• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Microscopy Assignment (Molecular biology)

Extracts from this document...


Microscopy The website www.rifelabs.com/glossary.html defines microscopy as the science of studying a subject under a microscope, the subject being a minute object too small to otherwise be seen by the naked eye. The microscope is vital instrument in Cell Biology, since the human eye has a resolving power of 1/10 of a millimetre. Resolution The diameter of the ekaryotic cell varies from 10 - 30 �m (micrometers), and even smaller in the prokaryotic cells, this size is not visible by the naked eye, therefore microscopes are used to provide a better resolution. "Resolving power (resolution *) is the measure of the capacity to distinguish one another; it is the minimum distance that must be between two objects for them to be perceived as separate object." Magnification It is the number of times larger an image is compared with the real size of the object. It can be calculate using the formula below: Magnification = size of image . Actual size of specimen (1) The three types of microscopes are the light microscope, the transmission electron microscope and the scanning electron microscope. This assignment looks at the development and the differences of each microscope. ...read more.


They are then magnified by a series of magnetic lenses until they hit photographic plate or light sensitive sensors - which transfer the image to a computer screen. The image produced is called an electron micrograph (EM). The transmission electron microscope goes beyond the resolution of the light microscope and has been the main factor and instrument in assembling and gaining all the information about the cells and its organelles. The electron microscope uses electrons instead of light to produce a magnification of minute details with very high resolving power. Electrons allow the TEM to magnify in higher resolution because of their short wavelengths, in contrast to the light's longer wavelength. Because of these factors that Ernst Ruska considered when developing the TEM, the electron microscope can therefore magnify up to 500,000 times. Below is evidence of the detail the electron microscope can produce The Scanning Electron Microscope This new device was developed from the basis of the transmission electron microscope. Gerd Binnig and Heinrich Rohrer shared half of a Nobel Prize for their development of the scanning electron microscope. Differences Between Scanning Electron Microscope and Transmission Electron microscope. ...read more.


The short wavelength of electrons enables the electron microscope have high resolving power. However the electron has many disadvantages, as it costs over �1 million, and is also expensive to produce electron beam. It is large and bulky (refer to figure 1.3) and requires a special room. Finally, a vacuum is also needed to carry out the magnification. Below is a table summarising the above paragraphs. LIGHT MICROSCOPE ELECTRON MICROSCOPE Cheap to purchase (�100 - 500) Expensive to buy (over � 1 000 000). Cheap to operate. Expensive to produce electron beam. Small and portable. Large and requires special rooms. Simple and easy sample preparation. Lengthy and complex sample prep. Material rarely distorted by preparation. Preparation distorts material. Vacuum is not required. Vacuum is required. Natural colour of sample maintained. All images in black and white. Magnifies objects only up to 2000 times Magnifies over 500 000 times. (5) Reference: Figure 1.1: http://science.howstuffworks.com/light-microscope5.htm Figure 1.2: WS- Section A Molecules and Cells 3 Figure 1.3: http://www.phy.cuhk.edu.hk/centrallaboratory/CM120/CM120.jpg Figure 1.4: http://www.ogm-info.com/E.coli.jpg (1): (* Helena Curtis and N Sue Barnes 1989 Biology, The Fifth Edition W.H. Freeman, pages 94 - 99.) (2): (http://inventors.about.com/library/inventors/blmicroscope.htm) (3,4): http://www.mrothery.co.uk/cells/microscopynote.htm (5): Mary Jones, Richard Fosbery and Dennis Taylor (2000) Biology 1, Cambridge, Cambridge University Press, pages 3-10. ?? ?? ?? ?? ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Applied Science

    and water (H.OH). There are three main buffer systems within the body. 1. The Bicarbonate buffer system. The bicarbonate buffer system is presented in both intracellular and extracellular fluids, the bicarbonate ion (HCO3-) acts as a weak base, and carbonic acid (H2CO3)

  2. A Level Biology revision notes

    * Major site of daily glucose consumption (75%) is the brain via aerobic pathways * Most of the remainder is utilized by erythrocytes, skeletal muscle, and heart muscle * Glucose is obtained from diets or from amino acids and lactate via gluconeogenesis * Storage of glycogen in liver are considered to be main buffer of blood glucose levels

  1. Essay on microscopy. There are two types of electron microscope, transmission and scanning microscopes.

    Thin sections are mounted on copper grids which provide support. Sectioned tissue is stained by using heavy metals.

  2. Cell reasearch assignment

    of metabolic pathways Common metabolic pathways Organisms: Monera: Eubacteria and Archebacteria Organisms: Protists, Fungi, Plants and Animals Metabolism: anaerobic and aerobic; diverse Metabolism: mostly aerobic (http://www.carolguze.co.uk/1102-7-text-eukaryoticcells.shtml)

  1. Follicular development

    signalling pathway (Vanhaesebroeck and Alees, 2000), resulting in the activation of phosphoinositide-dependent kinases (PDK) -1 and -2, which subsequently leads to protein kinase B (PKB) phosphorylation and activation. In 2003, Zeleznik et al, determined that the presence of protein kinase B is essential in the stimulation of granulosa cell differentiation by FSH, which acts via the Gs?

  2. TB Assignment

    be infected by the mycobacterium TB, as the probability of being infected with the disease is proportional to the amount of time the droplet nuclei are exposed in the air. Therefore the risk is increased the longer that an uninfected person is in the company of an infected person.

  1. Biology Assignment

    For example, when the example, when the enzyme catalase is used to break down the hydrogen peroxide H202, to water and oxygen, the rate of reaction can be found by measuring the volume of oxygen given off in a known time.

  2. Technical documentation - Design specification.

    Data can also be entered in cells D14, D16 and D19 through input boxes. These input boxes are loaded when the buttons besides these cells are clicked. If the Friday Night Bonus button is pressed this input box would pop up.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work