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A View of the CellA View of the Cell
Unit #2Unit #2
The History of the Cell The History of the Cell TheoryTheory
Light microscopesLight microscopes Anton van Leeuwenhoek created Anton van Leeuwenhoek created
and used first simple light and used first simple light microscopemicroscope
Compound light microscope uses a Compound light microscope uses a series of lenses to magnify objectsseries of lenses to magnify objects
The History of the Cell The History of the Cell Theory (cont)Theory (cont)
Robert Hooke – used a compound Robert Hooke – used a compound light microscope to study cork; light microscope to study cork; looked like empty boxes or rooms looked like empty boxes or rooms so he called them cells after a so he called them cells after a monk’s roommonk’s room
The History of the Cell The History of the Cell Theory (cont)Theory (cont)
Matthias Schleiden observed plants; Matthias Schleiden observed plants; concluded that all plants are concluded that all plants are composed of cellscomposed of cells
Theodor Schwann observed Theodor Schwann observed different animal tissues; concluded different animal tissues; concluded that all animals are made of cellsthat all animals are made of cells
The Cell Theory of Modern The Cell Theory of Modern BiologyBiology
All organisms are made up of one All organisms are made up of one or more cells.or more cells.
The cell is the basic unit of The cell is the basic unit of structure, organization, and structure, organization, and function in an organism.function in an organism.
All cells come from preexisting All cells come from preexisting cells. (refers to life comes from life)cells. (refers to life comes from life)
Electron microscopesElectron microscopes
uses a beam of electrons instead of uses a beam of electrons instead of light to magnify structures light to magnify structures
specimens must be examined in a specimens must be examined in a vacuum because electrons will vacuum because electrons will collide/react with other atoms in the collide/react with other atoms in the airair
Electron microscopesElectron microscopes
Scanning Electron Microscope (SEM) Scanning Electron Microscope (SEM) used for 3D images of outside used for 3D images of outside structuresstructures
Transmission Electron microscope Transmission Electron microscope (TEM) used for images of inside (TEM) used for images of inside structures in the cellstructures in the cell
Two Basic Cell TypesTwo Basic Cell Types
Cells can be divided into two broad Cells can be divided into two broad groups based on whether or not groups based on whether or not they contain organelles.they contain organelles.
Organelles are specialized, Organelles are specialized, membrane-bound structures within membrane-bound structures within the cellthe cell
Two Basic Cell TypesTwo Basic Cell Types
Prokaryotic cells (prokaryotes) do Prokaryotic cells (prokaryotes) do not have organellesnot have organelles
Eukaryotic cells (eukaryotes) do Eukaryotic cells (eukaryotes) do have organelleshave organelles
The Plasma MembraneThe Plasma Membrane Homeostasis – maintaining stable Homeostasis – maintaining stable
conditions regardless of external or conditions regardless of external or internal factorsinternal factors
Plasma membrane is a flexible, Plasma membrane is a flexible, selectively permeable boundary selectively permeable boundary between the cell and its external between the cell and its external environmentenvironment
Selective permeability – allowing Selective permeability – allowing some materials to pass while some materials to pass while keeping others outkeeping others out
Structure of the Plasma Structure of the Plasma MembraneMembrane
Phospholipid bilayerPhospholipid bilayer Other components of the plasma Other components of the plasma
membrane aremembrane are
Phospholipid bilayerPhospholipid bilayer
Lipids, triglycerides, are composed Lipids, triglycerides, are composed of 3 fatty acid “tails” attached to of 3 fatty acid “tails” attached to Phospholipids Phospholipids
Phospholipid bilayerPhospholipid bilayer
Phospholipid divided into two areas: Phospholipid divided into two areas: the backbone or head is polar and the backbone or head is polar and “likes water”, the fatty acids are “likes water”, the fatty acids are nonpolar and are hydrophobic (fear nonpolar and are hydrophobic (fear water)water)
Polar ends face the outside and Polar ends face the outside and inside of the membraneinside of the membrane
Nonpolar tails face in like a Nonpolar tails face in like a sandwich sandwich
Fluid Mosaic ModelFluid Mosaic Model
the membrane is fluid because the the membrane is fluid because the phospholipids can move within the phospholipids can move within the membrane just as water moves membrane just as water moves with the currentwith the current
protein components are also protein components are also embedded in the membrane and embedded in the membrane and move, creating a pattern or mosaicmove, creating a pattern or mosaic
Other components of the Other components of the plasma membraneplasma membrane
Cholesterol – steroid – stabilizes Cholesterol – steroid – stabilizes membrane by keeping the fatty acids membrane by keeping the fatty acids from sticking togetherfrom sticking together
Transport proteins or membrane-Transport proteins or membrane-spanning proteins – span entire spanning proteins – span entire membrane and create channels or membrane and create channels or carrier molecules for certain substances carrier molecules for certain substances to enter and leave the cellto enter and leave the cell
Integral proteins – are embedded in Integral proteins – are embedded in either the inside layer or the outside either the inside layer or the outside layer; they play a role in cell layer; they play a role in cell identification and attaching structures identification and attaching structures to the cell membraneto the cell membrane
Plasma MembranePlasma Membrane