The continuity of life directly arises from the growth and division of single cells

 Plasma membrane  Lipid bilayer  Regulates transport in/out of cell  Genetic material  Nucleus  Nucleoid  Cytoplasm

 Metabolic activity related to cell volume and surface area  Volume increases faster than surface area  The speed and amount of “stuff” (waste & nutrients) across a cell membrane is determined by the surface area  Larger cell volume needs more nutrients and produces more waste  Eventually the cell becomes big enough that the membrane can’t transport “stuff” fast enough

 Prokaryotes  Eukaryotes

 “Before the nucleus”—no nucleus or membrane-covered structures (organelles)  True bacteria  Archaebacteria  Very small  Simplest cells

 Nucleoid region  DNA (single loop)  Cell membrane  Cell wall (in some)  Capsule (in some)  Cytoplasm  Ribosomes  Pili  Flagellum

 Nucleus and other complex organelles  Organelle—internal membrane-bound compartment that serves specialized functions. “Little organs”  Protozoans  Algae  Fungi  Plants  Animals

 Complex systems

 Nucleus  Control center  Houses DNA (6 feet!!!)  Nuclear envelope/membrane Regulates transport of molecules Receptors for signaling  Nucleolus Constructs ribosomes

 Endoplasmic Reticulum (ER)  Rough Ribosomes attach Protein synthesis  Smooth No ribosomes Lipid synthesis

 Ribosomes  Synthesize proteins

 Golgi Bodies  Package and process proteins & lipids  Vesicles—sacs containing enzymes  Lysosomes—intracellular digestion  Peroxisomes—break down fatty acids & proteins  Vacuoles—large vesicles for storing food & water  Only some eukaryotes

 Mitochondria  Forms ATP (energy)  Requires oxygen  H+ stored in outer compartment, controlled flow into inner  Similar to bacteria: have their own DNA & ribosomes

 Plastids  Chlorloplasts—Photosynthesis (energy from light)  Chromoplasts—color  Amyloplasts—store starches  Central Vacuole  Storage (amino acids, sugars, ions, wastes)

 Centrioles—produce microfilaments during cell division.

 Cell membrane—regulates movement of “stuff” in and out of cell  Cell wall—strong, gives permanent shape to cell

 Protein filaments between nucleus & plasma membrane  Microtubules—keep organelles & cell structures in place or move them  Can fall apart in controlled ways (amoebas)  Some poisons can affect

 Microfilaments  Thin filaments  Help in cell division (contracts midsection)  Anchor membrane proteins  Muscle contraction

 Motor proteins move things within cells  Flagella—long outer structures for movement  Usually only a few  Cilia—short outer structures for movement  Usually many  Pseudopod  “False foot”

 Plant cells  Have cell walls & cell membranes  Have plastids such as chloroplasts  Have a central vacuole  Do not have centrioles  Animal cells  Have cell membrane but no cell wall  Do not have plastids  Do not have a central vacuole  Have centrioles