microscopy

Question 1

Parts of the Light Microscope

Answer 1

Optical Parts:
* Eyepiece (ocular lens): Magnifies the image.
* Objective lens: Further magnifies and resolves the image.
* Condenser: Focuses light on the specimen.

Mechanical Parts:
* Base, arm, stage: Support and hold the specimen.
* Coarse and fine adjustment knobs: Focus the image.
* Light source: Provides illumination.

Question 2

Magnification

Answer 2

Magnification = Eyepiece magnification × Objective lens magnification.

Example:
Eyepiece = X6, Objective lens = X10:
Totalmagnification
=
6×10 = 60.
Totalmagnification=6×10=60.

Question 3

Light Microscope

Answer 3

• Uses light to form images by passing through or reflecting off specimens.
• Specimens must be transparent for light to pass through.
• Allows observation of both living and non-living specimens.

Question 4

Microscope Overview

Answer 4

A microscope is a device that magnifies objects too small to be seen by the naked eye. It allows visualization at scales ranging from millimeters to nanometers.

Question 5

Size Range

Answer 5

Light microscopes: View objects as small as 0.2 micrometers (e.g., bacteria) to larger objects like 1 millimeter.
Electron microscopes: Can resolve structures as tiny as 1 angstrom (10^-10 m), such as atoms.

Question 6

Cell Size Calculations

Answer 6

Conversion factors:
1 meter = 1000 millimeters (mm).
1 mm = 1000 micrometers (µm).
1 µm = 1000 nanometers (nm).
Example: Calculate how many cells of 100 µm diameter can fit side-by-side in 1 mm:
Cellsthatfit

Question 7

Image Focusing

Answer 7

Resolution: The ability to distinguish between two close objects.

• Use coarse adjustment knobs for low/medium power and fine adjustment knobs for high power

Question 8

Focusing Steps

Answer 8

1. Place the slide on the stage with the region of interest centered.
2. Always start focusing at low power.
3. Use coarse knobs first, then fine knobs for sharpness.

Question 9

Microscopic Slides

Answer 9

Permanent slides: Prepared and preserved for long-term use.
Temporary slides: Quickly prepared for immediate use, such as wet mounts.
* Wet mount procedure: Place water on the slide, add the specimen, and carefully lower the coverslip to avoid air bubbles.**

Question 10

Biological Drawings

Answer 10

Guidelines for drawings:
1. Use a pencil.
2. Make large, clear, detailed drawings with proper annotations.
3. Indicate magnification and use scale bars to represent actual sizes.

Question 11

Determining Cell Size

Answer 11

• Field of View (FOV):The visible area through the microscope.
  Example: FOV = 450 µm.
  Estimate how many cells fit across the FOV.
  If 5 cells fit, cell size =

Cellsize= FOV/Numberofcells =
450µm/5
​
=90µm.

Question 12

Electron Microscopy

Answer 12

• Transmission Electron Microscope (TEM): Produces detailed 2D images of internal structures.
• Scanning Electron Microscope (SEM): Produces detailed 3D images of surfaces.
  —> Comparison to light microscopes:
  Higher magnification and resolution.
  Can only view dead specimens due to preparation techniques

Question 13

Drawing and Annotating

Answer 13

When drawing organelles or cells:
* Use double lines for membranes (e.g., nuclear, mitochondrial).
* Avoid overlapping or multiple lines.
* Include scale bars and calculate magnification
* include title