BIOL 3510 1st Edition Lecture 1 Outline of Last Lecture Outline of Current Lecture I Introduction to cells II Microscopy III Prokaryotes and Eukaryotes IV Model Organisms Current Lecture Introduction to cells The simplest forms of life are solitary cells Higher organisms are communities of cells derived by growth and division from a single founder cell Therefore cells are the fundamental units of life Cell Theory Cells vary enormously in appearance and function All present day cells are believed to have evolved from an ancestral cell that existed more than 3 billion years ago The fundamental similarity of cells of all types makes it interesting to speculate on the origins of life 1 An amazing degree of similarity in the basic components that make up the inner workings of otherwise vastly different cells 2 Many metabolic pathways are conserved from one cell to another 3 The compounds that make up nucleic acids and proteins are the same in all living cells 4 Important proteins have closely similar detailed structures in prokaryotic cells and eukaryotic cells General Characteristics of a cell All cells grow convert energy from one form to another sense and respond to their environment and reproduce themselves All cells make use of the same types of biomolecules and all use energy All cells are enclosed by a plasma membrane that separates the inside of the cell from the environment All cells have an ability to maintain internal stability homeostasis These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute All cells contain DNA as a store of genetic information and use it to guide the synthesis of RNA molecules and of proteins Living Cells all have a similar basic chemistry All cells are composed of the same sorts of molecules that participate in the same types of chemical reactions Mutations are mistakes in the DNA that change the genetic plan from the previous generation and are the raw material for evolutionary change Discovery of Cells Better glasses lenses lead to the development of the microscope Hooke studied dead cork cells in 1665 Cell Biology was born after Schleiden in 1838 found that plants were made of cells and Schwann in 1839 who found the animals were made of cells also Schleiden and Schwann s Cell Theory all living things are formed by the division of existing cells Magnification is the enlargement of the physical appearance of something Resolution is the ability to distinguish two separate points 0 2mm is the minimum resolvable by the unaided eye Smaller needs light microscopy SEM or TEM Light Microscopy Resolution 0 2 micrometers Samples can be dead or alive Samples must be relatively transparent and thin Samples must contain contrast via staining or use of different optics Fluorescence Microscopy Resolution 0 2 micrometers Requires the use of two sets of filters The first filter narrows the wavelength range that reaches the specimen and the second blocks out all wavelengths that pass back up to the eyepiece except for those emitted by the dye in the sample Transmission Electron Microscopy TEM Resolution 2 nanometers Electrons and magnets are used to create and focus the image Dead samples are sectioned and stained with electron dense materials to create contrast Scanning Electron Microscopy Resolution 3 20 nanometers Heavy metal coated dead samples are scanned by an electron beam Pattern of electron scatter generates a 3D like image Summary of Types of Microscopy 1 Light microscopy allow examination of cells and some of their components a Bright field b Differential interference contrast c Fluorescence microscopy d Confocal fluorescence microscopy 2 Electron Microscopy allow examination of fine structures of cells a Transmission electron microscopy TEM b Scanning electron microscopy SEM Prokaryotes and Eukaryotes Prokaryote Greek derivation meaning before the nucleus Single celled organisms Is divided into two domains bacteria and archae The most diverse and numerous of cells on Earth No membrane bound organelles Cell wall contains peptidoglycan Size less than several micrometers Eukaryote Greek derivation meaning true nucleus Contain a well defined nucleus surrounded by a nuclear membrane Can be single celled such as yeasts and Paramecium or multi cellular such as animals and plants Membrane bound organelles No peptidoglycan if cell wall even present Size may be 10x larger Model Organisms Biologists cannot possibly study all living species Instead they have chosen a small number of model organisms reproduce rapidly are convenient for genetic manipulation others are multicellular and transparent so we can watch the development of all their tissues and organs ability to grow under controlled conditions Molecular biologists have focused on E coli Brewer s Yeast is a simple eukaryotic cell Arabidopsis has been chosen as a model plant Model animals include flies fish worms and mice Biologists also directly study human beings and their cells Comparing genome sequences reveals life s common heritage