Microscopy and Discovery of the Cell PDF

MICROSCOPY AND DISCOVER Y OF THE CELL © Copyright 2015 – All rights reserved. LEARNING OBJECTIVES: At the end of the lesson, the learners should be able to: 1. trace the development of the microscope, and 2. enumerate the tenets of the cell theory. THE EARLY MICROSCOPY © Copyri...

MICROSCOPY AND DISCOVER Y OF THE CELL © Copyright 2015 – All rights reserved. LEARNING OBJECTIVES: At the end of the lesson, the learners should be able to: 1. trace the development of the microscope, and 2. enumerate the tenets of the cell theory. THE EARLY MICROSCOPY © Copyright 2015 – All rights reserved. In 1590s, Hans Janssen and Zacharias Janssen, two Dutch eye glass makers:  Discovered that the combination of two lenses in a particular arrangement was the secret to a better visualization and magnification of objects. One lens was positioned at the eyepiece. Second lens was put near the sample. 2 feet long and extremely heavy. 17TH-CENTUR Y MICROSCOPES © Copyright 2015 – All rights reserved. ROBERT HOOKE English Scientist o Used the compound microscope to observe cork. o Hooke observed that cork is composed of small, hollow compartments. o The parts prompted Hooke to think of small rooms (cells) in a monastery, so he gave them the same name: CELLS. o Investigated cork through experimenting with the compound microscope and came up with the name cells! Key Note: Hooke discovered the cell in 1665, which started formulating CORK MONASTERY © Copyright 2015 – All rights reserved.  HOOKE’S INVESTIGATION/EXPERIMENT Hooke’s Observations Hooke’s Microscope © Copyright 2015 – All rights reserved. ANTON VAN LEEUWENHOEK Dutch Tradesman o Study new approaches for creating lenses to observe cloth. o Leeuwenhoek’s microscope was more powerful than Hooke’s compound microscope. o From investigating and experimenting with his microscope, Leeuwenhoek (1676) became one of the first scientists to refer to living cells when he observed an abundant number of single- celled organisms, which he called animalcules (plant & animal), swimming in a drop of pond water! © Copyright 2015 – All rights reserved.  LEEUWENHOEK’S INVESTIGATIONS/EXPERIMENT Leeuwenhoek’s Leeuwenhoek’s Observations Microscope © Copyright 2015 – All rights reserved.  He figured how to grind glass together and decided to experiment. Leeuwenhoek made his own 270x magnification compound microscope! Today, microscopes magnifications range from 200x-10,000,000x magnification.  ROBERT In 1831 he was able to BROWN compare diverse kinds of plant specimens under the microscope. Indicated that there is a common thing about them- they are all composed of cells, and inside the cell is a dark dense spot which he termed as the NUCLEUS. MATTHIAS SCHLEIDEN German Scientist oFascinated with plant cells, Schleiden (1838) used the compound microscope and studied plant cells. oFrom investigating and experimenting with plants, projected plant parts are made of cells! oDiscussed what he observed with his dear friend, German scientist Theodor Schwann. © Copyright 2015 – All rights reserved. THEODOR SCHWANN German Scientist oStudied plant & animal cells, and was intrigued by the similarities between the two. oFrom investigating and experimenting with plant & animal cells, Schwann ( 1839) was able to determine that all © Copyright 2015 – All rights reserved. RUDOLF VIRCHOW oIn 1858, based on his investigations and experiments, he stated “omnis cellula e cellula” which means that all cells come from cells. © Copyright 2015 – All rights reserved.  CELL THEOR Y © Copyright 2015 – All rights reserved.  CELL THEOR Y There are 3 major parts of the cell theory: 1. All organisms are made of cells. 2. All existing cells are produced by other living cells. 3. The cell is the most basic unit of life. © Copyright 2015 – All rights reserved.  MICROBIOLOGY Robert Koch German Physician and Microbiologist Discover two infectious bacteria, tubercle and  ELECTRON MICROSCOPES © Copyright 2015 – All rights reserved. © Copyright 2015 – All rights reserved.  Around 1930, a Hungarian physicist named Leo Szilard designed the electron microscope. However, Szilard did not build the microscope.  In 1931, Ernst Ruska and Max Knoll built the first electron microscope that could magnify at 400x. In 1933, Ruska built another electron microscope that was more powerful than any other compound microscope at that time. These powerful electron microscopes allowed scientists to study pieces and processes inside cells that they could not see before.  Uses beams of accelerated electrons as a source of illumination. Uses electrostatic and electromagnetic lenses in forming the image by controlling the electron beam to focus it at a specific plane with reference to the specimen. MICROSCOPE  MICROSCOPE Microscopes are instruments that are used in science laboratories to visualize very minute objects such as cells, and microorganisms, giving a contrasting image that is magnified. STRUCTURAL PARTS OF A MICROSCOPE AND THEIR FUNCTIONS  THERE ARE THREE STRUCTURAL PARTS OF THE MICROSCOPE 1. Head – This is also known as the body. It carries the optical parts in the upper part of the microscope  THERE ARE THREE STRUCTURAL PARTS OF THE MICROSCOPE 2. Base – It acts as microscopes support. It also carries microscopic illuminators  THERE ARE THREE STRUCTURAL PARTS OF THE MICROSCOPE 3. Arms – This is the part connecting the base and to the head and the eyepiece tube to the base of the microscope. OPTICAL PARTS OF A MICROSCOPE AND THEIR FUNCTIONS  1. EYEPIECE also known as the ocular. This is the part used to look through the microscope. Its found at the top of the microscope. Its standard magnification is 10x with an optional eyepiece having magnifications from 5X to 30X.  