Chapter 3: Observing Microorganisms Through A Microscope Flashcards
Total magnification
Objective lens x ocular
Parfocal
Little refocusing; having lenses w/ focal points that are all in the same plane
Resolution
Resolving power; ability of lenses to distinguish fine detail of specimen
Distinguish between 2 points that are a specified distance apart
Refractive index
Light-bending ability
Immersion oil is used to keep light bending away- improves resolving power; if not used poor resolution, fuzzy
Changes refractive index by staining them
Ocular lens (eyepiece)
Remagnifies and the image formed by the objective lens
Body tube
Transmits the image from the objective lens to the ocular lens
Stage
Hold the microscope slide in position
Condenser
Focuses light through specimen
Lens located below microscope that directs light rays through the specimen
Diaphragm
Controls the amount of light entering the condenser
Coarse
Focusing knob; 10x
Fine focusing knob
40x and 100x
Brightfield (light) microscopy
Light reflected off the specimen does not enter the objective lens
Which part of compound light microscope magnifies the specimen?
Ocular lens
Which part of compound light microscope magnifies the specimen?
Ocular lens
Signs and symptoms of active pulmonary TB (lower respiratory infection)
Signs- weight loss?, coughing up blood?, abnormal breathing
Symptoms- chest pain, no appetite, fatigue, night sweats, chills, fever
Discuss the cell wall acid fast bacilli
Contains waxy material- mycolic acid (creates a barrier-making this bacteria resistant to certain antibacterial agents as well as common staining methods, like gram stain, acid-fast staining overcomes this barrier-allowing for observation of acid-fast bacilli)
Acid fast bacilli’s most active member
Mycobacterium TB (causative of TB)
Steps of acid fasting staining
- Air dry and heat fix a thin film of microorganisms. Allow the slide to cool.
- Flood the slide with Carbolfuchsin. Steam the slide with a Bunsen burner over the sink. Let the slide set for 5 minutes. Rinse with water.
- Flood slide with Acid Alcohol for 30 seconds. Rinse with water.
- Counterstain by flooding the slide with Methylene Blue for 30 seconds. Rinse with water.
- Dry the slide by putting it between the pages of a book of Bibulous paper.
- View organisms using the oil immersion objective of your microscope.
Gram stain
Examined differences in bacterial cell wall, classifying bacteria into 2 groups:
1)gram-+. (Stain purple)
2)gram- - (does not retain stain purple➡️ clear➡️ stain pink)
Type of differential stain
Acid fast stain
Identifies a specific group of bacteria- acid fast bacilli
Used to identify Mycobacterium species. Once stained with carbolfuschin and treated w/ acid-alcohol, remain pink or red b/c they retain carbolfuschin stain. Non-acid fast bacteria when stained and treated the same way and then stained w/ methylene blue, appear blue
Sputum
Phlegm
Clinical application of acid fast stain
To identify presence of bacteria like Myobacterium TB
Microscopy units
1) micrometer= 0.000001m (1x10^-6)
2)nm= 0.00000000m (1x10^-9)
Compound light microscopy (LM)
Series of lenses and use visible light as its source of illumination
Best for stained bacterial smear and examining a clinical specimen like sputum smear
Max magnification: 1500x
Max resolution: 0.2micrometers