Investigating cells with a light microscope

• Organisms are made up of cells, most of which are specialised to do a particular job.
• Microscopes are needed to study cells in detail.
• The limits of the light microscope can be overcome by using electron microscopy.
• Animal cells and plant cells can be investigated using a light microscope.
• Once slides have been prepared, they can be examined under a microscope.
• The aim of the experiment is to use a light microscope to examine animal or plant cells, make observations and draw scale diagrams of cells.
• The method involves rotating the objective lenses so that the low power, eg x10, is in line with the stage, focusing the slide towards you by turning the coarse focus adjustment, placing the slide on the stage, re-focusing the slide using the fine focus adjustment, and recording an image.
• Care must be taken when looking down the microscope if the illumination is too bright, using microscope stains, and handling coverslips and microscope slides.
• The experiment can be repeated with different slides, and the microscope images can be recorded using labelled diagrams or produced digital images.
• When first examining cells or tissues with low power, draw an image at this stage, even if going on to examine the slide with high power.
• A low power diagram is used as a plan to show the arrangement of any distinct regions of the tissue, and a high power diagram is then produced – a detailed image of a part of the slide.
• The high power diagram is usually drawn to show a single cell, for example of a single cheek cell or onion cell.