Microscopy
The technical use of microscopes to view and observe objects and specimens that cannot be seen by the naked human eye is called microscopy.
- To study cells, their structure, and composition and to understand the molecular nature of cells and life components, scientists faced a major problem that the cells were of very small dimensions and transparent.
- The human eye could not see them, magnify, or distinguish the minute particles.
Microscope:
A microscope is an instrument that has high magnification and resolving power than the human eye, to look at smaller objects and produce an image that shows the object larger. These images produced by microscopes are called micrographs. Magnification is the method in which the image of the object is increased in size so the retina is stimulated to send an impulse allowing the object to be perceived.
Microscopes are of different types. The magnifying glasses or microscopes having only one lens are called simple microscopes. Microscopes that have an eyepiece and lens are called compound microscopes. In biological studies, two types of microscopes are used most extensively.
Light Microscope:
The optical microscope uses visible light and a system of lenses for illuminating and magnifying the images of small objects. These types of optical microscopes are the old designs of microscopes. Light microscopes are cheap and easy to purchase and simple to use. light microscopes show the natural colors of the specimen. Contrary to that, they have very restricted magnification only up to 1500X. They lack in-depth field.
Parts of light Microscope:
The light microscope consists of an eyepiece, objective lens, condenser lens, stage, fine focus, base, and table.
Light microscopes use transparent, relatively small, spare, and thin specimens. These are best to see mitochondria, most bacterial types, microvilli, etc as they have magnification up to 1200X.
Electron microscopy
The technique used to get high-resolution images of biological specimens and non-biological objects. The purpose of electron microscopy is to study, understand and research the structure, composition, shape, size of cells, tissues, or other non-living micro-entities.
Electron microscopy works with a much shorter wavelength to attain resolution as low as 3 Aᵒ with usually ranging from 5 to 12 Aᵒ.
Principle of Working:
An electron microscope uses an electron beam accelerated from heated metal wire by high voltages from 20,000 to 100,000 volts to generate an image of an object and magnification of an object is done by electromagnetic fields in which light waves are used to generate an image and magnification is get by optical lenses.
Electron microscope functions under vacuum that means samples and specimens are placed under vacuum system in the course of analysis.
Electron microscopes provide you with very high magnification and resolution power. It allows the greater depth field of study and material is rarely distorted by preparation. On the other hand, its size, cost, the expense of maintenance makes it difficult to use in small labs.
Transmission electron microscope (TEM)
The transmission electron microscope is used to see the interior of cells, protein structure, molecular arrangement and organization in living cells, cytoskeletal fragments, viruses, etc.
In this type of electron microscope, electrons pass through the specimen to generate the image. So, for this, the specimen should be ultra-thin.
Scanning electron microscope (SEM)
A scanning electron microscope produces an image by scanning the specimen with the help of a focused electron beam. These are used to generate images of objects which cannot be seen by TEM.
MCQs
- What is microscopy?
- A) Studying large objects
- B) Viewing and observing small objects with a microscope
- C) Examining visible objects
- D) Magnifying human eye vision
- Answer: B
- What is the purpose of using microscopes in biological studies?
- A) To study large organisms
- B) To observe natural colors of specimens
- C) To magnify objects up to 1500X
- D) To view and understand small and transparent objects
- Answer: D
- What is the primary function of a microscope?
- A) Decreasing the size of objects
- B) Reducing resolution power
- C) Increasing the size of objects for better visibility
- D) Magnifying and resolving small objects
- Answer: D
- What are simple microscopes?
- A) Microscopes with two lenses
- B) Microscopes with only one lens
- C) Microscopes using electron beams
- D) Microscopes with advanced features
- Answer: B
- Which type of microscope uses visible light for illumination?
- A) Electron microscope
- B) Compound microscope
- C) Scanning electron microscope
- D) Light microscope
- Answer: D
- What is the limitation of light microscopes in terms of magnification?
- A) Up to 500X
- B) Up to 1000X
- C) Up to 1500X
- D) Up to 2000X
- Answer: C
- Which of the following is NOT a part of a light microscope?
- A) Objective lens
- B) Condenser lens
- C) Electromagnetic fields
- D) Table
- Answer: C
- What is the purpose of electron microscopy?
