Types of Microscopes Quiz

Types of Microscopes

• Microscopes are tools used to view tiny biological objects invisible to the naked eye.
• Different types of microscopes are available, each with unique features and applications.
• Light microscopes use light to illuminate and magnify specimens.
  • Compound light microscopes use multiple lenses to magnify specimens.
  • Binocular Dissecting microscopes (stereomicroscopes) provide a three-dimensional view of specimens.
  • Phase contrast microscopes enhance contrast between different parts of a specimen.
• Fluorescent microscopes use fluorescent dyes to illuminate and visualize specific structures within a specimen.
  • Confocal microscopes are a type of fluorescent microscope that uses lasers to scan and create images of very thin slices of a specimen.
• Electron microscopes use electrons to illuminate and magnify specimens.
  • Transmission electron microscopes (TEMs) create images of the internal structures of a specimen.
  • Scanning electron microscopes (SEMs) create images of the surface of a specimen.

Compound Light Microscope

• Compound light microscopes are the most common type used in biological research and education.
• They use two sets of lenses: objective lens and eyepiece lens.
• Light from a lamp is focused on the specimen by a condenser lens.
• The specimen is placed on a glass slide with a coverslip on top.
• The objective lens magnifies the specimen, and the eyepiece lens further magnifies the image.
• The total magnification is calculated by multiplying the magnification of the objective lens by the magnification of the eyepiece lens.
• Resolution is the ability to distinguish between two points that are close together.
• Compound light microscopes typically have a resolution of about 0.2 micrometers.

Learning Outcomes

• Define molecular biology methods and techniques.
• Explain DNA cloning techniques.
• Describe DNA and plasmid extraction.
• Describe the CRISPR-Cas9 system.
• Describe DNA synthesis and DNA microarray.
• Explain the different types of DNA mutation.

Molecular Biology Methods

• Used to study the molecular basis of biological activity.
• Goal to isolate and analyze cellular components, exploring cells, their characteristics, and processes.
• Commonly used methods include:
  • Nucleic acid methods
  • Protein methods
  • Immunostaining methods

Standard Practices in the Laboratory

• Gloves: Protect from contamination and chemicals, don't touch common surfaces outside of lab, use ungloved hand for common surfaces when leaving lab.
• Mouth: Don't put anything in mouth (food, drinks, chewing gum), don't pipette by mouth, avoid dangerous substance intake.
• Makeup: Don't apply makeup or adjust contact lenses.
• Benchtop: Keep clean, have only necessary lab materials, leave active experiments unattended.
• Disinfect: Benchtop before and after experiments to prevent contamination.
• Clean hands: Keep hands clean before and after lab experiments.
• Safety: Don't run in the lab, don't sit on laboratory benches.
• Unauthorized Experiments: Strictly forbidden, never work without supervision.
• Long Hair/Loose Clothing: Tie back long hair and secure loose clothing when working with open flames.
• Eye Protection: Goggles, safety glasses or face shields required when working with UV light and any procedure that could cause splashes.
• Footwear: Closed toed shoes required to protect from chemical spills and sharp objects.
• Safety Equipment: Know the location of safety equipment like eyewash, chemical shower, first aid kit, and fire extinguisher.

Laboratory Safety Equipment

• Chemical hygiene plans ensure lab worker safety from chemical hazards.
• Fume hoods or biosafety cabinets should be used as directed.

Lab Emergencies

• Notify instructor immediately for any spills, accidents, or injuries (chemical/biological spills, personal injuries, broken glass, equipment).

Biohazard Bin

• Properly labeled bins or bags for biohazardous waste (non-reusable items contaminated with infectious agents, body fluids, animal tissue).

Fluorescent Proteins and Stains

• Red Fluorescent Protein (RFP)
• Green Fluorescent Protein (GFP)
• DAPI (4′,6-diamidino-2-phenylindole): Fluorescent stain that binds to adenine-thymine rich regions in DNA.

