2.1 Microscopy

Question 1

What does cell theory state

Answer 1

Plant and animal tissues are composed of cells

Question 2

What are the two lenses in a LM called and what are they used for

Answer 2

Objective lens-placed near the specimen and produces a magnified image

Eyepiece Lens- allows for much higher magnification

Question 3

Describe how you would make a dry mount specimen

Answer 3

A cover slip is placed on the specimen thats it

Question 4

How would you prepare a wet mount

Answer 4

Specimens are suspended in water or immersion oil

A cover slip is placed at an angle

Used for aquatic organisms

Question 5

How would you prepare a squash slide

Answer 5

Create a wet mount first then a lens tissue is used to gently press down on the cover slip

Question 6

How would you create a smear slide

Answer 6

Use the edge of a slide to smear the sample

then use a cover slip over the sample

Good for seeing individual blood cells

Question 7

Describe the Gram stain technique

Answer 7

Crystal violet is applied to a bacterial specimen, then iodine which fixes the dye.
Then was the slide with alcohol.

Gram positive will retain the stain, appearing blue/purple

Gram negative have thinner cell walls so will lose the stain

AFTER they will be stained with safranin dye (counter stain) causing the negative bacteria to appear red

Question 8

What antibiotic is Gram positive bacteria more suce[table to

Answer 8

penicillin because it inhibits cell wall formation

Question 9

Why are Gram negative bacteria less susceptible to penicillin

Answer 9

They have much thinner cell walls

Question 10

What is acid-fast staining used for

Answer 10

Differentiating species of mycobacterium from other bacteria

Question 11

Outline the technique of acid-fast staining

Answer 11

A lipid solvent is used to carry carbolfuchsin dye into cells

Then the cells are washed with dilute alc.

Mycobacterium arent affected by the acid alcohol and retain corbolfuchsin stain causing them to appear bright red

Other bacteria are then exposed to methylene blue stain

Question 12

What are the 4 stages involved in producing a microscope slide

Answer 12

Fixing
Sectioning
Staining
Mounting

Question 13

Describe how you would prepare a slide

Answer 13

1Fix the slide- use chemicals such as formaldehyde to preserve them

2 Section- dehydrate the slide with alcohols then place in a wax/ mould

3-stain- stain to show different structures

4-mount-secure it on a microscope slide and place a cover slip on it

Question 14

measurements

Answer 14

1mm=1000um
1um=1000nm

Question 15

TEM vs LM
SEM

Answer 15

x500k mag x2000

Question 16

resolving power

Answer 16

ability to differentiate between two lines

Question 17

Laser scanning confocal microscopy

Answer 17

Moves a single spot of light(spot illumination) across the specimen
-causes fluorescence from the compononents labelled with dye
-filtered through a pinhole aperature

Question 18

artefact

Answer 18

look like part of the sample but are side effects of sample preparation