ONL Lab 3B.docx - ONL Lab 3B Introduction to the...

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ONL Lab 3B: Introduction to the brightfieldmicroscopeObjectivesAfter completing this exercise, you should be able to:Identify the various parts of the brightfield microscope and describe the correct way to use itDescribe some basic differences between wet mount and prepared (dry mount) microscope slidesPrelab Read the information and use it and the provided online resources to complete the Your Turn questions. Introduction to the Brightfield MicroscopeCytology is the study of cell structure and function. Because most cells are very small, they can only beseen when magnified with an instrument such as a microscope. Microscopes not only provide importantinformation about cell structure, they also provide clues about how the cell works.There are 2 basic types of microscopes: the light microscope (creates an image using a beam of light),and the electron microscope (creates an image using a beam of electrons.) The most common type oflight microscope, and the one you will use in this lab, is the brightfield microscope. The brightfieldmicroscope is an example of a compound microscope- light from the object you are viewing passesthrough two lenses before it reaches your eye.Microscopes not only magnify the object you are viewing, they also provide increased resolution, whichis the ability to distinguish two points as separate points. The better the resolution, the sharper the imageappears. The resolving power of the naked eye is approximately 0.2 mm, meaning that our eyes candistinguish two points that are 0.1 mm apart. A light microscope can improve resolution as much as 1000-fold! In addition, discernment of cellular detail can be improved with the use of dyes that add color andcontrast to small cellular structures.In this lab, you will learn about the different parts of the brightfield microscope, how to care for themicroscope, and the correct procedure for viewing specimens. You will then practice using themicroscope to view both a wet mount and a prepared (dry mount) slide of the eukaryotic organismEuglena. The diagram below shows some of the major parts of a brightfield microscope similar to the oneyou will be using in the lab:ACC BIOL 1406 Lab Manual Cypress Creek ONL Edition Lab 3Page 1
Parts of a brightfield microscope1.Base - The part of the microscope that rests on the table.2.Light Source – This is built into the base and is controlled by an on/off switch.3.Arm - A vertical support that connects the base to the body tube.4.Body Tube – The part of the microscope that connects the oculars with the revolving nosepiece. 5.Ocular lenses (Eyepiece Lens) - The lenses you look through to view a specimen. Somemicroscopes are monocularwith only one eyepiece to look through. Many microscopes are binocular,with two eyepieces, one for each eye. The magnification of the ocular lens will be marked on theeyepiece.

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