EYEPIECE TUBE it’s the eyepiece holder. It carries the eyepiece just above the objective lens. In some microscopes such as the binoculars, the eyepiece tube is flexible and can be rotated for maximum visualization, for variance in distance. For monocular microscopes, they are none flexible.  NOSE PIECE also known as the revolving turret. It holds the objective lenses. It is movable hence it can revolve the objective lenses depending on the magnification power of the lens. PARTS OF A MICROSCO PE  STAGE This is the section in which the specimen is placed for viewing. They have stage clips that hold the specimen slides in place. The most common stage is the mechanical stage, which allows the control of the slides by moving the slides using the mechanical knobs on the stage instead of moving them manually.  THE RACK STOP It controls how far the stages should go preventing the objective lens from getting too close to the specimen slide which may damage the specimen. It is responsible for preventing the specimen slide from coming too far up and hitting the objective lens.  THE ADJUSTMENT KNOBS These are knobs that are used to focus the microscope. There are two types of adjustment knobs i.e fine adjustment knobs and coarse adjustment knobs.  FINE ADJUSTMENT KNOB It is the smaller knob, which is used for sharp and fine focusing of the object. For accurate and sharp focusing, this knob can be used.  COARSE ADJUSTMENT KNOB It is a large knob that is used for moving the body tube down and up for bringing the object to be examined under exact focus.  OBJECTIVE LENSES These are the major lenses used for specimen visualization. They have a magnification power of 40x-100X. There are about 1- 4 objective lenses placed on one microscope, in that some are rare facing and others face forward. Each lens has its own magnification power. Oil immersion objective – 100X High power objective – 45X Low power objective – 10X MICROSCOPIC ILLUMINATOR This is the microscopes light source, located at the base. It is used instead of a mirror. It captures light from an external source of a low voltage of about 100v.  DIAPHRAGM primary role is to control the amount of light that reaches the specimen. It’s an adjustable apparatus, hence controlling the light intensity and the size of the beam of light that gets to the specimen. For high-quality microscopes, the diaphragm comes attached with an Abbe condenser and combined they are able to control the light focus and light intensity that reaches the  CONDENSER These are lenses that are used to collect and focus light from the illuminator into the specimen. They are found under the stage next to the diaphragm of the microscope. They play a major role in ensuring clear sharp images are produced with a high magnification of 400X and above. The higher the magnification of the condenser, the more the image clarity. More sophisticated microscopes come with an Abbe condenser that has a high magnification of about 1000X.  ABBE CONDENSER this is a condenser specially designed for high-quality microscopes, which makes the condenser to be movable and allows very high magnification of above 400X. High-quality microscopes normally have a high numerical aperture than objective lenses.  CONDENSER FOCUS KNOB this is a knob that moves the condenser up or down thus controlling the focus of light on the specimen.  APERTURE This is a hole on the microscope stage, through which the transmitted light from the source reaches the stage. MAINTENAN CE OF MICROSCOP ES USING THE MICROSCOPE: 1. Ensure that the microscope is one fist away from the edge of the table. 2. Make sure that you have sufficient source of light, or the switch is on. 3. When adjusting the focus, lower the objective lens down as far as it will go. However, you should never allow the lens to touch the slide you are looking at. 4. Never touch the bulb. AFTER USING THE MICROSCOPE: 1. Turn off the illuminator and wait for it to cool for several minutes before putting it away. 2. When turning off (and on) the microscope, use the switch not the power socket. CARRYING THE MICROSCOPE: 1. Always lift the microscope with two hands: one hand on the arm, the other hand supporting the base. 2. Do not pick it up by the stage, as this can cause misalignment. 3. When transporting it use a microscope bag. 4. Handle it with utmost care. CLEANING THE MICROSCOPE: 1. Dust should be cleaned off with pressurized air or with soft brush. 2. Use only lens paper and lens cleaner. STORING THE MICROSCOPE: 1. Cover when not in use. 2. Store in a clean, dry place. 3. In humid or moist environments, it is advisable to store the microscope in a waterproof container. 4. Do not store in direct sunlight.