- A) To observe natural colors of specimens
- B) To study large organisms
- C) To get high-resolution images of small objects
- D) To magnify objects up to 500X
- Answer: C
- How does an electron microscope achieve high resolution?
- A) Uses a vacuum system
- B) Employs visible light waves
- C) Utilizes a shorter wavelength of electrons
- D) Operates at low voltages
- Answer: C
- Which microscope type is used to see the interior of cells and protein structures?
- A) Scanning electron microscope (SEM)
- B) Compound microscope
- C) Transmission electron microscope (TEM)
- D) Light microscope
- Answer: C
- What is the primary principle of working for electron microscopes?
- A) Uses visible light waves
- B) Employs electromagnetic fields
- C) Accelerates an electron beam
- D) Operates at low voltages
- Answer: C
- Why is the specimen for a transmission electron microscope required to be ultra-thin?
- A) To increase resolution
- B) To decrease magnification
- C) To avoid vacuum system
- D) To enhance natural colors
- Answer: A
- Which microscope type scans the specimen with a focused electron beam?
- A) Transmission electron microscope (TEM)
- B) Light microscope
- C) Scanning electron microscope (SEM)
- D) Compound microscope
- Answer: C
- What is a disadvantage of electron microscopes?
- A) Low magnification
- B) Low resolution
- C) Distortion of material during preparation
- D) Inexpensive maintenance
- Answer: C
- What does SEM stand for in microscopy?
- A) Simple Electron Microscope
- B) Single Energy Microscope
- C) Scanning Electron Microscope
- D) Specific Electron Magnifier
- Answer: C
- What does TEM stand for in microscopy?
- A) Traditional Electron Microscope
- B) Transparent Electron Magnifier
- C) Transmission Electron Microscope
- D) Total Energy Microscope
- Answer: C
- Which microscope type is used to generate images of objects that cannot be seen by TEM?
- A) Scanning electron microscope (SEM)
- B) Compound microscope
- C) Transmission electron microscope (TEM)
- D) Light microscope
- Answer: A
- What is the primary function of light microscopes in biological studies?
- A) High magnification
- B) Viewing natural colors of specimens
- C) Easy to purchase and simple to use
- D) Observation of large organisms
- Answer: C
- What is the wavelength range typically used in electron microscopy for high resolution?
- A) 1 to 5 Aᵒ
- B) 10 to 20 Aᵒ
- C) 5 to 12 Aᵒ
- D) 15 to 25 Aᵒ
- Answer: C
- Which part of the light microscope is responsible for magnifying the image of the object?
- A) Base
- B) Objective lens
- C) Table
- D) Fine focus
- Answer: B
Summary
In conclusion, the tutorial on Microscopes and Microscopy delves into the technical utilization of microscopes to observe objects and specimens invisible to the naked eye, enabling the study of cellular structures, compositions, and the molecular nature of cells. The tutorial covers various types of microscopes, emphasizing light microscopes and electron microscopy.
A microscope, as a crucial instrument, offers high magnification and resolving power, surpassing human eye capabilities. The tutorial introduces two primary microscope types: simple microscopes with one lens and compound microscopes with eyepieces and lenses.
Light Microscope:
- Utilizes visible light for illumination.
- Affordable, easy to use, but limited to magnification up to 1500X.
- Components include eyepiece, objective lens, condenser lens, stage, fine focus, base, and table.
Electron Microscopy:
- A technique for high-resolution imaging of biological and non-biological specimens.
- Operates with a shorter wavelength, achieving resolutions as low as 3 Aᵒ.
- Uses an electron beam accelerated by high voltages (20,000 to 100,000 volts).
- Divided into Transmission Electron Microscope (TEM) for interior details and Scanning Electron Microscope (SEM) for surface scanning.
Principle of Working for Electron Microscopes:
- Involves accelerating an electron beam from a heated metal wire.
- Utilizes electromagnetic fields and optical lenses for magnification.
- Operates under vacuum conditions for specimen analysis.
While electron microscopes offer exceptional magnification and resolution, their size, cost, and maintenance expenses pose challenges for small labs. The Transmission Electron Microscope (TEM) is employed for detailed interior examinations, requiring ultra-thin specimens, while the Scanning Electron Microscope (SEM) scans surfaces using a focused electron beam.
This tutorial provides insights into the diverse world of microscopy, empowering scientists to explore the intricate details of cells, tissues, and micro-entities.