Cell Structure

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Flashcards on Cell Structure, created by zikra_98 on 24/12/2014.
zikra_98
Flashcards by zikra_98, updated more than 1 year ago
zikra_98
Created by zikra_98 almost 10 years ago
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Question Answer
Define Magnification The degree to which the size of an image if larger than the object itself
Define resolution The degree to which it is possible to distinguish between two objects
How does a light microscope work? -Light passes from a bulb under the stage, through the condenser lens then through the specimen -A beam of light is focused through the objective lens, then through the eyepiece lens.
How does sectioning work? -Specimens are embedded in wax -Thin sections are cut w/o distorting the structure of the specimen -useful for making sections of soft tissue e.g. brain
How does a Transmission Electron Microscope (TEM) work? -electron beam passes through a very thin sample -electrons pass through the denser parts of the sample less easily - gives contrast -Image is 2D -Magnification - 500 000x
How does a Scanning Electron Microscope (SEM) work? -electron beam is directed onto a sample -electrons bounce off sample -image is 3D -magnification - 100 000x
Advantages of an electron microscope -Electron beams are deflected by molecules in the air - need to be in a vacuum -v. expensive -Preparing samples/using microscope require skill and training
Define Ultrastructure Detailed structure of the internal components of cells revealed by electron microscopes
What is a cytoskeleton? A network of fibers made of protein
What are microtubles? -Made of tubulin -How vesicles move from the ER to the GA
What are microfilaments? -Made of actin -Found beneath the cell membrane -Involved in muscle cell contraction/WBC -helps some organelles move around cell
What are intermediate filaments? Structural components of the nuclear envelope
What are flagella and cilia? Hair like structures on the surface of cells. Made up of a cylinder that contains 9 microtubules on the outer edge and 2 in the middle. Use ATP
What is flagella? -Found in prokaryotes -made of flagellin -occur in ones or twos
What is undulipodia? Found in eukaryotes Made of microtubules Occur in ones or twos
What is Cilia? -move together in a sweeping movement -occur in large numbers
What is the cell size of eukaryotic and prokaryotic cells? 10-100um and 1-10um respectively
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