Microscopes and cells lab report

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The Microscope

 Zacharias Janssen is to be credited for inventing the first truly compound microscope

Microscope

What is a microscope?

  • It is a tool or instrument often used in laboratories to aid in viewing organisms that cannot be seen with an unaided eye

Types of microscope

Biologist often used different microscope

Compound light microscope

Dissection microscope

Scanning electron microscope(SEM)

Transmission electron microscope(TEM)

but of all, the compound light microscope is what we shall be using

Dissecting Vs. Compound light microscope

Scanning Vs. Transmission electron Microscope

Microscope

  • Compound light microscope is simply a microscope that has at least two magnifying lenses (the oculars and the objectives)
  • Binocular microscope possess two eyepieces (what we shall be using in the lab)
  • Monocular microscope possess one eyepieces

Bi = two mono = one

Microscopes

  • Electron microscope magnifies the specimen 1000X larger than the light microscope
  • The Dissecting microscope on the other hand has a low magnification power (7X to 30X). It is used to view large objects

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Microscope

  • There are a variety of light microscope but each differs by the emission of light through the specimen that is viewed

Phase contrast

Darkfield

Polarizing

UV

Terms

  • Bright Field:  illumination, sample contrast comes from absorbance of light in the sample.

  • Cross polarized light: illumination, sample contrast comes from rotation of polarized light through the sample.

Terms

  • Dark Field: illumination, sample contrast comes from light scattered  by the sample.
  • Working distance: distance between the specimen and the objective lens ( is this distance greater with the 40x or the 10x objective ? Ans: 10x )

Phase Contrast: illumination, sample contrast comes from interference of different path lengths of light through the sample.

labels

  • Light source, a light or a mirror (7)
  • Diaphragm and condenser lens (8)
  • Objective (3)
  • Ocular lens (eyepiece) (1)
  • In addition the vast majority of microscopes have the same 'structural' components:
  • Objective turret/ nosepiece (to hold multiple objective lenses) (2)

Labels

  • Stage (to hold the sample) (6)
  • Focus wheel to move the stage (4 - coarse adjustment, 5 - fine adjustment)
  •  Stage adjustment knobs (9)

Terms used when dealing with a microscope

The head

  • It supports the two sets of magnifying lenses

The Oculars (eyes)

  • It is the lenses used to view the specimen.
  • Located on the eyepiece
  • Has a magnification of 10X

Microscope

Interpupillary distance

  • This is the distance between the eyepiece on a binocular microscope
  • It can be adjusted to suit your eyes

Field of view “FOV”

  • the diameter of the circle of light that you see when looking into a microscope

Microscope (cont..)

Objectives

  • These are the four lenses on the revolving nosepiece
  • Four types exist: 4x , 10x , 40x , 100x

4X : the scanning lens

10X: the intermediate lens

40X: the high power lens

100X: the oil immersion lens

Microscope(cont..)

The Arm

  • The part of the microscope that connects the tube to the base

The Condenser lens

  • it focuses the light onto the specimen.
  • It can be located in or below the stage

Microscope (cont..)

The Adjustment Knob

  • used to adjust the height of the condenser

Iris Diaphram

  • It controls the amount of light that passes to reach a specimen

Stage

  • The flat plate where the slides are placed for observation.

Microscope (cont..)

Stage Clips

  • Clips on the stage used to hold the slide in place

Stage Adjustment Knob

  • Found on mechanical stage
  • Aids in moving the stage left to right or back and forth (vice versa)

Microscope(cont…)

Fine Focus

  • This is the knob used to fine tune the focus on the specimen.
  •   It is also used to focus on various parts of the specimen. 
  • Generally one uses the coarse focus first to get close then moves to the fine focus knob for fine tuning.

Microscope(cont..)

Coarse Focus

  • This is the rough focus knob on the microscope. 
  • You use it to move the objective lenses toward or away from the specimen

Base

  • The bottom support of the microscope

How to Use a Microscope

To carry a microscope, place one hand on the arm and the other on the base of your microscope

Clean the Microscope

  • It is imperative to clean the lenses of your microscope each time you use begin an experiment
  • Clean using lens paper moistened with distilled water, then again without the water

How to Use a Microscope(cont..)

2. Plug in your microscope and turn on the light.

3. Begin viewing from 4X. If the lens is not at 4X rotate till you get it

4. Make sure you always clean a prepared slide before viewing it. Place it on the stage

5. While looking through your oculars,(if binocular move the lenses until to are able to view just an image of the specimen) feel free to adjust your specimen using your coarse adjustment

How to Use a Microscope(cont..)

6. The correct position of your condenser is when you slowly lower the condenser until the graininess disappear. While that of the iris diaphram is when you slowly open the diaphram until the entire field of view is illuminated

7. Rotate the nosepiece using different objective lenses

How to Use a Microscope(cont..)

NB: do not view your specimen using the 100X objective without using immersion oil.

8. At the end of your exercise, turn off your microscope and clean before returning it in the cabinet.

ONE HAND ON THE ARM & ONE HAND ON THE BASE!!!!!!

Calculations

What would be the total magnification if the ocular were 10X and the objective 40X?

  • 10 x 40 = 400X

Organization of Cells

Prokaryotes: These are singled (one) celled organisms. Eg: bacteria. They have a diameter of approximately 1 micrometer (μm).

  • They lack a nucleus (houses the genetic materials). Genetic material is stored in the nucleiod region (cytoplasm)
  • They have a cell membrane, flagellum (pl. – flagella) aids in mobility.
  • Asexual reproduction

Organization of Cells (cont..)

Eukaryotes: These are cells with a nucleus and membrane bound organelles

Eg: plasma membrane, mitochondria, golgi apparatus, chloroplast, ER, cilia and flagella, etc.

Unicellular: singled celled (can survive by itself)

Aggregates: clusters of cells

Colonies: A consistent and predictable # of cells

Organization of Cells(cont…)

Multicellular: Large # of cells, each cells has a special function.

NB: none can exist successfully without the other.

Lab Exercise

  • Learn how to use the light compound microscope.
  • Identify parts of light compound microscope
  • Unicellular organism: Examine the prepared slide of Amoeba it moves using Pseudopodia(False feet )
  • Aggregate and Colonial Organism: Examine the prepared slide Volvox

Lab Exercise

  • Multicellular Organisms:
  • CellTissue OrganOrgan system
  • Examine some of the cells that compose the basic tissue types of plants and animals.
  • Plant cells: cell wall, protoplasm,cytoplasm, central vacuole, chloroplasts, nucleus
  • Animal cells: Human epithelial cells ( cheek cells)

Lab Exercise

  • To obtain a specimen ( epithelial cell or cheek cells):
  • 1. With a clean toothpick, gently scrape the inside of your cheek several times
  • 2. Roll the scraping into a drop of water on a clean microscope slide, add a small drop of methylene blue, and cover with a coverslip . Discard the used toothpick in disinfectant
  • 3. Using the compound microscope, view the cells under high power, identify the cell membrane, nucleus, and cytoplasm.