Confocal Microscopes

• Laser Scanning Confocal Microscopes (LSCM):
  • Optical sections are produced by scanning the specimen point by point with a focused laser beam.
  • Pinhole removes fluorescence from above and below the focal plane.
  • Imaging structures at discrete levels within an intact biological specimen.

Electron Microscope

• Uses a beam of electrons magnified and focused by electron magnetics.
• Views smaller objects compared to light microscopes with greater detail.
• Transmission Electron Microscope (TEM): Analogous to compound light microscope.
• Scanning Electron Microscope (SEM): Analogous to dissecting light microscope.
• Specimen preparation is extensive, potentially introducing artifacts.

Microscope Use

• Keep both eyes open when using the microscope.
• Never touch the eyepiece with your eyelashes.
• Lowest power objective should be in position at the beginning and end of use.
• Don't clean lenses with regular paper tissue.
• Don't tilt the microscope when viewing.
• Don't remove parts of the microscope.
• Locate small objects first with the naked eye or under low power.
• Always begin focusing with the scanning power objective (4x).

Focusing the Microscope

• Lower stage with coarse adjustment knob. Place slide on stage and secure with clip.
• While looking through eyepiece, slowly raise the stage until the object comes into view.
• Fine adjustment knob sharpens focus if needed.

Laboratory Safety

• Laboratories present various hazards, including corrosive chemicals, sharp objects, and open flames.
• Microorganisms are categorized into four biosafety levels (BSL) based on their transmissibility and pathogenicity.
• BSL-1 organisms, commonly used in undergraduate labs, are generally not harmful to healthy individuals.
• BSL-4 organisms, requiring specialized labs, include highly dangerous pathogens like Marburg and hantaviruses.
• Lab coats are crucial for protecting against contamination.
• Always wear gloves to safeguard hands from chemicals and microorganisms, but avoid touching surfaces outside the lab with them.
• Never consume food, drink, or chew gum in the lab.
• Avoid applying makeup or adjusting contact lenses within the laboratory.
• Always keep the lab bench clean and organized, removing personal belongings (e.g., cell phones, bags).
• Never leave experiments unattended, especially those involving heat or reactions.
• Disinfect the lab bench before and after each experiment.
• Maintain hand hygiene before, after, and whenever contacting potential hazards.
• Never run in the laboratory.
• Do not sit on lab benches.
• Unauthorized experiments are strictly prohibited.
• Always work under supervision.
• Tie back long hair and secure loose clothing, especially when working with open flames.
• Wear goggles or face shields when using UV light or during procedures that generate aerosols or splashes.
• Wear closed-toe shoes to protect against chemical spills and sharp objects.
• Familiarize yourself with the location of safety equipment (eyewash station, chemical shower, first aid kit, fire extinguisher).
• Utilize fume hoods or biosafety cabinets as instructed.
• Report any spills, accidents, or injuries immediately to the instructor.
• Dispose of biohazardous waste (non-reusable items, animal tissue) in properly labeled bins or bags.
• Use sharps containers for broken glass, needles, scalpel blades, and other sharp objects.
• Place non-contaminated waste paper or trash in regular trash cans.
• Sterilize reusable materials in an autoclave before discarding, while non-sterile materials can be washed in the sink.
• Always keep chemical containers tightly closed to prevent vapor escape.
• Never use unmarked or unidentified reagents; consult your instructor if uncertain.
• Use appropriate carrying methods for chemicals, avoiding contact with your body.
• Always face chemical bottle labels upward when pouring to prevent damage.
• Never add chemicals to bottles other than their intended contents.
• Dilute acids by slowly pouring acid into water, stirring continuously.
• Properly dispose of chemicals according to institutional guidelines.
• Wash hands thoroughly before and after each experiment.
• Removing jewelry is important for proper handwashing.
• Apply soap and lather for at least 20 seconds, rubbing hands together thoroughly.
• Rinse hands thoroughly under running water.
• Dry hands with a clean towel or air dryer.
• The SI (International System of Units) is the standard system of measurement used by scientists.
• The SI system prefixes are based on the number 10, simplifying calculations.
• All measurements require a number and a unit.